受賞区分：国内学会・会議・シンポジウム等の賞  受賞国：日本国

受賞区分：学会誌・学術雑誌による顕彰  受賞国：日本国

受賞区分：国内学会・会議・シンポジウム等の賞  受賞国：日本国

受賞区分：学会誌・学術雑誌による顕彰  受賞国：日本国

受賞国：日本国

受賞区分：国内学会・会議・シンポジウム等の賞  受賞国：日本国

受賞区分：国内学会・会議・シンポジウム等の賞  受賞国：日本国

受賞国：日本国

受賞国：日本国

受賞国：日本国

受賞国：日本国

記述言語：日本語   出版者・発行元：Transportation Research Procedia  

Impact of heavy vehicles on roundabout entry capacity is generally considered through a heavy vehicle adjustment factor fHV which is calculated by heavy vehicle percentage and passenger car equivalent (PCE hereafter) value. The PCE value of trucks is generally set as 2.0 and estimated based on several considerations such as entry capacity and move-up time. All of these considerations are influenced by local driver behavior and geometry conditions. Thus, this paper aims to estimate entry capacity considering the characteristics of heavy vehicle behavior in Japan by microscopic simulation. Then based on the simulation results, the PCE value is also examined. Through the simulation study it is found that entry capacity is reduced when heavy vehicle percentage increases. Moreover, estimated PCE results show that the PCE value of entry flow increases when circulating flow increases but decreases when circulating flow is in high level. Also it is found that PCE of entry flow is lower than that of circulating flow which has priority at roundabouts.

DOI： 10.1016/j.trpro.2016.06.026

Web of Science

Scopus

記述言語：日本語   出版者・発行元：Transportation Research Procedia  

This study aims to find out the necessary target travel speeds of roads in functionally hierarchical network which can achieve the target travel times for connecting centers with five different functions, considering the distribution of centers in the subjective area. In this paper, hierarchical road classification scenarios which consists of target travel speeds and road spacings are developed for differentiating road functions. Then travel times under the certain scenario are numerically calculated by an approximate method. Here, the calculation is based on a combination of hypothetical grid network and the actual motorway network. Finally, an application study of Tokaido region in Japan and southwest region in Germany demonstrated the impact of hierarchical road classification scenario on the achievement of the target travel time between centers in different categories.

DOI： 10.1016/j.trpro.2016.06.061

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Scopus

記述言語：日本語  

DOI： 10.1016/j.sbspro.2014.07.225

Web of Science

記述言語：日本語  

DOI： 10.1016/j.sbspro.2014.07.233

Web of Science

記述言語：日本語  

DOI： 10.1016/j.sbspro.2012.04.090

Web of Science

出版者・発行元：Transport Policy  

In Japan, the mobility functions of principal arterial roads are hindered by lined-up roadside facilities and densely located signalized intersections. As one of the solutions, it is necessary to consider a functional hierarchy of road networks, based on the structure and traffic operations of each road. The purpose of this study was to propose an index to evaluate the degree to which the road network could be used hierarchically according to their mobility function, based on the location of the bases and the location of roads at each level of the hierarchy, and to propose a method to evaluate the road network using this index. To accomplish this, we proposed a four-level method for the evaluation of the functional hierarchy of road networks based on the derived index values. As a case study, we calculated the degree of hierarchy for the road networks in northern Mie and western Shizuoka. The results showed that the current evaluations of the functional hierarchy in these regions were low, and that introducing mid-level roads was necessary to improve the current situation. The evaluation method proposed in this study will enable us to examine the ideal network configuration for each road in the region to exhibit its mobility function as a preliminary step to studying solutions to various road network issues, such as ensuring the smooth movement between bases and safety. © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the World Conference on Transport Research – WCTR 2023.

DOI： 10.1016/j.tranpol.2024.06.012

Scopus

出版者・発行元：IATSS Research  

Until early 2000s, modern roundabouts (RABs) were poorly understood in Japan and were not fully recognized as a form of at-grade intersections. The RAB research projects of the International Association of Traffic and Safety Sciences (IATSS), which began in 2009, started with examining the applicability of RABs in Japan and have steadily progressed to various stages of field experiments, social implementation, and dissemination promotion activities. These RAB research projects, which lasted for approximately seven years, are considered to have played a significant role in the practical application of RAB in Japan. This paper provides a chronological overview of the history, content, and development status of these projects and records and discusses the role that IATSS research projects played in the early days of RABs in Japan.

DOI： 10.1016/j.iatssr.2024.02.006

Scopus

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p><tt>近年、日本の道路ネットワークは概成しつつあるものの、道路の旅行速度は諸外国に対して低い水準にあると言われている。このため、交通量の影響が小さい状態での旅行速度を国内外で比較し、旅行速度差の要因となっている道路構造、交通運用を明らかにすることは重要である。昨今では</tt>Google Maps<tt>による位置情報や航空写真の収集と公開により、世界各国の旅行速度や道路構造を簡便に把握できるようになりつつある。そこで本稿では、</tt>Google Maps<tt>を用いて、日本、アメリカ、ドイツの閑散時旅行速度を比較し、それらの差の要因を分析することを目的とする。分析の結果、日本の閑散時旅行速度はアメリカやドイツに対して低く、その要因として、信号交差点密度の差や規制速度の設定基準の違いが挙げられることを定量的に明らかにした。</tt></p>

DOI： 10.14954/jste.10.2_1

CiNii Research

出版者・発行元：Sustainability (Switzerland)  

Crossing pedestrians may significantly affect the capacity of the left-turn (LT) lane at signalized intersections while sharing the same signal phase in the left-hand traffic system, the quantitative estimation method is still not intensively discussed when considering the vehicle yielding maneuver. Despite the Road Traffic Act in Japan mandating vehicles to yield to pedestrians, instances of vehicles crossing in front of pedestrians are frequent. This study aims to refine the evaluation of LT lane capacity by introducing a novel vehicle yielding maneuver model, considering factors such as pedestrian numbers, crosswalk length, and signal timing. The model, developed using data from various Japanese crosswalks, is subjected to Monte Carlo simulation for validation. Comparative analysis with existing methods in Japanese and U.S. manuals, along with observed data, highlights the effectiveness of our model. This innovative approach has the potential to mitigate vehicle–pedestrian conflicts and reduce air pollution. By incorporating techniques such as signal optimization and two-stage crossing, our model contributes to sustainability while maintaining efficient traffic flow.

DOI： 10.3390/su16062313

Scopus

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p>道路ネットワークが概成したわが国において、依然として発生している道路交通問題の解決策の一つとして、機能階層型道路ネットワークの考え方が重要である。本研究では、道路ネットワークがどの程度機能階層的に利用されるかを評価する方法について提案する。3つの階層を設定した仮想道路ネットワークにおいて、自由走行時を対象とした最短経路探索を行い、トリップ長と階層利用に基づく道路利用特性指標を算出する。この指標値から想定される道路ネットワークの利用状態を基に、その機能階層性を4段階で評価する方法を提案した。そして、岐阜南部と静岡西部の道路ネットワークを対象としてケーススタディを行った。その結果、現状では機能階層性に関する評価は低く、これを向上するためには、中位階層の道路整備が必要であることが明らかとなった。</p>

DOI： 10.14954/jste.9.2_a_69

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p>これまでの堅実な整備により日本の道路ネットワークは概成しつつあるが、道路ネットワークを構成する各道路の交通機能の性能の考慮が必ずしも十分でなく、幹線道路での低い旅行速度や生活道路での抜け道利用といった問題が残されている。このため、各道路が目指すべき交通機能に応じて階層的に利用されているかといった機能階層性の観点から、道路ネットワークを見直す必要がある。そこで本研究は、道路計画設計の専門家に対するアンケート調査によって、機能階層性に影響を与える要因を明らかにすることを目的とする。調査の結果、機能階層性にはトリップ長、旅行速度に関する条件が相互に影響することを確認し、それらの組合せによって機能階層性を評価する必要性を明らかにした。</p>

DOI： 10.14954/jste.9.2_a_35

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

近年、日本の道路ネットワークは概成しつつあるものの、道路の旅行速度は諸外国に対して低い水準にあると言われている。このため、交通量の影響が小さい状態での旅行速度を国内外で比較し、旅行速度差の要因となっている道路構造、交通運用を明らかにすることは重要である。昨今ではGoogle Mapsによる位置情報や航空写真の収集と公開により、世界各国の旅行速度や道路構造を簡便に把握できるようになりつつある。そこで本稿では、Google Mapsを用いて、日本、アメリカ、ドイツの閑散時旅行速度を比較し、それらの差の要因を分析することを目的とする。分析の結果、日本の閑散時旅行速度はアメリカやドイツに対して低く、その要因として、信号交差点密度の差や規制速度の設定基準の違いが挙げられることを定量的に明らかにした。

DOI： 10.14954/jsteproceeding.43.0_403

CiNii Research

出版者・発行元：Physica A: Statistical Mechanics and its Applications  

The emergence of Autonomous Vehicles (AVs) could provoke unexpected challenges in urban traffic environments. One such crucial challenge is the conflicts between pedestrians and AVs, particularly on unsignalized mid-block crosswalks (UMC), where pedestrians are exposed to the AV flow. This study investigates the efficiency and safety performance of a UMC in the presence of both AVs and pedestrians considering the diversities in their behaviors. Through empirical analyses, two pedestrians’ crossing decision models are built and four groups of speed profiles are classified. Meanwhile, based on previous literature, defensive and competitive driving strategies are assumed for AVs. The simulation is implemented on an agent-based framework that can dynamically reproduce the kinematic interactions between pedestrians and vehicles. Results indicated that with a reasonable safety margin (2.5 s), percentages of low post encroachment time events for competitive AVs with different pedestrian types are smaller than defensive AVs with differences of 0.2% to 2.9%. The average delays of competitive AVs for all pedestrian types are smaller than defensive AVs with a maximum estimated difference of 39 s. Moreover, the analysis showed that lowering the speed limit may reduce the crash rate of competitive AV up to 0%. It is also found that the pedestrians who make reckless crossing decisions and change their speed drastically during the crossing process are more likely to incur crashes with competitive AVs. Therefore, if pedestrian behaviors can be regulated reasonably, competitive AVs with appropriate parameter settings are most suitable for UMC in the future.

DOI： 10.1016/j.physa.2022.128083

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Scopus

記述言語：英語   出版者・発行元：Accident Analysis and Prevention  

Pedestrian distraction may provoke severe difficulties in automated vehicle (AV) control, which may significantly affect the safety performance of AVs, especially at unsignalized mid-block crosswalks (UMCs). However, there is no available motion-planning model for AVs that considers the effect of pedestrian distraction on UMCs. This study aims to explore innovative approaches for safe and reasonable automated driving in response to distracted pedestrians with various speed profiles at UMCs. Based on two common model design concepts, two new models are established for AVs: a rule-based model that solves motion plans through a fixed calculation procedure incorporating several optimization models, and a learning-based model that replaces the deterministic optimization process with policy-gradient reinforcement learning. The developed models were assessed through simulation experiments in which pedestrian speed profiles were defined using empirical data from field surveys. The results reveal that the learning-based model has outstanding safety performance, whereas the rule-based model leads to remarkable safety problems. For distracted pedestrians with significant crossing-speed changes, rule-based AVs lead to a 5.1% probability of serious conflict and a 1.4% crash probability. The learning-based model is oversensitive to risk and always induces high braking rates, which results in unnecessary efficiency loss. To overcome this, a hybrid model based on the learning-based model was developed, which introduces a rule-based acceleration value to regularize the action space of the proposed learning-based model. The results indicate that the hybrid approach outperforms the other two models in preventing crash hazards from distracted pedestrians by employing appropriate braking behaviors. The high safety performance of the hybrid models can be attributed to the spontaneous slowing down of the vehicle that initiates before detecting pedestrians on UMCs. Although such a cautious driving pattern leads to extra delay, the time cost of the hybrid model is acceptable considering the significant improvements in ensuring pedestrian safety.

DOI： 10.1016/j.aap.2022.106711

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Scopus

PubMed

出版者・発行元：Transportation Research Part F: Traffic Psychology and Behaviour  

Traffic safety has always been a hot topic for human-driven (HDV) and autonomous vehicles (AV) mixed flow. The conflict between permitted right-turn vehicles (PRT) and opposing through vehicles (TH) at signalized intersections (left-handed traffic) is extraordinarily critical. AVs with aggressive behaviors are able to accept short gap time without losing safety. However, such a turning maneuver may lead to dangerous feelings and cause unexpected reactions of approaching drivers. This study aims to investigate and model drivers’ reactions in TH movements to PRT AVs considering the trust degree of drivers to AVs. Questionnaire surveys and driving simulator experiments were conducted for 41 participants. Results reveal that the right turn timing of PRT AV will significantly influence drivers’ reactions. Basically, TH drivers will brake with a high probability under the situation of small expected post encroachment time (PET). It is also found that female drivers and drivers with low trust in AVs are more vigilant to PRT AVs than other drivers. Based on this finding a two-layer model for reproducing TH drivers’ reactions to PRT AVs is proposed. The first layer is to determine the braking decision and the second layer is to calculate the parameters of braking behaviors (brake lag, braking time, and speed drop). The significance and coefficients variables in these models proved that the trust in AV will influence drivers’ decisions and braking behaviors (brake lag and braking time). The more the drivers trust AVs, the smaller the expected PET to AVs they can accept for passing without braking, and the more gently they will brake (longer brake lag and shorter braking time) due to the cutting in of PRT AVs. This effect will become significant after drivers have experienced several interactions with AVs.

DOI： 10.1016/j.trf.2022.06.018

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Scopus

出版者・発行元：Transportation Research Part C: Emerging Technologies  

Merging sections on freeways are typical bottlenecks for traffic efficiency and safety. The connected and automated vehicles (CAV) technology has great capability in improving traffic performance of merging bottlenecks. Current approaches of system optimal cooperative merging control assume single fixed merging point (CMC-SMP) for on-ramp vehicles to reduce the complexity of their models. Non-fixed merging positions have the potential to further improve merging operations but may lead to the computational explosion. To solve this core contradiction, this study proposes a novel hierarchical system optimal cooperative merging control model considering flexible merging positions (CMC-FMP) to realize safe and efficient merging processes. The upper-level – the tactical planning model is formulated as a non-convex mixed integer quadratically constrained programming, aiming at minimal total travel time in the control zone. It optimizes not only the merging sequence but also vehicles’ critical states in merging processes, such as the state of on-ramp vehicles when they merge. The lower-level - the motion planning model generates feasible trajectories and the next step actions for every vehicle. A Monte Carlo Tree Search-based decomposition algorithm (MCTS-DA) is further designed to improve the computational efficiency of the tactical planning model. Meanwhile, solutions of MCTS-DA are proved to have good optimality compared to the direct solving method. A batch-based scheme is developed to realize real-time control. The results reveal that the average delays of CMC-FMP are remarkably lower than those of CMC-SMP. Especially in low on-ramp ratio scenarios, the difference in improvement can reach 64%. Furthermore, the sensitivity analysis indicates that large safe merging margins and short merging sections are disadvantageous for traffic efficiency for the merging flow controlled by CMC-FMP.

DOI： 10.1016/j.trc.2022.103650

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Scopus

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p>愛知県豊橋市牧野町における県道と市道の 4 枝無信号交差点は，総流入交通量が約 15,000 台/日と比較的多いが無信号で運用されている．そして，市道が鋭角の食い違い交差となっていることなど，交通安全上の課題を抱えている．その対策案として，瓢箪型ラウンドアバウトの導入が計画されているものの，国内では市街地における導入事例がなく，また，ラウンドアバウトマニュアルにおいても正円でないラウンドアバウトの幾何構造に関する設計の考え方などは記載がない状況である．そこで本研究では，実験フィールドに実物大の仮設ラウンドアバウトを設置し，実証実験を通して瓢箪型ラウンドアバウトの形状を検討した．本稿では，各種実験の概要と分析結果，および望ましいラウンドアバウト形状の検討結果について報告する．</p>

DOI： 10.14954/jste.8.4_b_18

CiNii Research

記述言語：日本語   出版者・発行元：International Journal of Intelligent Transportation Systems Research  

Field experiments of autonomous vehicles (AVs) have been conducted in many countries. However, efficiency evaluation of AV mixed flow and safety evaluation of conflicts between AVs and pedestrians in the real-world case are still limited. This study aims at evaluating the efficiency and safety of left-turn (LT) vehicles and pedestrians in signalized intersections, under the condition of AV mixed flow, by developing a simulation model. Post Encroachment Time (PET) and LT capacity were obtained. Further, gap/lag acceptance behavior and reaction time of LT vehicles were found to be critical parameters that affect efficiency and safety evaluations.

DOI： 10.1007/s13177-021-00276-z

Web of Science

Scopus

出版者・発行元：IATSS Research  

Road traffic crashes (RTCs) are influenced by a driver's awareness and attitude toward road safety, as well as the socio-economic status, infrastructure development level, traffic status, social system, and traffic safety culture of the area to which the driver belongs. In this study, based on the results of a questionnaire survey conducted in seven countries, the characteristics of each country concerning tolerance for traffic violations, dangerous driving, and acceptance for road safety measures were studied. It was suggested that a high tolerance for traffic violations and dangerous driving might affect traffic violations and RTCs in each country. Additionally, to reduce the tolerance for traffic violations and dangerous driving, the promotion of road safety education, especially among young and male drivers, and stricter regulations and enforcement were suggested.

DOI： 10.1016/j.iatssr.2021.10.002

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Scopus

出版者・発行元：IATSS Research  

Road traffic safety is a crucial global objective. It is important for every country to review and improve road safety policies and strategies, based on an objective understanding of its own road traffic safety situation in the world. With the aim of contributing to such a review and understanding, this study conducted a multi-country survey to gather information about various facts related to legislation, enforcement, and education, which are designed to achieve safer drivers in nine countries, by using a common format. This paper introduces the results of the survey with a particular focus on legislation and enforcement regarding speed limit violations and red-light-running as well as on education within the driving licensing systems. It highlights variations, in terms of penalty settings and enforcement levels, in different countries; it also examines the training durations necessary for acquiring a driving license and license renewal procedures. In this way, it demonstrates the potential and significance of understanding the relative position of each country in terms of road traffic safety through an international comparison despite its limited information.

DOI： 10.1016/j.iatssr.2022.01.004

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Scopus

出版者・発行元：IATSS Research  

DOI： 10.1016/j.iatssr.2022.03.005

Web of Science

Scopus

出版者・発行元：IATSS Research  

Traffic violations are recognized as one of the main causes of traffic accidents and have been found to be closely associated with driver attitudes toward traffic safety. In this study, a modified theory of planned behavior (TPB) was used to model the effects of driver safety attitudes on traffic violations, based on a questionnaire survey of 1505 drivers in China. In light of the strong correlations between the observed items, the items of the TPB components were grouped into several parcels, using an item-parceling method. Parcel-based structural equation modeling was then used to operationalize the modified TPB. The results indicate that the proposed model can accurately predict the occurrence of traffic violations based on the observed items related to driver traffic safety attitudes. It was found that driver attitudes, subjective norm, and perceived behavior control significantly affect traffic violations. For predicting traffic violations, driver attitudes toward traffic safety policies had the greatest influence, followed by driver attitudes toward risky driving behaviors and the attitudes of others toward risky driving behaviors. Finally, suggestions on traffic enforcement and education to reduce traffic violations are proposed based on the results.

DOI： 10.1016/j.iatssr.2022.02.001

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Scopus

出版者・発行元：IATSS Research  

One of the main pillars for improving road safety in any country is a good understanding of traffic safety culture and the driving behavior of local drivers. The primary aim of this study was to determine whether Egyptian drivers differ in traffic safety attitudes and level of acceptance of risky driving behavior. A questionnaire survey was conducted on the driving cognition of the participants. An exploratory factor analysis was used to assess the number of factors that differentiated the three types of drivers. Then a hierarchical cluster analysis was performed to group the drivers with similar patterns of scores on the factors into clusters. Three driver clusters emerged: The drivers in cluster 1 were “drivers who rigidly followed regulations” (51.7%). The drivers in cluster 2 were “drivers who violated safety precautions” (23.3%). The drivers in cluster 3 were “drivers who had a tendency to violate regulations” (25.0%). A similarity between the social norms and personal attitudes of drivers was found. This can be explained by the high social norm of violating traffic laws, which can lead to more drivers accepting violations. The majority of the older drivers and drivers with no violations or traffic accident on their record in the past 2 years were in cluster 1. Cluster 2 had the highest proportion of young drivers who wore their seat belts and used hands-free phones while driving. Cluster 3 drivers accepted very dangerous violations, such as texting while driving, driving while intoxicated, and driving at very high speeds. They reported significantly more traffic accidents, but no more violations than the other two clusters. The results of this study can be used to improve road safety programs for education and enforcement in Egypt.

DOI： 10.1016/j.iatssr.2021.11.007

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Scopus

出版者・発行元：IATSS Research  

While the number of road fatalities is declining in developed countries, it is still increasing globally, especially in middle-and low-income countries. In addition to the driver's individual awareness and attitude toward traffic safety, various factors such as the development of road infrastructure and the legal system may have a significant influence on the occurrence of traffic accidents. Thus, it is essential to consider these factors to enhance traffic safety and achieve Sustainable Development Goal (SDG) Targets of 3.6. In this study, we developed an Elastic Net Regression model to evaluate the factors that influence an individual's traffic violations and accidents based on an international questionnaire on traffic safety attitude, country fact survey data on traffic regulations, and other statistical databases. As a result, it was revealed that: i) In addition to country-level factors, the individual's attributes and attitudes toward traffic safety have an influence on the experience of traffic violations and accidents. and ii) While the same variables regarding individual attributes and attitudes are selected for both traffic violations and accidents, the selected variables relating to country factors differ between violations and accidents.

DOI： 10.1016/j.iatssr.2021.12.004

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Scopus

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

<p>Full signalized traffic circles are operating in some countries to serve the heavy turning traffic flows at large-sized road junctions. Their capacities are influenced by many factors, such as the traffic conditions, signal control types and geometric layouts. The objective of this study is to find out the specified traffic demand conditions that signalized traffic circles are preferred in different cases of the number of lanes and lane configurations. A signal optimization model for the traffic circles is proposed for investigating five cases of signalized traffic circles under various traffic demand conditions. The results showed that signalized traffic circles have higher capacity than signalized intersections in some specific cases, e.g. when the total number of approach lanes reaches five or when more than one right-turn lanes are required. Besides, an analysis on the relationship between the capacity and the occupied area is conducted to further consider the geometric influence.</p>

DOI： 10.11175/easts.14.1958

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

<p>Weaving segments can be one of the crucial road facilities in terms of efficiency and safety on urban expressways. The traffic operation in weaving segment is different from the basic segment due to the crossing of multiple traffic streams. Also, quality of service (QOS) varies among lanes due to different lane utilization rate (LUR). Therefore, this study aims at establishing a lane-based evaluation procedure of QOS through developing LUR estimation models. With the data from two urban expressway sections in Nagoya and Tokyo, Japan, LUR is found to be significantly affected by cross-section flow, merging ratios, diverging ratios, and cross-section position. The model validation reveals that the model can reproduce traffic distribution. Lane-based average speed and density are adopted as measure of effectiveness (MOE), and level of service (LOS) criteria is determined by cluster analysis. Case study shows that the procedure can reflect QOS in each lane at every cross-section.</p>

DOI： 10.11175/easts.14.1870

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p>道路事業評価は、種級区分や車線数などに応じて一律に決まる日単位の交通量-速度関係(Q-V)を用いて費用便益分析を行っている。しかし、既往の Q-V では実際の道路交通条件を十分正確に反映できないことや、地域の交通量の変動を十分に考慮できてないことなど、その設定方法に根本的な課題が残されている。本研究では、道路構造・交通運用を考慮した時間交通量-速度関係(q-v)と交通量変動指標を用いて、Q-V のモデル化を行った。実観測データの交通量変動と q-v から各時間帯の時間平均旅行速度を算出し、重み付き調和平均をとることにより、ある日交通量時の日平均旅行速度を算出し、Q-V を設定した。この Q-V は、ピーク率と昼夜率の値によってその形状を説明でき、構築したモデルにより実際の道路・交通条件を考慮した Q-V の推定が可能となった。</p>

DOI： 10.14954/jste.8.2_a_62

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p>日本各地において、様々な幾何構造のラウンドアバウト(RAB)が導入されており、今後さらに普及が進んでいくと考えられる。しかし、設計時の想定と実際の走行位置が異なることで、中央島などの構造物への接触や、小型車であるにも関わらずエプロン上を走行するといった事例が散見される。車両の走行位置には、RAB の中央島直径や隅角部形状といった様々な幾何構造要素の組み合わせが大きく影響するが、その関連性は未だ十分明らかとなっていない。そこで本研究では、日本の RAB を対象に、幾何構造要素の違いが走行位置に与える影響を明らかにすることを目的とする。分析結果から、エプロン幅員や環道幅員が走行位置に大きな影響を与えることが確認された。また、走行位置分布の推定モデルを用いることで、設計段階において走行位置を予測することが可能となった。</p>

DOI： 10.14954/jste.8.2_a_15

CiNii Research

出版者・発行元：Asian Transport Studies  

Conflicts between pedestrians and left-turning vehicles cause pedestrian safety hazards and decrease vehicle turning capacity at signalized intersections. This commonly occurs in Japan where they share the same traffic light phase. Road capacity is influenced by the interaction between them. Autonomous vehicles (AVs) promise to improve the safety and efficiency of road networks. However, they will face the same problems as human-driven vehicles with pedestrian avoidance. Thus, this study estimated the capacity of the left-turn lane, in Japan, under AV mixed flows taking into account AV penetration rates, pedestrian flow rates, and crosswalk length. The impact of AVs on capacity was analyzed with different settings for the critical gap between vehicles and pedestrians. It was found that if AVs comply perfectly with traffic law, the capacity of the left-turn lane sharply decreases, especially in the case of long crosswalks.

DOI： 10.1016/j.eastsj.2022.100070

Scopus

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p>道路ネットワークが概成したわが国において、依然として発生している道路交通問題の解決策の一つとして、機能階層型道路ネットワークの考え方が重要である。本研究では、道路ネットワークがどの程度機能階層的に利用しうるかを評価する方法について提案する。3つの階層を設定した仮想道路ネットワークにおいて、自由走行時を対象とした最短経路探索を行い、トリップ長と階層利用に関する道路利用特性指標を算出する。この指標値から想定される道路ネットワークの状態から、その機能階層性を4段階の階層化度で評価する方法を提案した。そして、岐阜南部と静岡西部の道路ネットワークを対象としてケーススタディを行った。その結果、現状では機能階層性に関する評価は低く、これを向上するためには、中位階層の道路が必要であることが明らかとなった。</p>

DOI： 10.14954/jsteproceeding.42.0_455

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p>これまでの堅実な整備により日本の道路ネットワークは概成しつつあるが、道路ネットワークを構成する各道路の交通機能の性能の考慮が必ずしも十分でなく、幹線道路での低い旅行速度や生活道路での抜け道利用といった問題が残存している。このため、各道路が目指すべき交通機能に応じて階層的に利用されているかといった機能階層性の観点から、道路ネットワークを見直す必要がある。そこで本研究は、道路計画設計の専門家に対するアンケート調査によって、機能階層性に影響を与える要因を明らかにすることを目的とする。調査の結果、機能階層性にはトリップ長、旅行速度に関する条件が相互に影響することを確認し、それらの組合せによって機能階層性を評価する必要性を明らかにした。</p>

DOI： 10.14954/jsteproceeding.42.0_463

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

<p>近年，日本の年間交通事故死者数は減少傾向にある．今後，交通事故を一層減らすためには，交通事故につながる交通違反・危険運転などの不安全行動とそれに対するドライバーの認識との関係を正しく理解し，効果的な取締り・交通安全政策を実施していく必要がある．そこで本研究では，各種不安全行動に対するドライバーの認識の関連を定量的に示すことを目的とする．日本のドライバーに対するアンケート調査データを用いて構造方程式モデリングを行った結果，ドライバー認識が行動の決定に与える影響の大きさは，年齢層が若いほど不安全行動を肯定する態度と運転技能への自信の影響が大きく，容認による影響は小さいことがわかった．この年齢層による影響の差は，飲酒運転と漫然運転で顕著に見られ，速度超過運転ではその差は小さいことがわかった．</p>

DOI： 10.2208/jscejipm.77.5_i_915

CiNii Research

記述言語：英語   出版者・発行元：Accident Analysis and Prevention  

Visibility can be identified as one of the critical determinants for the safety performance of autonomous vehicles (AVs) on unsignalized mid-block crosswalks (UMC), which may be significantly influenced by build-up environment and surrounding vehicles. This study investigates the safety performance when AVs interact with pedestrians approaching from far-side sidewalks to UMCs considering the visual occlusion of opposing vehicles. A mathematical model is proposed for judging the visibilities of objects from observers’ location under the impact of visual obstacles and is embedded into an agent-based pedestrian-vehicle interaction framework. Two yielding decision modules is assumed for AVs: The normal decision module implements the pedestrian priority rule simply based on the current detectable information, whereas the memory aid decision module extends AVs’ detection abilities by incorporating the memory data. Through simulation experiments, it is found that the percentages of short post encroachment time (%SPET) between AVs and far-side pedestrians reach peaks when the pedestrian flow rate is 300–400 ped/h. When opposing vehicles are in stationary queue conditions, %SPETs are only sensitive to the net distance between the last opposing vehicles in the queue and crosswalks (Dqueue). As the Dqueue decreases to lower than 15 m, %SPETs start to increase drastically. However, when opposing vehicles are in free flow conditions, %SPETs are influenced by multiple factors such as pedestrians’ crossing decisions, sizes and flow rates of opposing vehicles. Furthermore, only when opposing vehicles are in free flow conditions, memory aid AVs can significantly eliminate the impacts of opposite vehicles. Finally, several countermeasures are developed to enhance the visibility and safety at UMCs based on the findings of this study.

DOI： 10.1016/j.aap.2021.106468

Web of Science

Scopus

PubMed

記述言語：英語   出版者・発行元：Accident Analysis and Prevention  

A critical safety problem in road networks is the conflicts on unsignalized crosswalks. Thus, a proactive approach to assess pedestrian safety performance is required. Simulating the microscopic road user behavior in a virtual platform is one of the typical approaches. However, current simulation tools are not flexible enough to properly reproduce various behaviors of pedestrians and drivers considering their interactions with the road environment and other road users. Therefore, the objective of this paper is to propose a novel agent-based framework for evaluating pedestrian safety at unsignalized crosswalks. Unsignalized mid-block crosswalks with refuge islands (UMCR) are considered as an example facility to implement the proposed framework, where relevant behavioral elements such as the reaction time, visual field with obstacles, and minimum safety margin time are addressed. Not only the pedestrian-vehicle interaction is modeled but also the vehicle-vehicle interaction is considered. Empirical validation on a UMCR shows that the proposed framework can reproduce reliable distributions of the post encroachment time compared to the observed distributions within an acceptable error range. The sensitivity analysis reveals that the high reaction time of drivers, small safety margin time, and visual obstacles near crosswalks increase the probability of serious conflicts. The results also show that the framework can reproduce traffic crashes under assumed extreme road conditions.

DOI： 10.1016/j.aap.2021.106288

Web of Science

Scopus

PubMed

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

記述言語：英語  

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.12962/j20861206.v36i1.9100

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 交通工学研究会  

<p>愛知県の主要渋滞箇所の一つである春日井インター東交差点は、右折交通量に対して右折車線長が不足しており、右折待ち行列が直進車線まで延伸する状況が発生していた。その結果、後続直進車の通行が阻害され渋滞の要因の一つになっているとともに、右折待ち行列の末尾等への追突事故の危険性が懸念されていた。そこで本研究では、当該交差点において、右折待ち行列の延伸による渋滞解消のため、サイクル長を短縮する実証実験を実施した。本稿は、この実験に伴う円滑性・安全性の改善効果を検証した結果について報告するものである。</p>

DOI： 10.14954/jste.7.2_b_55

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p>愛知県は交通事故死者数が令和元年に 17 年ぶりに全国ワーストを脱却したが、今後更なる安全な道路交通環境の実現に向け、関係機関の一層の努力が求められている。本研究では、信号のサイクル長が長いことに起因して渋滞が発生し、これに伴う生活エリアへの通過交通により危険性が高まっている箇所を対象にサイクル長の短縮について検討し、実証実験により安全性や円滑性の観点から効果検証を行った。結果、右折レーンのない交差点など直進阻害が生じ信号の青時間が有効活用されていない箇所においてはサイクル長の短縮により、渋滞緩和や事故の危険性低下が確認された。一方、生活エリアへの抜け道利用の抑制効果については十分な効果がみられず、利用者への効果周知や生活道路への物理的デバイスの同時整備の必要性など今後の課題として確認した。</p>

DOI： 10.14954/jste.7.2_b_6

CiNii Research

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1080/23249935.2021.1895360

記述言語：英語   出版者・発行元：Asian Transport Studies  

Turbo roundabouts have been a popular choice of road intersections in the European countries in recent years, since they have better operational and safety performance than conventional roundabouts. To serve the heavy traffic demands, signal controls can be implemented on turbo roundabouts. The objective of this study is to clarify the specific traffic conditions, under which signalized turbo roundabouts are selected to install compared with signalized intersections. The twice-stop-right-turn control method is used for turbo roundabouts under the left-hand driving system. A signal control optimization model for turbo roundabouts is developed. Sensitivity analysis is made to capture the influence of entry volume and the right-turn movement ratio on capacity and average delay. Furthermore, the trend of the capacity of roundabouts with the radius of the central island is studied. It is found that under heavy balanced entry volumes, signalized turbo roundabouts have better operational performance than signalized intersections.

DOI： 10.1016/j.eastsj.2021.100033

Scopus

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

記述言語：英語   出版者・発行元：公益社団法人 土木学会  

<p>Crossing pedestrians is one of the critical factors in proper estimation of turning vehicle capacities at signalized intersections. Although individual pedestrian walking speeds and consequent pedestrian platoon maneuver are influenced by traffic signal settings, crosswalk length and bidirectional interactions of pedestrian flows, the existing capacity estimation methods of left-turning vehicles did not consider these impacts. This study aims to propose a method to estimate the expected pedestrian presence-time that pedestrian platoon occupies the conflict-area, considering the characteristics of pedestrian platoon maneuvers. Referring to the existing method to estimate time-dependent pedestrian presence probability distributions, this study re-estimated the parameters of the model using the additional database with higher pedestrian demand conditions. The model revealed that the increase of opposing pedestrian flow significantly reduces spatial variation. This model was applied to calculate expected pedestri</p>

DOI： 10.2208/jscejipm.76.5_i_1485

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

<p>我が国の道路ネットワークは概成しつつあるが，本来発揮すべきサービスを十分提供できていない道路も多い．これらの解決には，道路ネットワークの機能的階層化によって各道路が発揮すべきサービス目標を明確にし，実道路の性能との乖離を明らかにすることが必要であると考えらえる．そこで本研究では，実道路の性能照査を行うことを目指し，任意の道路ネットワークの性能目標設定手法を提案することを目的とする．仮想の起点・終点間に，それぞれラインホール，および一般道路を用いる2つの経路を仮定し，ラインホールを用いる経路が最短時間または最小コストとなる道路ネットワークの必要条件を求めた．この必要条件を性能目標として，実道路を対象としたケーススタディにより性能目標を明らかにし，これらと実道路の性能の実態との乖離を明示した．</p>

DOI： 10.2208/jscejipm.76.5_i_1235

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

<p>わが国の幹線道路では，信号交差点等の影響により旅行速度が依然として低く，本来求められる交通機能が十分に発揮されていない．この問題を解決するため，道路構造や交通運用の差別化を図りトリップの利用特性に応じた道路の役割分担を促す，道路の機能階層化が重要である．本研究では，3階層の道路ネ ットワークにおける道路・交通運用条件が，各階層の利用特性に与える影響を把握する．そして，道路ネ ットワークの機能階層的な利用を表現する指標を設定し，これを用いて道路ネットワークが機能階層的に利用されるための必要条件を検討した．その結果，IC間隔が短いほど階層間の自由速度の差別化が必要となる等，国内で課題となっている中位階層の幹線道路が明示的に利用されるための道路・交通運用条件の範囲を示すことが可能となった．</p>

DOI： 10.2208/jscejipm.76.5_i_1453

CiNii Research

掲載種別：研究論文（学術雑誌）   出版者・発行元：IATSS Research  

DOI： 10.1016/j.iatssr.2020.10.001

Web of Science

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Accident Analysis and Prevention  

In the geometric design of roundabouts, safety-oriented approaches are required rather than specification design ones that simply determine the dimensions of the geometric structural elements. We herein propose a risk index (RI) that combines the invisibility probability and the crash impact as a performance measure for evaluating the safety of the geometric designs of roundabouts, and we also describe a method for calculating this index. Invisibility probability represents the probability that an entering vehicle cannot view a vehicle coming from the upstream in a circulatory roadway and crash impact represents the amount of lost kinetic energy at the time of collision corresponds to the impact of the crash. A numerical simulation to model this RI on the basis of various geometric conditions is further presented. It is demonstrated that the invisibility probability is large when the entry angle is small and that the crash impact increases when the deviation angle decreases. The proposed approach is expected to help resolve issues with currently existing roundabouts and improve the design of future roundabouts to enhance their safety performance.

DOI： 10.1016/j.aap.2020.105702

Web of Science

Scopus

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s13369-020-04810-1

記述言語：日本語   出版者・発行元：公益財団法人 国際交通安全学会  

<p>近年、日本の年間交通事故件数および事故死者数は減少しているものの、その減少量は小さくなっている。今後、より効果的に交通事故を削減するために、交通安全対策は、自動車運転者の交通安全意識を踏まえて実施する必要がある。本研究では、IATSS研究調査プロジェクトの一環として、国や地域ごとに異なる交通安全意識を理解するため、日本、イタリア、エジプトの自動車運転者に対してアンケート調査を行った。本データのサンプルには偏りがあることは否めないながらも、交通違反・危険運転に対する許容度を比較分析することにより、各国の運転者の交通安全に対する意識の特徴を把握した。</p>

DOI： 10.24572/iatssreview.45.1_58

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Safety Research  

Introduction: Heterogeneous driving populations with many different origins are likely to have various sub-cultures that comprise of drivers with shared driver characteristics, most likely with dissimilar traffic safety cultures. An innovative methodology in traffic safety research is introduced which is beneficial for large datasets with multiple variables, making it useful for the multi-variate classification of drivers, driving attitudes and/or (risky) driving behaviours. Method: With the application of multidimensional scaling analysis (MDS), this study explores traffic safety culture in the State of Qatar using a questionnaire and investigates the similarity patterns between the questionnaire items, aiming to classify attitudes towards risky driving behaviours into themes. MDS is subsequently applied to classify drivers within a heterogeneous driving sample into sub-cultures with shared driver characteristics and different risky driving attitudes. Results: Results show that acceptance of speeding is highest among the young Arabic students and acceptance of distraction and drivers’ negligence such as phone use and not wearing a seatbelt is highest among male Arab drivers. Acceptance of extreme risk-taking like intoxicated driving and red-light running is highest among South-Asian business drivers. Conclusion: It is important and practical to understand risky behavioural habits among sub-cultures and thereby focussing on groups of drivers instead of individuals, because groups are easier to approach and drivers within sub-cultures are found to influence each other. By indicating which groups of drivers are most likely to perform specific risky driving themes, it is possible to target these groups and effectively emphasise certain subsets of risky driving behaviours during training or traffic safety education. Practical Applications: This study provides guidance for the improvement of driver education and targeted traffic safety awareness campaigns, intending to make changes to attitudes and habits within specific driver sub-cultures with the aim to improve traffic safety on the longer term.

DOI： 10.1016/j.jsr.2020.02.009

Web of Science

Scopus

PubMed

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Transportation Research Record  

This study estimated composite headway distributions consisting of follower and non-follower headway elements and used the follower percentage obtained as the estimated parameters of those distributions to evaluate the quality of service (QOS) of traffic flow on Japanese intercity expressways under uncongested conditions. Analysis of pulse data obtained by vehicle detectors at multiple points with differing geometric structures showed that follower percentage is influenced by lane traffic volume, vehicle pair, and lane operation. Use of follower percentage also enabled clear and quantitative comparison and evaluation of the QOS of traffic flow for different lane operation formats, which could not be adequately expressed by such conventional macroscopic indices as average speed and traffic density. This indicates that follower percentage is a suitable performance measure for evaluating the QOS of traffic flow.

DOI： 10.1177/0361198120918575

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Arabian Journal for Science and Engineering  

In areas where traffic demand is high and intersections are closely spaced, the drivers’ desire for quick discharge is demotivated by negative downstream conditions, such as long queues and poorly coordinated traffic signals, which may lead to lower saturation flow rate (SFR) for upstream lane groups. However, existing models do not consider this phenomenon. This paper proposes an improved intelligent driver model for reproducing the impacts of downstream traffic conditions on the discharging behavior of vehicles and the estimated SFR. A micro-simulation platform for two closely spaced signalized intersections is built to test the improved car-following model and to simulate the influenced SFR. Results from the sensitivity analysis and the comparison with empirical data show that the developed model could rationally and reliably reproduce the SFR reduction under different downstream conditions. As the queue in the downstream segment becomes longer and the offset becomes larger due to poor coordination, the SFR at the upstream intersection deteriorates. The developed model can be applied in traffic simulations to provide more realistic discharging behavior considering the downstream conditions.

DOI： 10.1007/s13369-020-04411-y

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Transportation Research Record  

Arterials are important transportation facilities, undertaking the two functions of mobility and accessibility. In the urban area, signalized intersections along arterials are usually closely spaced and bear heavy traffic pressure. Capacities of intersections can be reduced by downstream intersections even without having spillback. This effect will be accumulated and amplified back along the traffic direction and may lead to severe congestion in the upstream intersection which can be frequently observed, especially during peak hours. However, existing traffic simulators cannot capture this phenomenon accurately because they ignore the capacity drop before spillback happens. In this study, downstream influence is quantified by a virtual optimal speed (vop). vop is the speed by which the upstream platoon reaches the endpoint of the queue ahead when the last vehicle in the downstream queue just starts. Based on that, two piecewise regression models, for start-up lost time and saturation flow rate, are formulated to estimate the capacity reduction. These regression models are further introduced to improve the modified cell transmission model (CTM). The result of the simulation experiment shows that the proposed CTM model has better performance in simulating traffic flow on signalized arterials than the existing CTM, especially in reproducing the traffic congestion in upstream. The analysis emphasized the importance of considering the downstream influence when simulating the traffic on signalized arterials. Finally, a sensitivity analysis is designed to further reveal the causes of upstream congestion.

DOI： 10.1177/0361198120916477

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 交通工学研究会  

<p><tt>本研究では，交通流のサービスの質として，追従状態の程度などの機動性が利用者認識に関わる要素を明示していると捉え，それを表現し得る評価指標について検討した．追従状態の程度を表す評価指標には，追従車と非追従車の車頭時間成分からなる合成車頭時間分布曲線を推定することで得られるパラメータのひとつである，追従車構成率を採用した．幾何構造の異なる都市間高速道路上に設置された複数地点の車両感知器により検出されたパルスデータを用いて分析を行ったところ，追従車構成率は，車線，車線交通量，車種構成，車線運用によって影響を受けることが明らかとなった．また，小型車と大型車の挙動特性を反映し，追従車を実際の交通現象に即して確率的に捕捉することができ，非渋滞時における高速道路の交通流のサービスの質の評価に相応しい指標であることを示した．</tt></p>

DOI： 10.14954/jste.6.2_a_9

CiNii Research

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 交通工学研究会  

<p><tt>道路事業を進めるにあたっては、費用便益分析により事業実施の妥当性を評価している。その際、道路種別に応じた交通量</tt>-<tt>旅行速度（</tt>Q-V<tt>）式を用いて交通量配分を行っているが、平面交差部の立体化等の道路事業では交通量に変化がなければ推定される旅行速度に感度がなく、事業の効果を適切に反映できていない。本論文では、交通流シミュレータを用いて信号交差点密度が </tt>Q-V <tt>式の自由速度に与える影響を分析し、平面交差部の立体化に感度を有する </tt>Q-V <tt>関係による便益算出への影響を評価した。その結果、</tt>Q-V <tt>式の自由速度は、信号交差点密度、青時間比、希望速度に応じて変化することを確認した。そして、</tt>1OD 2 <tt>経路の簡易ネットワークを用いて、信号交差密度を考慮した自由速度を用いる </tt>Q-V <tt>関係で道路事業の三便益を算出し、従来手法との便益差により新しい </tt>Q-V <tt>関係の効果を明らかにした</tt><tt>。 </tt></p>

DOI： 10.14954/jste.6.2_a_198

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人 交通工学研究会  

<p>Free speed (FS) is the speed that drivers would adopt if they were not influenced by the presence of other vehicles. This study hypothesises that the difference between the free speed distribution (FSD) and the actual speed distribution (ASD) is indicative of the quality of service (QOS) of traffic flow perceived by drivers. We use raw pulse detector data and the Modified Kaplan-Meier estimation method to derive FSD, which is then modelled based on cross-section geometry. The proposed model of FSD can be easily applied by practitioners without detailed speed and headway data. Additionally, ASD is investigated under various flow conditions, and a model is developed for its estimation based on geometric factors and traffic flow. We then define the Free Speed Index, <i>FSI = AS/FS</i> as an indicator of expressway QOS perception. <i>FSI</i> was found to decrease with an increase in traffic flow, and its potential applications are discussed.</p>

DOI： 10.14954/jste.6.2_a_244

CiNii Research

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Transportation Research Procedia  

Signalized intersections are the major causes of delay to vehicular traffic along signalized arterials. Although a lot of research has been conducted about the optimization of the performance of signalized intersections, it is mostly applicable to the operations stage and involves changing signal phasing schemes. However, due to cost of roadways construction and the additional improvements after construction, the assessment of the potential performance of the roadway is very important even at the planning stage so that the plans do not call for some unfavorable design features along the arterial. The lack of performance oriented planning often leads to poor performance, such as very low travel speeds. In this work, we investigate the travel speed along a hypothesized 4-lane signalized arterial, and examine how it changes due to the signalized intersection density, cycle length, mean desired speed, and the function of the intersection. Results showed that cycle lengths up to 120 seconds were sufficient to yield high travel speed. At higher intersection densities, lower travel speeds will be achieved regardless of the mean desired speed. The function of the signalized intersection was also significant, showing the possibility of maintaining the traffic function of an arterial if it were crossed by a lower level road in the hierarchy. The importance of performance evaluation at the planning stage was further emphasized.

DOI： 10.1016/j.trpro.2020.08.106

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IATSS Research  

Professional drivers play a significant role within the traffic system of the State of Qatar. With developing infrastructure, the need for professional drivers is growing. However, knowledge is lacking about their perception of traffic safety. Therefore, this study investigates the personal acceptance of risky driving and suggested traffic laws among this specific group of drivers, in order to create understanding about their likelihood to commit certain risky driving behaviors and their resistance to the implementation of certain traffic laws. The aim of this study is to establish which personal attributes of professional drivers in Qatar could influence a high likelihood to commit risky driving behaviors, estimating which specific groups of professional drivers impose the highest risk to violate certain traffic laws. Results indicate that transportation mode, origin and years of driving experience are all personal attributes that have a significant impact on the professional driver's risk to commit risky driving behaviors and their opposition to the implementation of related traffic laws. Distressing results have been found for the high likelihood to violate speed in school zones and the high risk to be distracted by any type of phone use while driving, suggesting the need to put emphasize on these safety hazards during the training programs of professional drivers at professional driving schools in the State of Qatar.

DOI： 10.1016/j.iatssr.2019.03.004

Web of Science

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語  

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p><tt>近年、運転支援システムが実用化され始め、自動運転システムによる安全性や円滑性の向上に期待が高まってきている。しかしながら、自動運転車の普及段階においては、必ずしもこれらの期待が実現するとは限らない。特に、信号交差点においては、車両が複雑に干渉しあうため、自動運転車の挙動パラメータの設定次第で円滑性に影響が出ることが懸念される。そこで本論文では、自動運転車の挙動パラメータ設定が信号交差点の直進車線の交通容量に与える影響をシミュレーションとモデル式を用いて分析し、自動運転車のパラメータと混入率を考慮した交通容量を算定した。その結果、自動運転車が普及することで信号のサイクル長を短くできることが明らかになった一方で、自動運転車のパラメータを慎重な設定にすることにより、円滑性が低下する可能性が示唆され</tt><tt>た。</tt></p>

DOI： 10.14954/jste.5.2_a_167

CiNii Research

掲載種別：研究論文（学術雑誌）   出版者・発行元：Global Practices on Road Traffic Signal Control: Fixed-Time Control at Isolated Intersections  

DOI： 10.1016/B978-0-12-815302-4.00001-7

Scopus

記述言語：英語   出版者・発行元：公益社団法人 土木学会  

<p>Entry capacity is one of the most important indexes to evaluate the roundabout operational performance. Both the geometric elements and vehicle types have an impact on the entry capacity. Passenger Car Equivalent (PCE) for heavy vehicles is utilized for roundabout entry capacity estimation. In the Japanese Roundabout Manual (JRM), PCE is proposed as a constant value. However, it cannot reflect that the capacity of roundabouts varies with different geometric elements and heavy vehicle percentages. Therefore, the objective of this study is to estimate the PCE for heavy vehicles depending on various geometric elements. Entry capacity and PCE were estimated by the entry capacity equation in JRM and traffic simulator VISSIM, respectively. The results revealed that the entry capacity changes with different geometric elements and is significantly related to inscribed circle diameter. It was also concluded that PCE changes with increasing heavy vehicle percentages in the entering and circulating flows.</p>

DOI： 10.2208/jscejipm.75.i_1167

CiNii Research

記述言語：英語   出版者・発行元：公益社団法人 土木学会  

<p>Start-up lost time (SLT, hereinafter) is one of the basic parameters for evaluating the capacities of signalized intersections. In the urban area, intersections are closely spaced and traffic demand is high. Drivers' ambitions for the quick startup are demotivated by negative downstream traffic conditions, for example, limited available storage length, long queue and/or poorly coordinated traffic signals. The performance of upstream intersection is deteriorated including the growth in the SLT. In this paper, the influence of downstream conditions over SLT is analyzed by empirical study. The result indicates that SLTs at subject intersections are mainly influenced by downstream queue length, offset, segment length, and clearing vehicles. Short downstream segment length, long queue, positive offset, and long clearing time will lead to a high SLT value. Regarding this finding, the effect is further investigated by developing a new car-following model. The new model is built by improving the intelligent driver model and calibrated it with empirical data by a genetic algorithm. Through scenario simulation and comparison with empirical data, it is proved that the new model not only can reproduce the SLT increase under different downstream conditions but also have a good fit with real-world data.</p>

DOI： 10.2208/jscejipm.75.i_1121

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

<p>　ラウンドアバウトの幾何構造設計では，単に幾何構造要素の寸法を決定する仕様設計ではなく，安全性能照査型の手法が求められる．しかし，わが国では安全性能照査型の設計を行うための評価方法や評価指標はこれまで検討されていない．そこで本研究は，ラウンドアバウト幾何構造の安全性能評価指標として，事故の起きやすさを表す見落とし確率と，事故が起きた時の重度を示す衝突強度の積で表されるリスク指標を提案し，その算出方法を提示した．また，任意の幾何構造を対象とした数値シミュレーション結果に基づき，幾何構造条件からリスク指標を算出するためのモデル化を行った．その結果，とくに流入部接続角度が小さいと見落とし確率が高くなり，また偏差角が小さいほど衝突強度が高くなることが明らかになった．</p>

DOI： 10.2208/jscejipm.75.191

CiNii Research

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IATSS Research  

Signalized intersections are one of the key elements that play a vital role at road networks. The efficiency and safety levels of intersections can affect the operational performance of the whole system. In general, turning traffic, especially median-turning, has always been considered as the most problematic movement in the operation of intersections. This becomes more critical with high turning demand where exclusive turning lanes (single or double) can be assigned to provide larger capacities for these movements and to reduce conflicts with through traffic. However, improper treatment of median-turn lanes could create cross-maneuvering behavior which may limit the expected increase in capacity and create safety issues. Median-turning lane markings are commonly provided at intersections in Japan to guide drivers while turning which is expected to reduce the conflicts among turning traffic. Meanwhile, in the Philippines, exclusive median-turn lanes are installed at intersections without proper treatment which may contribute to the low mobility and safety levels. Therefore, this study evaluated the impact of inside intersection lane markings on the operation of median-turn lanes in terms of mobility and safety. The vehicle maneuver, speed and interactions between the turning traffic were utilized as essential components for the assessment. The empirical analysis shows that conflicting trajectories were present on double turn lanes without median-turn lane markings in the Philippines, which resulted to serious conflicts among the turning vehicles and negatively influenced the turning speed and saturation flow rate of the turn lanes. On the other hand, the turn lane markings in Japan, provided a positive impact to mobility and safety of the turning lanes. Moreover, it was also found that the geometric characteristics and traffic signal phasing scheme highly affects the capacity and safety condition of signalized intersections.

DOI： 10.1016/j.iatssr.2017.12.001

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Transportation Research Part A: Policy and Practice  

The selection of proper control types at intersections at the planning stage is an important concern considering the difficulty in comparing the performance of different control types. Therefore, several manuals proposed selection charts to guide traffic engineers in identifying the control strategy that yields to the lowest delay and the highest level of service. However, most of these methodologies consider only total major and minor street traffic flows. They do not necessarily suggest to investigate the impact of turning traffic and pedestrian flows, which limits the applicability of their recommendations. Thus, this study aims to propose a procedure to assess the selection of the optimum control strategies among two-way stop, roundabout and signalization using average intersection vehicle delay as the evaluation criterion. The impact of turning traffic on the major and minor streets as well as the impact of pedestrians are integrated into the developed analytical methodology for the estimation of average intersection vehicle delay. A typical layout of isolated four-leg two-way intersection is assumed for the model development. It is concluded that turning traffic and pedestrians play essential roles in the performance of intersections. As pedestrian flow increases, signal control becomes prevailing over the other control types.

DOI： 10.1016/j.tra.2018.08.039

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Transportation Research Part C: Emerging Technologies  

DOI： 10.1016/j.trc.2017.11.022

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Transportation Research Procedia  

Intersections, whether signalized, STOP controlled, or YIELD controlled form some of the main features that define interrupted flow facilities. In addition to the imposition to stop that comes with the red indication of traffic signals, other settings such as the cycle length and offsets have a great impact on the amount of delay encountered, and therefore the average travel speed. Improper settings are likely to bring about a reduction in the performance of the highway, and therefore it is important to forecast their potential impacts on the planned highways' performance. In this study, we examine the variation in the average travel speed along a hypothesized two-lane highway by changing the segment length, density of signalized intersections, cycle length, and offset settings. Results showed that average travel speed reduced with increased signalized intersection density, and that the network layout also had a significant impact on the travel speed. Furthermore, it was shown that based on the link length and the free flow travel time, the choice of cycle length and offset settings has a very significant impact on the travel speed.

DOI： 10.1016/j.trpro.2018.11.013

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Transportation Research Procedia  

Due to the advancement in technology, it is likely to witness a deployment of Autonomous Vehicles (AV) on the road in the near future. High technical capability of AVs is expected to create different behavioral settings than Human-Driven Vehicles (HDV), such as shorter reaction time and time headway. However, considering AV-HDV mixed traffic conditions in the process of the dissemination, radical behavioral settings of AV might have negative impacts on traffic flow. This paper investigates safety, efficiency and comfort impacts of AV on a single lane motorway considering different reaction time, time headway and percentage of AV in a vehicle platoon. Results of Monte Carlo simulation show that with increased percentage of AV, safety, efficiency and comfort can be improved as far as the time headway of AV is similar to HDV under the assumption that AVs have smaller reaction time than HDVs. However, it can be concluded that the smaller desired minimum time headway may cause the unsafe and uncomfortable condition with the longer reaction time. Therefore, the setting of AV should be carefully selected considering the relationship between the reaction time and the desired minimum time headway.

DOI： 10.1016/j.trpro.2018.11.035

Web of Science

Scopus

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

In this study, stochastic breakdown phenomena on a two-lane section of a Japanese urban expressway are analyzed and modeled. Because the bottleneck of the subject section is supposed to be a complex geometry with an on-ramp, a horizontal curve and an uphill, analysis is conducted not only by cross section but also by lane to understand the characteristics of breakdowns in detail. For such a detailed analysis, applicability and limitation of the detector data with different aggregation intervals are also considered. Through the analysis, it is found that about 40% of breakdowns in the section occur first on the shoulder lane; one of the causes would be higher merging traffic volume. The estimation of breakdown probability shows that the capacity of the median lane is about 300-veh/h greater than that of the shoulder lane. Furthermore, it is found that the discharge flow rate deteriorates as the elapsed time after breakdown increases, especially at the beginning of congestion.

DOI： 10.11175/eastsats.5.64

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p><tt>ラウンドアバウトでは，通常の十字交差点と異なり </tt>S <tt>字の走行軌跡が生じるため，安全性・円滑性の観点から適切な走行挙動が実現するような幾何構造設計が重要である．しかし我が国では，ラウンドアバウト特有の走行挙動特性と幾何構造の関係性は明らかになっていない．そこで本研究では，異なる幾何構造を有する </tt>7 <tt>箇所のラウンドアバウトにおいて，</tt>UAV(<tt>無人航空機</tt>)<tt>による走行挙動調査を実施し，幾何構造が走行挙動特性に与える影響について分析した．その結果，流入部の隅角部曲線半径と流出入部交差角度が，車両に加わる横方向加速度に対して重要な要素であることを明らかにした．さらに，過剰に大きい隅角部曲線半径や，流出入部交差角度が </tt>150°<tt>より小さい場合，車両に加わる横方向加速度が小さくなり，速度抑制が得られにくい構造であることを示した</tt><tt>． </tt></p>

DOI： 10.14954/jste.4.1_a_47

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

高速道路における渋滞現象は，その発生メカニズムや確率的特性，発生前後での交通容量の相違など，数多くの知見が蓄積されつつある．しかしながら，車線減区間のような車線利用特性の影響が大きい区間では，交通容量の低下は明らかであるものの未だ不明確な点が多く，詳細な分析が必要である．そこで本論文では，絞り込み形態が異なる複数の車線減区間を対象に，渋滞発生前後のメカニズムについて分析を行った．その中で，渋滞発生確率曲線の推定を行い，車線利用特性を踏まえた考察を行ったところ，渋滞発生確率は絞り込み車線が第一，登坂，合流車線の順に高くなることがわかった．要因として，第一車線の場合は渋滞発生前の車線利用の偏りが小さいこと，合流車線の場合は左からの追越が発生しているなど，車線利用特性の影響が大きいことを示した．

DOI： 10.2208/jscejipm.74.i_1411

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

平成26年の改正道路交通法の施行以降，ラウンドアバウトは全国各地で導入が検討されており，今後もさらなる普及が期待されている．ラウンドアバウトの幾何構造設計は様々な幾何構造要素の組合せを決定するプロセスであり，その設計プロセスにおいて幾何構造設計全体に対する安全性能評価が必要不可欠である．しかし我が国では，安全性能を評価するための具体的な方法や指標は検討されていない．そこで本研究では，海外の設計ガイドライン等を調査し，アメリカのFastest PathやスイスのDeflection Angleに基づく安全性能評価の考え方や特徴について把握した．また，海外の評価方法を用いて国内の既存ラウンドアバウトの幾何構造を評価し，我が国における適用性について議論した．

DOI： 10.2208/jscejipm.74.i_1037

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

ラウンドアバウトの導入検討に際しては，流入部の交通容量の確認が重要となるが，我が国では未だその事例が少なく，ラウンドアバウトの幾何構造が交通容量に与える影響が十分明らかになっていない．また，ラウンドアバウトの流入交通容量は，我が国ではギャップアクセプタンス確率に基づく推定式により算定することとしているが，その際に必要となる車頭時間パラメータに幾何構造諸元が与える影響も明らかになっていない．そこで本研究では，我が国のラウンドアバウトで得られた観測データを用いて，幾何構造諸元が流入交通容量に与える影響を分析し，幾何構造諸元と交通条件を説明変数とする車頭時間パラメータの推定式を提案した．そして，これに基づきラウンドアバウトの幾何構造諸元が流入交通容量に与える影響を定量的に明らかにした

DOI： 10.2208/jscejipm.74.i_1399

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<p><tt>わが国の無信号横断歩道では，横断者の安全・円滑な横断が確保されているとは言い難い現状にある．これに対して横断者の優先権を確保するため，近年，「二段階横断方式」すなわち道路中央部に設けられた交通島を利用して横断歩道を二段階で渡る方式が注目されている．しかし，わが国における適用事例はまだ限られており，効果を定量的に示すことが望まれる．本研究では，ビデオ観測データに基づき，横断者の横断判断に対して，横断所要時間および接近する車両の位置と速度が与える影響を分析した．そのうえで，二段階横断方式適用時のクリティカルギャップの変化を，横断者の車両交通流に対するギャップ選択モデルにより推定した．また，このクリティカルギャップを用いて横断者の平均遅れを計算することにより，円滑性の向上効果を定量的に評価した．</tt></p>

DOI： 10.14954/jste.4.1_a_8

CiNii Research

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Transportation Research Record  

Traffic accidents constitute a serious social problem. Thus, it is essential to identify and remove the risk factors affecting traffic accidents to enhance traffic safety at intersections. This study identified and quantified the main factors influencing traffic accident risk at signalized intersections to propose effective countermeasures. Google Earth was used to collect numerical data related to the geometric attributes of intersections in three regions in Japan: Kagawa, Shiga, and Aichi. A lognormal hurdle model that considered regionality and geometric attributes was then used to quantify factors influencing the risk of traffic accidents involving various types of collisions. The results indicate the existence of significant regional differences in the geometric attributes of intersections in those regions. The findings reveal that intersection size (indicated by the distance between stop lines), length of crosswalks, and setback distance of crosswalks generally and significantly influence all collision risk types; in addition, a compact intersection lowered the risk of all collision types. And in most cases, regional dummy variables were statistically significant. This finding suggests that in addition to intersection geometric attributes, regional differences in some factors influenced collision risk. Thus, it could be reasonably assumed that regionality stemmed from differences in driving characteristics.

DOI： 10.3141/2659-08

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Transportation Research Procedia  

Heavy vehicles behave differently from ordinary passenger cars due to their characteristics such as larger size. Thus, it should be carefully considered when designing a road facility or evaluating its performance. This paper aims at analyzing the characteristics of heavy vehicle behavior at roundabouts under the Japanese situations. By using field data observed at a single-lane roundabout in Japan, an empirical analysis on headway parameters was conducted for examining the characteristics of heavy vehicles. It was confirmed that the headways which are formed by heavy vehicles are commonly greater than those formed by passenger cars only. The results in this paper are expected to be used for roundabout performance evaluations such as roundabout entry capacity estimation.

DOI： 10.1016/j.trpro.2017.05.176

Web of Science

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Transportation Research Procedia  

This study aims at formulating appropriate ranges of road spacing shown with the travel speeds in the classification for a two-level grid network. The appropriate range is determined by the maximum and minimum values. The minimum road spacing is determined so that the target travel speed can be achieved in operational stage. The maximum road spacing is calculated for satisfying the two conditions in which 1) target travel time can be achieved and 2) travel distance of higher target travel speed greater than that of lower target travel speed. Within the obtained range of road spacing, the maximum travel distance between Community Center (CMC) and Lower Urban Center (LUC) is calculated. Accordingly, it become possible to obtain the required scenario of target travel speed and road spacing in the subjective regions, for the assumed level of target travel time achievement.

DOI： 10.1016/j.trpro.2017.05.266

Web of Science

Scopus

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Accurate estimation of travel speed along a transport facility is necessary in order to ensure that the facilities meet the required performance. In this paper, the performance of the Highway Capacity Manual travel speed model is checked for Japanese roads. Then, a travel speed estimation model is developed from data collected along a road section in Hamamatsu City, Japan. The model provides an estimate of the average travel speed along a road section by inputting demand flow rates, section length, number of signalised intersections, signalised intersection density, and the number of access points along the road in the travel direction. It is found that the travel speed slightly increases with increased section length, and decreases with increased access points and higher number and density of signalised intersections.

DOI： 10.11175/easts.12.1604

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

ラウンドアバウトにおけるクリティカルギャップは，流入交通容量の推定に必要であるほか，ドライバーの流入判断を安全面から評価する際にも用いることができると期待され，実観測データに基づいてこれを適切に推定することは極めて重要である．そこで本論文では，諸外国における代表的なクリティカルギャップ推定手法をレビューすると共に，これらを日本のラウンドアバウトに適用し，比較を行った．これにより，手法による推定結果の差異と観測サンプル数の偏りとの関係などが把握された．また，日本で一般に用いられるRaff's method以外の手法を用いることで，クリティカルギャップの代表値だけでなく，その分布のバラツキも考慮して，ドライバーの流入判断挙動を比較することが可能になった．

DOI： 10.2208/jscejipm.73.i_1243

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

信号交差点における横断歩行者と左折車との交錯を抑制するための対策として、歩車分離式信号制御や歩行者先行現示(Leading Pedestrian Interval; LPI)方式が挙げられる。このうちLPIとは、歩行者青を車両青よりも数秒先に表示し、先行する一部の時間のみ歩行者と車両を分離するものである。この方式は、安全性と円滑性の観点から、四現示など歩行者と左折車を同一現示で処理する制御方式と完全歩車分離式との間に位置付けることができる。本研究では、これらの3つの信号制御方式について、歩行者および車両遅れ時間、車両のDegree of saturation、交通容量や、歩行者の暴露時間などの交差点性能に関する比較分析を行い、これより特にLPIの適用範囲や歩車分離方式との境界条件などを明らかにした。

DOI： 10.14954/jste.3.5_11

CiNii Research

CiNii Research

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Inside intersection pavement markings category in Japan and Philippines are different, and the difference of its impact to mobility performance are still unknown. Left-turn lanes (right-turn in Japan) is one of key movements in urban signalized intersections and their capacity must be maximized. This paper aims to investigate the difference of the mobility performance of the right-turn guide lines in Japan and Yellow-Box pavement markings in the Philippines in terms of saturation flow rate, trajectory variation and speed. The analysis reveals that the turn guide lines are effective in achieving small turning vehicle trajectory variation and high saturation flow rate which are affected by the traffic signal phasing and the geometric layout of the turn lanes of the signalized intersection. The absence of guide lines of yellow box pavement markings creates cross-maneuvering behavior that lower the saturation flow rate of the turning lane.

DOI： 10.11175/easts.12.1637

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

This study aims to identify influencing factors of traffic accidents on Japanese major roads through factor analysis and regression analysis for each accident type, considering their characteristics as rare events. The database consists of a five-year accident record and relevant road traffic condition data on major road sections in Aichi Prefecture, which includes the third largest conurbation area of Japan. From the results of the factor analysis, a trend of high accident rates in broad urban arterials is confirmed, and rear-end or side collisions are widely distributed in suburban areas. From the regression analysis, results reveal that the degree of impact by traffic volume is dependent on accident type, and suggests that several factors related to visibility have an influence on turning and side collisions. The study suggests that improving the quality of traffic flow on major roads by ensuring proper intersection spacing is important for establishing a safer road network.

DOI： 10.11175/eastsats.4.392

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Besides circulating flow, pedestrian flow is another key conflict stream that significantly influences roundabout entry capacity. Due to limited space in Japan, several standard designs such as a physical splitter island cannot always be installed at the roundabout entry/exit. The impact of several influencing factors on entry capacity such as splitter islands was examined by applying a microscopic simulation to our previous research. A regression model was proposed based on the simulation results, which assumed that vehicles yielded to all pedestrians at the beginning of the crosswalk. In this paper, the regression model was validated using field data observed in Japan. The regression model was improved by adding a parameter to reflect drivers' compliance with pedestrians. The validation results indicate that the improved model shows good fitness to the field data and the results imply that roundabout geometry and traffic flow composition significantly influence entry capacity.

DOI： 10.11175/eastsats.4.350

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

2014年の道路交通法改正に伴いラウンドアバウトの導入が各地で検討される中で，流入交通容量に対する大型車の影響を定量化することは，重要な検討課題である．そこで本研究は，日本のラウンドアバウトにおける大型車の乗用車換算係数（PCE）を推定することを目的とする．飽和状態のラウンドアバウトを実観測することは困難なため，実観測可能な乗用車・大型車のミクロ車両挙動に基づいてキャリブレーションした交通シミュレータを用いて，環道部・流入部どちらか片方のみに大型車が混入する場合の流入交通容量を計測し，大型車の乗用車換算係数（PCE）を推定した．その結果，大型車の乗用車換算係数は，環道部より流入部において大きいことが示された．また，環道部・流入部の両方に大型車が混入する場合の流入交通容量も推定可能となった．

DOI： 10.14954/jste.2.6_11

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

今後わが国では，生活・都市機能の集約した拠点間を効率的に連絡するため，道路ネットワークを機能階層型に再編してゆくことが重要である．そこで本研究では，拠点間連絡性能として目標旅行時間が与えられた場合に，これを連絡する道路ネットワークの望ましい階層構成を検討することを目的とする．道路ネットワークの階層構成は階層数，階層別目標旅行速度，道路間隔，下位階層との接続間隔の組み合わせからなり，沿道出入や階層間接続で生じる遅れなどが旅行速度に及ぼす影響を考慮してその代替案が構築される．今回は東海道地域を対象に，階層構成代替案において達成される拠点間旅行時間を推定し，特に自専道の発達していない半島や山間部の集落から生活拠点・高次都市拠点への連絡に対して，高速の階層を設定することの重要性が定量的に示された．

DOI： 10.2208/jscejipm.72.i_939

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

交錯する対向直進車と同一現示内で右折が許される丸青時のギャップアクセプタンス挙動は，信号交差点の安全性を検討する上での重要項目の 1 つである．本研究では，多車線交差点におけるギャップアクセプタンス挙動に着目し，ギャップ判断の意思決定プロセスを整理した上で，ギャップを形成する直進車の走行位置を考慮したギャップアクセプタンス判断を二項ロジットモデルにより表現した．モデル分析結果より，ギャップアクセプタンス判断には，ギャップ時間や対向直進車の速度などの要因に加え，ギャップ形成車両の車線走行位置の影響を受けていることが定量的に示された．さらに構築したモデルに基づく計算結果から，対向直進車線数が 1 車線である場合と比較して，ギャップ形成車両の配列によりクリティカルギャップの値が増減する可能性が示唆された.

DOI： 10.14954/jste.2.2_a_85

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

信号交差点における歩行者信号の適切な設定は、利用者の安全性と円滑性の確保に極めて重要である。 これらを評価するには、信号表示の時間経過に伴った横断歩行者の存在位置を知ることが有益である。 そこで本研究では、歩行者青の経過時間、待機時間長、横断歩道長と歩行者交通量等が歩行者の存在位置分布に及ぼす影響を分析し、これらを推定するモデルを構築した。その結果、歩行者青の序盤に、横断歩道手前で待機する歩行者がまとまって横断歩道に進入し、時間の経過とともに起点から遠くなり、位置分布が広がっていくことが示された。横断歩道が長いほど、待機時間長が短いほど、位置分布のバラツキが大きくなる傾向がある。さらに、推定したモデルを用いて、歩行者先行現示(LPI)設定への適用方法および適用可能な条件について検討した。

DOI： 10.14954/jste.2.2_a_183

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

一般道で発生する交通事故の半数以上は交差点，および交差点付近で発生している．交通安全性を向上させるためには，交差点における交通事故リスク要因を定量化し，適切な交差点改良，あるいは交通運用を図ることが求められる．しかしながら，交差点毎にその幾何構造的特徴を数値化したデータベースはこれまでに整備されておらず，交通事故リスク要因の定量化がなされていないのが現状である．そこで，本研究ではGoogle Earthを用い，停止線間距離やアプローチの交差角度，ガードレールの有無や縁石の有無，車線運用や路面標示状況，沿道土地利用状況などのデータを数値化し，類型毎の事故リスクとの関係をポアソン回帰モデルにより分析した．その結果，交差点のコンパクト化が事故リスクの軽減に極めて有効であることなどが明らかとされた．

DOI： 10.2208/jscejipm.72.368

CiNii Research

CiNii Research

記述言語：日本語   出版者・発行元：IEEE Transactions on Intelligent Transportation Systems  

Pedestrian-vehicle conflicts are considered one of the most common safety problems at signalized intersections. In Japan, the pedestrian flashing green (PFG) is considered a safe time interval for pedestrians at crosswalks to finish crossing before conflicting vehicle streams are released. In most common phasing schemes, pedestrians have the right-of-way along with left-turning vehicles (in left-hand traffic). By law, pedestrians should not enter a crosswalk during the PFG. However, many of them rush into crosswalks without necessarily heeding approaching turning vehicles, which could increase the probability of severe conflicts. The objective of this paper is to analyze and model the probabilistic behavior of pedestrians after the onset of the PFG, which contains the pedestrians' decision of whether to give up crossing, as well as the pedestrian speed distribution. Empirical data analysis showed that longer crosswalks lead to significantly higher pedestrian stop probabilities. Furthermore, there is a significant difference between the pedestrians' speeds in the first and second halves of crosswalks. The results of a Monte Carlo simulation showed that the estimated models closely represent the overall stochastic behavior of the pedestrians from the onset of the PFG until the completion of crossing.

DOI： 10.1109/TITS.2014.2346154

Web of Science

Scopus

記述言語：日本語   出版者・発行元：Transportation Research Record  

At roundabouts, the main streams that conflict with entry flow and have a significant effect on entry capacity are circulating flow and pedestrian flow. Pedestrian impact is estimated with an adjustment factor ( fped) in existing methods that were developed under standard roundabout designs, such as a physical splitter island at entry and exit. However, available space may limit these geometric designs in some locations (e.g., in Japan), and, as a result, the impact of driver and pedestrian behaviors on entry capacity probably changes. In a microscopic approach, entry vehicles cross pedestrian flow through available pedestrian gaps. Therefore, gap acceptance behavior is used to reproduce conflict with pedestrians. This analysis aimed to estimate roundabout entry capacity that considers conflict with pedestrians by gap acceptance behavior as well as several influencing factors, including presence or absence of a physical splitter island and the farside pedestrian yield rate (i.e., number of drivers yielding to the total farside pedestrian demand). Entry capacity was estimated two ways, with simulation analysis and a theoretical model. The estimated entry capacity results from the two approaches were compared, and the limitations of each approach were interpreted. Results from the two proposed approaches also were compared with those from the existing fped model that was applied in Highway Capacity Manual 2010 (referred to as HCM fped). Findings imply that HCM fped is not appropriate for Japanese situations. Both proposed approaches are expected to be used in the planning and design stages for roundabout implementation not only in Japan but also in other countries that must consider space limitations and pedestrians.

DOI： 10.3141/2517-07

Web of Science

Scopus

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Quantifying effects of crosswalk length and signal timing on pedestrians' presence position and timing is an important requirement for evaluating the probability of conflict. It can be utilized to provide a rational safety assessment and improve existing operational policies at signalized intersections. This study investigates the effects of crosswalk length and pedestrian green time on the spatiotemporal probability of pedestrian presence. It was found that the longer pedestrian green time and crosswalk length leads to the wider distribution of pedestrian presence probability. In addition, a surrogate safety measure for assessing pedestrian safety is proposed by utilizing the pedestrian presence probability model.

DOI： 10.11175/easts.11.1403

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

近年，我が国では，地域の自発的な取り組みによりラウンドアバウトの社会実験や導入事例が増え，平成25年6月には道路交通法の一部を改正する法律が成立し，ラウンドアバウトが環状交差点として法的に位置付けられた．一方，未だラウンドアバウトの導入事例が少ないため，ラウンドアバウトを導入する際に必要となる，自動車や横断歩行者・自転車の交通状況の実測値を踏まえた交通容量上の判断基準は明確になっていないのが現状である．本研究では，ラウンドアバウト運用のされている既存円形交差点やラウンドアバウト社会実験での観測データを用いて，実現交通量の特性を分析した上で，軽井沢町六本辻ラウンドアバウトで観測された交通容量に関する考察を行うとともに，提案されている横断歩行者等を考慮した流入部交通容量推定式との比較を行う．

DOI： 10.2208/jscejipm.71.i_1017

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

本論文では，交通事故削減に向けた効率的な安全対策実施を目標として，道路交通や社会環境条件と事故発生との関係について事故類型別に統計モデル分析を行った．分析にあたっては，事故データに道路交通状況等の各種情報をGIS上で付与したデータベースを構築し，事故発生頻度を被説明変数とした負の二項分布回帰分析より影響要因の特定を試みた．分析結果より，幹線道路の事故発生頻度と混雑時平均旅行速度や交差点間距離が密接な関係にあることや，非幹線道路では道路幅員や用途地域等の要因が事故類型間で異なることを示した．さらに，非幹線道路の事故は旅行速度の低い幹線道路に近い位置で多発する傾向を示唆した．分析結果をふまえ，幹線道路の円滑性向上や階層化された道路ネットワークの再構築による安全性向上について考察した．

DOI： 10.2208/jscejipm.71.i_889

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

<tt>階層型道路ネットワーク計画では，個別道路の設計・運用に際して目標となる階層数・階層別目標旅行速度・道路間隔について，拠点配置特性や需要特性，目標旅行時間を考慮して適切に設定することが重要である．本論文では，これらの値を目標旅行時間達成状況と建設費用に基づいて設定する手法を提案 する．ここでは，トラフィック機能とアクセス機能のトレードオフ関係から変数の組み合わせが現実的であり，かつ比較検討可能なシナリオ数とするため，接続階層間では目標旅行速度比と道路間隔比の間に比例関係を仮定し，さらに目標旅行速度が最低と最高となる階層をそれぞれ所与とする．この手法のもと，典型的な拠点配置，格子状ネットワークを想定したケーススタディを行い，階層数が拠点間距離別旅行時間や建設費用に及ぼす影響について考察を行った.</tt>

DOI： 10.14954/jste.1.2_a_107

CiNii Research

記述言語：日本語   出版者・発行元：一般社団法人 交通工学研究会  

従来用いられているラウンドアバウト流入交通容量の推定手法は，海外で標準的な道路構造や利用者挙動を前提としているが，日本においては用地制約等の都合上，流出入部分離島が必ずしも設置されないことも多く，これにより横断歩行者挙動やその交通容量への影響が海外諸国と異なる場合がある．本論文では，日本における各種条件が流入交通容量に与える影響についてシミュレーション分析を行い，それらの結果を用いて流入交通容量を推定する重回帰モデルを構築した．そして，これを軽井沢町六本辻ラウンドアバウトで観測されたデータを用いて検証するとともに，既往の手法との比較を行った．その結果，提案する手法では高い精度で各種条件における流入交通容量を推定可能であるのに対して，既往の方法では過大推計となることが示された．

DOI： 10.14954/jste.1.5_19

CiNii Research

記述言語：日本語   出版者・発行元：Transportation Research Part C: Emerging Technologies  

Limited pedestrian behavior models shed light on the case at signalized crosswalk, where pedestrian behavior is characterized by group or individual evasion with surrounding pedestrians, collision avoidance with conflicting vehicles, and response to signal control and crosswalk boundary. This study fills this gap by developing a microscopic simulation model for pedestrian behavior analysis at signalized intersection. The social force theory has been employed and adjusted for this purpose. The parameters, including measurable and non-measurable ones, are either directly estimated based on observed dataset or indirectly derived by maximum likelihood estimation. Last, the model performance was confirmed in light of individual trajectory comparison between estimation and observation, passing position distribution at several cross-sections, collision avoidance behavior with conflicting vehicles, and lane-formation phenomenon. The simulation results also concluded that the model enables to visually represent pedestrian crossing behavior as in the real world. © 2014 Elsevier Ltd.

DOI： 10.1016/j.trc.2014.01.007

Web of Science

Scopus

記述言語：日本語   出版者・発行元：Transportation Research Record  

Entry capacity is one of the most important indexes for performance evaluation of roundabouts. In addition to circulating vehicles, pedestrian flow is another key conflicting stream that has a significant impact on entry capacity. Pedestrian impact is considered by an adjustment factor in the Highway Capacity Manual 2010. However, this method is limited in estimating pedestrian impact by several influencing factors [e.g., pedestrian approaching side, farside pedestrian recognition rate (FPRR) of drivers, and physical splitter island] that are considered to be significant for representing the characteristics of the Japanese situation. The impacts of these influencing factors are examined by microscopic simulation in this study. Results from the simulation study showed that under the condition without a physical splitter island, entry capacity was reduced more significantly when more pedestrians were from the farside of the crosswalk, whereas capacity relatively increased with decreasing FPRR. Moreover, entry capacity was also increased after the installation of a physical splitter Island. The significance and the necessity of a physical splitter island were demonstrated in this analysis for roundabout design and operation in Japan. This research also showed that those influencing factors (i.e., pedestrian approaching side, FPRR, and physical splitter island) should be coasidered in entry capacity estimation.

DOI： 10.3141/2461-14

Web of Science

Scopus

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

信号交差点における右折関連事故は依然として高い割合にあり，右折車両の挙動を分析することは交差点の安全性を検討する上で極めて重要である．本論文では，他の道路利用者の影響を比較的受けない，直進・左折と分離された右折専用現示における右折車両挙動に着目し，道路構造や交通運用が各挙動に与える影響を分析する．分析結果より，専用現示における右折車両挙動には交差角度や停止線セットバック量といった道路構造が強く影響していることを示す．さらに，交通安全上の課題に対する対策立案や対策が挙動に及ぼす正負の効果を把握するため，一連の各挙動とその影響要因を整理することの必要性を述べる．最後に，交差点の安全性評価において，ミクロシミュレータ活用によるメリットや代替性安全性指標を包括的に評価することの必要性について考察する．

DOI： 10.2208/jscejipm.70.i_1013

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

信号交差点における横断歩行者の歩行速度特性を知ることは，歩行者の安全性の向上に極めて重要である．そのため，横断歩道の幾何構造および信号現示などによる横断歩行速度の変化を定量的に評価する必要がある．そこで本研究では，様々な横断歩道長や歩行者青時間長の横断歩道における歩行者青(PG)時の横断歩行速度を，横断の前半・後半に分けて分析し，これらを推定するモデルを構築した．その結果，横断歩道長が長くなるほど，また青時間開始から時間が経つほど，横断歩行速度が速くなることがわかった．さらに，これを既存の歩行者青点滅(PF)時間を対象としたモデルと比較し各説明変数の感度分析を行ったところ，青点滅時の方が全体的に横断歩行速度が速く，横断歩道長や横断開始タイミングに対する感度も高い傾向が見られた．

DOI： 10.2208/jscejipm.70.i_1031

CiNii Research

CiNii Research

出版者・発行元：Advances in Transportation Studies  

Pedestrian safety improvement at signalized intersections remains a critical issue. The major threat comes from frequent interaction with turning vehicles, especially left-turners (left-hand traffic system). This study gains insights into how surrogate safety measure (SSM) can be utilized for pedestrian versus left-turning vehicle conflict assessment, and although a small step, how to relate SSM to limited crash records for crash risk estimation. Based on the video data collected at several crosswalks in Nagoya City, Japan, SSMs, i.e., Post Encroachment Time (PET) and vehicle passing speed at conflict point were extracted for analysis. PETs were estimated for both near-side and far-side approaching pedestrians by identifying the potential conflict points and considering the physical size of left-turning vehicles. The effectiveness of SSMs to reflect the impact of site-specific geometric characteristics and operational conditions upon conflict risk has been demonstrated. Furthermore, crash risk estimation models were developed by using Poisson regression methods based on mean PET, the number of short PETs per hour and average vehicle passing speed at conflict point at each crosswalk. It demonstrates that high turning speed, in conjunction with higher frequency of short PETs result in higher crash rates.

DOI： 10.4399/97888548735445

Scopus

出版者・発行元：Journal of Modern Transportation  

This study aims at identifying crash-influencing factors by facility type of Nagoya Urban Expressway, considering the interaction of geometry, traffic flow, and ambient conditions. Crash rate (CR) model is firstly developed separately at four facility types: basic, merge, and diverge segments and sharp curve. Traffic flows are thereby categorized, and based on the traffic categories, the significances of factors affecting crashes are analyzed by principal component analysis. The results reveal that, the CR at merge segment is significantly higher than those at basic and diverge segments in uncongested flow, while the value is not significantly different at the three facility types in congested flow. In both un-and congested flows, sharp curve has the worst safety performance in view of its highest CR. Regarding influencing factors, geometric design and traffic flow are most significant in un-and congested flows, respectively. As mainline flow increases, the effect of merging ratio affecting crash is on the rise at basic and merge segments as opposed to the decreasing significance of diverging ratio at diverge segment. Meanwhile, longer acceleration and deceleration lanes are adverse to safety in uncongested flow, while shorter acceleration and deceleration lanes are adverse in congested flow. Due to its special geometric design, crashes at sharp curve are highly associated with the large centrifugal force and heavy restricted visibility. © The Author(s) 2013.

DOI： 10.1007/s40534-013-0024-9

Scopus

記述言語：日本語   出版者・発行元：Transportation Research Part C: Emerging Technologies  

Analytical evaluation techniques for the safety performance of signalized intersections are applicable to limited scenarios and conditions, whereas simulation-based analysis tools are very flexible and promising. This study is part of intensive efforts to develop a microscopic simulation model for the safety assessment of signalized intersections. One important aspect of analyzing driver maneuver is vehicle paths. Broadly varying paths may result in widely distributed potential conflict points with other movements, which may affect the occurrence probability of severe conflicts. Therefore, this study aims to develop a technique to reproduce the variations in the paths of turning vehicles, considering intersection geometry, vehicle type, and speed. Several signalized intersections in Nagoya City, Japan, with various traffic and geometric characteristics were videotaped. The analysis revealed that the paths of right-turning vehicles (left-hand traffic) are more sensitive to the vehicle speed and turning angle whereas those of left-turning vehicles are more sensitive to the intersection corner radius, turning angle, and vehicle speed. For modeling individual vehicle paths, this study applies the Euler-spiral-based approximation methodology where each trajectory is fitted by an entering Euler spiral curve followed by a circular curve and an exit Euler spiral curve. The proposed models are unique since they provide a realistic and rational representation of the variations in turning vehicles' paths inside intersections. © 2012 Elsevier Ltd.

DOI： 10.1016/j.trc.2012.09.006

Web of Science

Scopus

記述言語：日本語   出版者・発行元：Accident Analysis and Prevention  

Pedestrian-vehicle conflicts are considered as a common safety problem at signalized intersections. The threat to pedestrian safety is mainly related to the interaction with turning vehicles, especially left-turners (left-hand traffic system). This study aims to analyze the lag/gap acceptance behavior of left-turners considering pedestrian movement at signalized crosswalks. Furthermore, the severity of pedestrian-vehicle conflicts is addressed by analyzing vehicle speeds at the conflict points. User behavior at several signalized intersections in Japan is observed by using video cameras. It is assumed that pedestrian movements have their origin at either the near-side (the side of the exiting vehicular traffic) or far-side of the crosswalk. Accepted/rejected lags and gaps are extracted, classified depending on the direction of pedestrian movement, and modeled by using Cumulative Weibull distribution function. The results show that drivers tend to accept shorter lags/gaps between near-side pedestrians compared to far side pedestrians. Furthermore, drivers tend to accept short lags while being conservative about short gaps. Simultaneously vehicles clear the conflict area with significantly higher speeds when accepting lags with single pedestrians. This indicates that the conflicts that occur at low pedestrian demand levels are more severe compared to those at high demand levels. © 2012 Elsevier Ltd.

DOI： 10.1016/j.aap.2012.04.006

Web of Science

Scopus

PubMed

記述言語：日本語   出版者・発行元：Transportation Research Record  

When the breakdown probability on expressways is being modeled, the identification of breakdowns is a decisive issue. To date, most identification methods have treated all lanes of the main line as one unit; these methods have been conducted mainly by checking the aggregated data of the cross section. However, this cross section-based method oversimplifies breakdown identification for expressway facilities, such as diverge sections, on which preferences for lane usage differ significantly. Therefore, a lane-based method is proposed to identify breakdowns in each lane; the timing of the breakdown is determined by a critical speed, which is optimized by obtaining the most significant speed reductions that accompany the breakdown. The proposed lane-based method is applied to four bottlenecks at diverge sections on intercity expressways in Japan. The superiorities of the lane-based method are as follows. First, the method can identify and exclude semicongested cases, in which some lanes are congested and others are not. At a diverge section of the Toyota junction in Japan, 15 semicongested cases were identified by the lane-based method from the 198 breakdowns identified by the cross section-based method. Second, the timing of a breakdown can be appropriately determined, as it was for 34 cases on this diverge section. These superiorities significantly improve the accuracy of extracted breakdown flow rates, which are underestimated by the existing cross section-based method. The breakdown probability is modeled with the lane-based method on the extracted breakdown flow rates, and the impacts of traffic condition characteristics are discussed. The diverge rate and the lane utilization rate are found to have significant impacts on the breakdown probability at diverge sections.

DOI： 10.3141/2395-10

Web of Science

Scopus

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

This study aims at developing a crash risk estimation model (CREM) considering the interaction of geometry, traffic flow and ambient conditions for basic segments of Nagoya Urban Expressway. A matched case-control study is firstly designed separately for three traffic conditions; low-density, high-density uncongested and congested regimes. Based on these case-control samples, conditional logistic regression is then applied and the CREM is finally developed. The results reveal that the model has statistical significance and acceptable goodness-of-fit, with 86.6%, 80.5% and 70.2% of predictive performance for each of the three traffic conditions, respectively. Regarding crash influencing factors, with the increase of traffic density, the significance of horizontal geometry affecting crash becomes lower. In contrast, the contribution of vertical geometry to crash risk is on the rise. Meanwhile, the effect of average speed on crashes gets more significant. Besides, nighttime or holiday can increase the relative risk compared to daytime or weekday, respectively.

DOI： 10.11175/easts.10.1916

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

This paper proposes an approach to model the gap choice behavior of merging vehicles under various traffic flow conditions at urban expressway merging sections in Nagoya, Japan. The gap choice is classified into three patterns denoted direct, yield and chase merging. Empirical analysis shows that mainline traffic conditions significantly affect the proportion of gap choice. In addition, yield and chase choices result in further merging position compared to direct one. This fact is necessary to be considered in order to design the acceleration lane to meet driver behavior under relevant operational traffic flow conditions. TTC is adopted as an index to determine the threshold of choosing a merging pattern. The results show that the thresholds of choosing direct/yield or chase, continue to chase or not and direct or yield are 4.3, 3.2 and 5.4 seconds, respectively. The gap choice behavior is modeled by applying binary logit model. The results reveal that relative speed and space gap, traffic conditions, acceleration lane length, and remaining distance significantly affect the gap choice behavior of merging drivers.

DOI： 10.2208/jscejipm.69.i_881

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Existing signal control strategies do not consider pedestrian flows in optimizing signal parameters, which may impose significant delays on pedestrians. This study aims to investigate the rationality and effectiveness of designing signal coordination for pedestrians. A numerical case study in Japan is analyzed. Field survey is conducted to collect the geometric characteristics, signal timings and vehicular traffic condition information. In a parallel approach, the performances of signal coordination for vehicular and pedestrian traffic are estimated by using the vehicular traffic simulation tool Synchro/SimTraffic and the pedestrian simulation tool NOMAD. The results showed that the coordination for the major pedestrian flow led to a significant reduction in average delay (15%). Generally, it is concluded that the effectiveness of pedestrian signal coordination is not guaranteed but depends on the relationship between pedestrian platoon dispersion and the signal cycle length.

DOI： 10.11175/eastsats.2.223

CiNii Research

出版者・発行元：IATSS Research  

Improving pedestrian safety at intersections remains a critical issue. Although several types of safety countermeasures, such as reforming intersection layouts, have been implemented, methods have not yet been established to quantitatively evaluate the effects of these countermeasures before installation. One of the main issues in pedestrian safety is conflicts with turning vehicles. This study aims to develop an integrated model to represent the variations in the maneuvers of left-turners (left-hand traffic) at signalized intersections that dynamically considers the vehicle reaction to intersection geometry and crossing pedestrians. The proposed method consists of four empirically developed stochastic sub-models, including a path model, free-flow speed profile model, lag/gap acceptance model, and stopping/clearing speed profile model. Since safety assessment is the main objective driving the development of the proposed model, this study uses post-encroachment time (PET) and vehicle speed at the crosswalk as validation parameters. Preliminary validation results obtained by Monte Carlo simulation show that the proposed integrated model can realistically represent the variations in vehicle maneuvers as well as the distribution of PET and vehicle speeds at the crosswalk. © 2012 International Association of Traffic and Safety Sciences.

DOI： 10.1016/j.iatssr.2012.03.002

Scopus

記述言語：日本語   出版者・発行元：Transportation Research Record  

Because of traffic accidents at signalized intersections, improvement in the design of geometric layouts and operations of intersections is needed. Traffic simulation provides an innovative approach to assessing the safety performance of various layouts and operational policies of signalized intersections. A microscopic simulation model was developed to assess the safety of signalized intersections. The proposed simulation model integrates many key behavioral models of road users, such as the stop-go decision at the onset of a yellow light, turning paths, turning speeds, start-up response time, and pedestrian gap acceptance models. The main feature of these empirical models is their consideration of the stochastic behavior of road users. Furthermore, these models are sensitive to the layout and operation of signalized intersections. This paper discusses how conflicts are presented inside the simulation by demonstrating the mechanism of one of the conflicts. Model validation and a case study were conducted. The validation results show that the simulation model reasonably represents the occurrence of conflicts at signalized intersections, which proves that the proposed model can be a reliable approach to safety assessment. A case study compares the performance of compact intersections with wider layouts. The simulation results show trends in safety improvements, although a general conclusion cannot be made.

DOI： 10.3141/2316-14

Web of Science

Scopus

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

道路の機能に応じたサービスを提供する階層型ネットワークの概念は，国内外を問わずその重要性が認識されてきた．特にわが国では，幹線道路の混雑や生活道路における通過交通といった課題解消のため，実用展開に向けた議論がおこなわれている．しかし，階層型ネットワーク実現の鍵となる交差形式の設定が，個別の道路やネットワーク全体の性能に及ぼす影響については，計画段階においては定量的に検証されてこなかった．本論文では，利用者均衡配分に交差点遅れを組み込むことでこれを明示的に評価可能な手法を構築し，格子状の仮想ネットワークを用いて検証した．その結果，機能的階層化の実現には幹線道路における交差点遅れの軽減が重要であることと，これが実現した場合，生活道路における交通静穏化対策も有効的に機能することが示された．

DOI： 10.2208/jscejipm.68.i_751

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

ラウンドアバウトは，安全でエコな平面交差部の制御方式として注目されており，日本でも実用展開に向けた動きが高まりつつある．ラウンドアバウトは，交差点進入時に必ずしも停止を必要としないため，アイドリング時や発進時の燃料消費が抑えられると考えられる．しかしラウンドアバウトの実地導入経験が少ない我が国では，ラウンドアバウト走行時の環境負荷量を推定し，信号交差点などと比較を行った研究成果は報告されていない．<br>本稿は，実信号交差点および模擬ラウンドアバウトにおいて行われたプローブ走行調査結果から，それぞれのCO₂排出量を推定し比較を行ったものである．その結果，ラウンドアバウトでは急な発進が少なく，停止時間も短いことから，信号交差点と比較してCO₂排出量が抑えられることが明らかとなった．

DOI： 10.2208/jscejipm.68.i_1253

CiNii Research

出版者・発行元：International Journal of Intelligent Transportation Systems Research  

This study intends to investigate operational performance of the group-based signal control approach (GA) in Japan. A cycle-based stochastic approach incorporating the HCM 2000 delay model and Monte Carlo simulation was proposed. To facilitate its application, extensive field data was collected at 11 typical intersections in Germany and Japan to understand the variability of input variables and their correlations. A series of case studies were eventually conducted to investigate the applicability of GA under various conditions, i. e., degree of saturation (DS), split ratio (SR), and the coefficient of variation (COV) of traffic demand. Conclusions supported that the operational performance of GA deteriorated with increasing SR and decreasing DS. GA is apparently advantageous for SRs less than 0.8, COVs less than 0.2, and optimum cycle lengths greater than 90 s. © 2011 Springer Science+Business Media, LLC.

DOI： 10.1007/s13177-011-0028-y

Scopus

出版者・発行元：Computer-Aided Civil and Infrastructure Engineering  

This article describes the development and implementation of adaptive transit signal priority (TSP) on an actuated dual-ring traffic signal control system. After providing an overview of architecture design of the adaptive TSP system, the article presents an adaptive TSP optimization model that optimizes green splits for three consecutive cycles to minimize the weighted sum of transit vehicle delay and other traffic delay, considering the safety and other operational constraints under the dual-ring structure of signal control. The model is illustrated using a numerical example under medium and heavily congested situations. The findings from a field operational test are also reported to validate and demonstrate the developed TSP system. At a congested intersection, it is found that the average bus delay and average traffic delay along the bus movement direction were reduced by approximately 43% and 16%, respectively. Moreover, the average delay of cross-street traffic was increased by about 12%. © 2010 Computer-Aided Civil and Infrastructure Engineering.

DOI： 10.1111/j.1467-8667.2010.00677.x

Web of Science

Scopus

記述言語：日本語   出版者・発行元：Procedia - Social and Behavioral Sciences  

This study investigates stochastic saturation flow rate in Japan starting from shared permissive left-turn lane. The methods used in Highway Capacity Manual 2000 and Japan Society of Traffic Engineering (JSTE) guideline were analyzed and evaluated. The comparison results show that both HCM and JSTE tend to overestimate the performed saturation flow rate in shared left-turn lane. As for detailed analysis, lane blockage probability is interpreted by using a binary logistic regression model. Then an empirical model is proposed to test the effect of lane blockage and significant influencing factors on saturation flow rate estimation in shared left-turn lane. © 2011 Published by Elsevier Ltd.

DOI： 10.1016/j.sbspro.2011.04.475

Web of Science

Scopus

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Quantifying the effects of signal timing and crosswalk geometry on pedestrian speed is an important requirement for improving existing operational policies and for providing a rational safety assessment at signalized intersections. The objective of this paper is to macroscopically investigate the effects of signal timing, crosswalk length and pedestrian origin-destination on pedestrian speed at signalized crosswalks. Three signalized crosswalks in Nagoya City are videotaped. A pre-developed data processing program is utilized to extract speed data. Pedestrian signal timing is divided into six intervals. Depending on the entering time, each pedestrian is assigned to one of the intervals. Then the speed distributions in different time interval are estimated and compared. Generally, it is concluded the entering speeds of pedestrians increase as pedestrian green interval proceeds. Moreover, pedestrians show higher travel speeds at long crosswalks.

DOI： 10.11175/eastpro.2011.0.105.0

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

This paper investigates urban expressway capacity characteristics of lane closure sections due to accidents. Methodology includes the following parts: 1) identification of a breakdown due to an accident, 2) estimation of capacity under accident conditions, 3) exploring features of capacity drop percentage, and 4) fitting probability distribution of capacity drop percentage. Accident record data and loop detector data on Odaka Route of Nagoya Expressway during three years are utilized to fulfill the investigation. The results reveal that mean capacity value increases and its variance turns to be convergent with increase of lane closure duration. Accident types like multiple rear-end collisions and rear-end collisions result in comparatively greater values of capacity drop percentage. Also accidents on curve segments bring relatively higher capacity drops compared with those on straight segments. Furthermore, capacity drop percentage is shown to be stochastic, and Beta distribution can well fit its probability distribution.

DOI： 10.11175/easts.9.1286

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

The signal change and clearance intervals, more specifically the all-red times, are often set longer than necessary in Japan. Too long all-red times not only increase lost time but also may induce aggressive pass and lead to safety drop. Hence, the objective of this study is to investigate the impacts of intersection geometry, signal control, and traffic conflicts on driver's start-up behavior during the signal change and clearance intervals. By using extensive field data, stochastic models are developed for estimating the distributions of starting response time (SRT) and acceleration rate of the entering vehicles. A numerical examination is performed to explore the possibility of reducing the length of all-red times when the aforementioned impacts on start-up behavior are incorporated into the calculation procedure. Conclusions support that the minimum required all-red times can be reduced by 1 second.

DOI： 10.11175/eastpro.2011.0.306.0

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

The number of pedestrian injuries and fatalities involved by left-turning vehicles (in left-hand traffic) at signalized intersections occupies a very large portion in traffic accidents. Installing channelization islands, e.g. raised islands or zebra marking islands at intersections is considered as one of the most important factors influencing on conflicts between pedestrians and left-turning vehicles. However, their impacts on vehicle maneuvers have not been quantitatively analyzed. The objective of this study, therefore, is to quantitatively evaluate the impacts of channelization islands, on maneuvers of left-turning vehicles. Results of the analyses on turning vehicle maneuvers conclude that the use of raised islands gives between one-and-a-half to two times greater impacts on the trajectory and the speeds as compared to the impacts of zebra islands. The use of zebra marking islands has low influence on the vehicle trajectory and the speed.

DOI： 10.11175/easts.9.1938

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Existing signal control strategies do not consider pedestrian flows in optimizing signal parameters, which may impose significant delays on pedestrians. This study aims to investigate the rationality and effectiveness of designing signal coordination for pedestrians. A Japanese numerical case study is analyzed. Field survey is conducted to collect the geometric characteristics, signal timings and vehicular traffic condition information. In a parallel approach, the performances of signal coordination for vehicular and pedestrian traffic are estimated by using the vehicular simulation tool Synchro/SimTraffic and the pedestrian simulation tool NOMAD. The results showed that the coordination for the major pedestrian flow led to a significant reduction in average delay (15%). Generally, it is concluded that the effectiveness of pedestrian signal coordination is not guaranteed but depends on the relationship between pedestrian platoon dispersion and the signal cycle length.

DOI： 10.11175/eastpro.2011.0.225.0

CiNii Research

記述言語：英語   出版者・発行元：公益社団法人 土木学会  

&nbsp;Evaluation of impacts of congestion improvement scheme s on travel time reliability is very significant for road authorities since travel time reliability repr esents operational performance of expressway segments. In this paper, a methodology is presented to estimate travel tim e reliability prior to implementation of congestion relief schemes based on travel time variation modeling as a function of demand, capacity, weather conditions and road accident s. For subject expressway segmen ts, traffic conditions are modeled over a whole year considering demand and capacity as random variables. Patterns of demand and capacity are generated for each five minute interval by appl ying Monte-Carlo simulation technique, and accidents are randomly generated based on a model that links acci dent rate to traffic conditions. A whole year analysis is performed by comparing de mand and available capacity for each scenario and queue length is estimated through shockwave analysis for each time in terval. Travel times are estimated from refined speed-flow relationships developed for intercity expressways and buffer time index is estimated consequently as a measure of travel time reliability. For validation, estimated reliability indices are compared with measured values from empirical data, and it is shown that the proposed method is suitable for operational evaluation and planning purposes.

DOI： 10.2208/jscejipm.67.283

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Although several safety countermeasures such as reforming intersection layouts have been implemented, methods to evaluate their effects prior to installation has not yet been established. One of the important safety issues at signalized intersections is the interaction between left-turning vehicles (left-hand traffic) and pedestrians/cyclists. This paper aims to analyze and model the trajectory variations of left-turning vehicles. Vehicle trajectories are collected at several signalized intersections with various traffic and geometric characteristics by video observations. The analysis reveals a significant variation in trajectories depending on intersection angle, number of exit lanes and vehicle type. For modeling individual vehicle trajectories and their distribution, the Euler-spiral-based approximation methodology is applied. Model validation showed that estimated trajectory distributions explain well the spatial maneuver of left-turning vehicles.

DOI： 10.11175/easts.9.1543

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Although several safety countermeasures such as reforming intersection layouts have been implemented, methods to evaluate their effects prior to installation has not yet been established. One of the important safety issues at signalized intersections is the interaction between left-turning vehicles (left-hand traffic) and pedestrians/cyclists. This paper aims to analyze and model the trajectory variations of left-turning vehicles. Vehicle trajectories are collected at several signalized intersections with various traffic and geometric characteristics by video observations. The analysis reveals a significant variation in trajectories depending on intersection angle, number of exit lanes and vehicle type. For modeling individual vehicle trajectories and their distribution, the Euler-spiral-based approximation methodology is applied. Model validation showed that estimated trajectory distributions explain well the spatial maneuver of left-turning vehicles.

DOI： 10.11175/eastpro.2011.0.309.0

CiNii Research

出版者・発行元：公益社団法人 土木学会  

2003年の道路構造令の改正により，往復分離2車線横断面が自動車専用道路(自専道)の構造として採用できることとなった．本構造は従来の多車線横断面に比べ建設コストの縮減が見込まれるものの，実現する速度性能は不明確であり，道路交通状況によっては求められる速度サービスが確保できない恐れもある．<br>　本論文では，2車線自専道の性能照査型計画設計を念頭に置き，車両感知器データ等を用いて交通量―速度関係(速度性能曲線)について分析する．まず，大型車混入率や降雨などの速度への影響要因を定量的に明らかにする．そして，それらの結果をもとに速度性能曲線を定式化し，これを用いた性能照査手法を提示する．これにより，速度性能の観点から2車線自専道構造の導入の可否や，更なるコスト縮減の可能性について検討することが可能となる．

DOI： 10.2208/jscejipm.67.261

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

我が国の駅前広場は，タクシーの客待ち行列による混雑やキスアンドライド車両の増加への対応など，円滑性・安全性に関する問題が顕著となっており，駅前空間が最優先すべき交通結節機能がうまく発揮されない状態にある．特にキスアンドライド車両は挙動特性が十分明らかになっておらず，設計時の施設の配置においても車両の停車特性への考慮が不十分である場合が多い．そこで本研究は，駅前広場構造や施設配置などがキスアンドライド車両の停車特性に与える影響を明らかにすることを目的とする．実データの分析に基づいて停車位置選択のモデル化を行い，送迎の目的別に選択影響要因の違いを示した．また，停車位置のシミュレーションを行い，障害物や施設配置による停車位置選択への影響を把握することができた．

DOI： 10.2208/jscejipm.67.67_i_1079

CiNii Research

出版者・発行元：公益社団法人 土木学会  

本論文では，往復2車線道路におけるサービスの質の評価指標として追従車密度を採用し，付加追越車線設置効果を評価する方法の開発を行う．そして，付加追越区間長とその設置間隔に応じて実現するサービスの質を定量的に求め，設計指針としての示唆を与えることを目的とする．交通流実態調査データに基づくシミュレーション実験によって得られた結果をモデル化することによって，付加追越区間長および片側1車線区間長と追従車密度の関係を定式化した．そして，付加追越車線の設置水準として，所要の性能目標を達成するための最短の区間長と最大の設置間隔の組合せを示した．さらにこの考え方を応用して，海外における典型的な2+1車線道路及び日本の2車線道路の付加追越車線の設置基準により実現すると考えられるサービスの質を評価した．

DOI： 10.2208/jscejipm.67.270

CiNii Research

出版者・発行元：公益社団法人 土木学会  

日本では，道路交通混雑は早くから大きな社会的・技術的問題となっており，とくに交通渋滞の緩和を目的とした道路の交通容量に関する実証的調査・研究が，実務・研究の双方において取り組まれている．また，性能照査型の道路計画設計を取り入れて行くに際しては，実現する交通運用状態を示すサービスの質を的確に把握することが鍵となる．本稿では，高速道路および一般道における特徴的なボトルネック現象について，これまで得られた知見を整理した上で，近年の日本における交通容量・サービスの質に関わる研究の状況や実務上の技術的な取り扱いを概観するとともに，これらの分野における今後の研究の方向性について展望する．

DOI： 10.2208/jscejipm.67.217

CiNii Research

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

日本の道路交通は，本来その道路に求められるはずのトラフィック機能やアクセス機能に対応した望ましい性能が十分発揮できるようには必ずしも計画・設計されているとはいえず，道路構造や交通運用の上で，多くの改善の余地が残されている．コストを抑え，かつその道路に必要な機能に応じた性能を十分に発揮させるよう，交通の質を改善可能なコスト・パフォーマンスの高い道路として改良を施し，再編していくことが必要である．これらに対処するためには，従来の手法では限界があり，機能に対応した性能を実現するために必要な道路構造と交通運用の組合せを柔軟に採用する，性能照査型道路計画設計手法の導入が必要だと考えられる．本稿では，「性能照査型道路計画設計」の特集にあたって，その考え方の概要と関連する技術的検討課題，ならびに特集号の構成について述べる．

DOI： 10.2208/jscejipm.67.195

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

In Japan, where vehicles travel on the left side of the road, the queue discharge rates of shared left-turn lane usually show comparable fluctuation, due to different departure characteristics of through and left-turning vehicles as well as interactions with pedestrians and bicycles. For a better evaluation of signalized intersections and then corridor performance, this study investigates stochastic queue discharge rates starting from shared left-turn lane and empirically explores its implications. Results show that efficient utilization of shared lane by through traffic can significantly improve discharge rate. At lower and higher pedestrian-bicycle volumes, discharge rates are relatively reliable. While at middle levels of pedestrian demands, more random arrivals and interactions lead to rather unstable saturation flow rate fluctuation. For the shared lane with a larger left turning radius, its discharge rates display a stable trend.

DOI： 10.11175/eastpro.2011.0.300.0

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

In Japan, where vehicles travel on the left side of the road, the queue discharge rates of shared left-turn lane usually show comparable fluctuation, due to different departure characteristics of through and left-turning vehicles as well as interactions with pedestrians and bicycles. For a better evaluation of signalized intersections and then corridor performance, this study investigates stochastic queue discharge rates starting from shared left-turn lane and empirically explores its implications. Results show that efficient utilization of shared lane by through traffic can significantly improve discharge rate. At lower and higher pedestrian-bicycle volumes, discharge rates are relatively reliable. While at middle levels of pedestrian demands, more random arrivals and interactions between pedestrians and vehicles lead to rather unstable saturation flow rate fluctuation. For the shared lane with a larger left turning radius, its discharge rates display a stable trend. A comparative analysis between observed saturation flow rates, Highway Capacity Manual (HCM, 2000) and Japanese guideline (JSTE, 2007) estimations indicate both HCM and Japanese guideline usually overestimate the discharge rates in shared left-turn lane in Japan.

DOI： 10.11175/easts.9.1499

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

The number of pedestrian injuries and fatalities involved by left-turning vehicles (in left-hand traffic) at signalized intersections occupies a very large portion in traffic accidents. Installing channelization islands, e.g. raised islands or zebra marking islands atintersections is considered as one of the most important factors influencing on conflicts between pedestrians and left-turning vehicles. However, their impacts on vehicle maneuver have not been quantitatively analyzed. The objective of this study, therefore, is to quantitatively evaluate the impacts of channelization islands, on maneuvers of left-turning vehicles. Results of the analyses on turning vehicle maneuvers conclude that the use of raised island gives between one-and-a-half to two times greater impacts on the trajectory and the speeds as compared to the impacts of zebra islands. The use of zebra marking islands has low influence on the vehicle trajectory and the speed.

DOI： 10.11175/eastpro.2011.0.380.0

CiNii Research

出版者・発行元：IATSS Research  

Among various pedestrian facilities, signalized crosswalks are the most complex and critical ones. Their geometry and configuration including width, position and angle directly affect the safety, cycle length and resulting delays for all users. Existing manuals do not provide clear and rational specifications for the required crosswalk width under different pedestrian demand combinations and properties. Furthermore, they do not consider the bi-directional flow effects on crossing speed and time when addressing pedestrian flow at signalized crosswalks. However, quantifying the effects of such interactions on the behavior of pedestrian flow is a prerequisite for improving the geometric design and configuration of signalized crosswalks. The objective of this paper is to develop a methodology for estimating the required crosswalk width at different pedestrian demand combinations and a pre-defined LOS. The developed methodology is based on theoretical modeling for total pedestrian platoon crossing time, which consists of discharge and crossing times. The developed models are utilized to generate the fundamental diagrams of pedestrian flow at signalized crosswalks. A comprehensive discussion about the effects of bi-directional flow and various pedestrian age groups on the characteristics of pedestrian flow and the capacity of signalized crosswalks is presented. It is found that the maximum reduction in the capacity of signalized crosswalks occurs at roughly equal pedestrian flows from both sides of the crosswalk. By utilizing existing LOS thresholds for pedestrian flow at signalized crosswalks, the required crosswalk widths for various pedestrian demand combinations are proposed for implementation. © 2010 International Association of Traffic and Safety Sciences.

DOI： 10.1016/j.iatssr.2010.06.002

Scopus

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Existing manuals do not provide clear specifications for the required crosswalk width under different pedestrian demand volumes and characteristics. However, optimizing crosswalk configurations including width is an important concern to improve the overall performance of signalized intersections. The objective of this paper is to develop a methodology for estimating minimum required crosswalk width at different pedestrian demand volumes considering bi-directional flow and different pedestrian age groups. The developed methodology is based on modeling total pedestrian platoon crossing time which consists of discharge and crossing times. Discharge time is modeled by using shockwave theory while crossing time is modeled by applying aerodynamic drag theory. The developed models are then calibrated for crosswalks with mainly elderly or pupil pedestrian platoons. A set of criteria based on pedestrian crossing speed is developed to identify the minimum required crosswalk width. Finally, different required crosswalk widths are proposed for different pedestrian demand volumes and directional split ratios considering the effects of pupil and elderly pedestrian platoons.

DOI： 10.11175/eastsats.1.181

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

For a follower-based service measure to be effectively used for two-lane highway quality of service evaluation, a more reliable follower identification procedure is necessary. Current follower recognition methodologies are based on single critical headway values that may not accurately identify followers since they do not take into account the randomness of preferred tracking headways and drivers' desired speeds. This paper presents an improved, probability-based follower identification methodology that takes both of these factors into account while also considering their variability across different driving conditions. The calculated follower percentage and follower density values were compared with those estimated using the 3-second threshold suggested by the HCM. The proposed methodology estimated more followers, particularly during periods of heavy flow, highlighting the inability of using a single headway value to correctly identify followers. The resulting follower counts have been normalized, making it possible to theoretically identify followers at any given time or driving condition.

DOI： 10.11175/easts.8.1822

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   出版者・発行元：Transportation Research Record  

This study presents a probabilistic safety estimation approach based on traffic conflict technique. The study aims to investigate the impacts of the German signal control policy and intergreen design method on safety during intergreen intervals at signalized intersections in Japan. To facilitate application of the policy, the uncertainty of input variables and of safety itself, indicated by the postencroachment time, was analyzed first by means of field data collected at 12 typical intersections in Japan and Germany. A few case studies were then examined with Monte Carlo simulation. The results indicated that safety during the intergreen interval and its reliability might significantly drop if intergreen times were simply changed from the values based on the Japanese method to the values based on the German method without supplementary countermeasures. However, safety as well as reliability can be maintained if the Japanese control policy is completely replaced with the German one.

DOI： 10.3141/2128-23

Web of Science

Scopus

記述言語：日本語   出版者・発行元：Transportation Research Record  

Preevaluation of the impacts of congestion relief schemes on travel time reliability is significant for road authorities. However, most existing approaches to estimating travel time reliability rely mainly on empirical data and are therefore not of help for evaluating improvement schemes before implementation. A methodology is presented to estimate travel time reliability on the basis of modeling travel time variations as a function of demand, capacity, weather conditions, and road accidents. For a subject expressway segment, patterns of demand and capacity were generated for each 5-min interval during a year by using the Monte Carlo simulation technique, and accidents were generated randomly according to traffic conditions. A whole year analysis was performed by comparing demand and available capacity for each scenario; shock wave analysis was used to estimate the queue length at each time interval. Travel times were estimated from refined speed-flow relationships. The buffer time index was estimated as a measure of travel time reliability and compared with observed values from empirical data. After validation, the methodology was applied to assess the impact on travel time reliability of opening the hard shoulder to traffic. Opening the hard shoulder to traffic during the peak periods was found to ameliorate travel time reliability significantly and mitigate congestion levels, which could result in up to a 26% cut in the number of accidents occurring.

DOI： 10.3141/2124-13

Web of Science

Scopus

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Current follower recognition methodologies are based on single critical headway values that may not accurately identify followers since they do not take into account the randomness of preferred tracking headways and drivers desired speeds. This paper presents an improved, probability-based follower identification methodology that takes both of these factors into account while also considering their variability across different driving conditions. The calculated follower percentage and follower density values were compared with those estimated using the 3-second threshold suggested by the HCM. The proposed methodology estimated more followers, particularly during periods of heavy flow, highlighting the inability of using a single headway value to correctly identify followers. The resulting follower counts have been normalized, making it possible to theoretically identify followers at any given time or driving condition.

DOI： 10.11175/eastpro.2009.0.338.0

CiNii Research

出版者・発行元：16th ITS World Congress  

This paper presents the evaluation results on operational and safety performance of group-based signal control, based on a field test undertaken in Japan recently. Starting response time (SRT), start-up lost time (SULT), clearance lost time (CLT), saturation flow rate (SFR), and approach delay (AD) are selected to represent operational performance. Certain occurrence frequencies and rates of stop-line crossing during amber (SCA) and red-light-running (RLR) act as the measures to safety performance during intergreen intervals. The results from the before-and-after analyses supported that the group-based control itself generally didn't significantly affect SRT, SULT, CLT, and SFR, while remarkably improved AD. Meanwhile, it substantially decreased SCA and RLR at the exclusive through and right-turn lanes. It reveals that both operational and safety benefits might be expected by applying such a policy.

Scopus

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

Existing manuals do not provide clear specifications for the required crosswalk width under different pedestrian demands and properties. However, optimizing crosswalk configurations including width is an important concern to improve the overall performance of signalized intersections. The objective of this paper is to develop a methodology for estimating minimum required crosswalk width at different pedestrian demands considering bi-directional flow and different pedestrian age groups. The developed methodology is based on modeling total pedestrian platoon crossing time which consists of discharge and crossing times. Discharge and crossing times are modeled by using shockwave and aerodynamic drag theories respectively. Then developed models are calibrated for crosswalks with elderly or pupil pedestrian platoons. A criteria based on pedestrian crossing speed is developed to identify the minimum required crosswalk width. Finally, different minimum required crosswalk widths are proposed.

DOI： 10.11175/eastpro.2009.0.222.0

CiNii Research

出版者・発行元：Proceedings of the 7th International Conference of Chinese Transportation Professionals Congress 2007: Plan, Build, and Manage Transportation Infrastructures in China  

An official nationwide manual on intersection planning and design remains absent in China. Presently, a research group led by Tongji University is addressing its first version. Toward gaining more profound knowledge on state of the art in intersection design and operations in overseas while developing Chinese manual, this paper thus presents German and Japanese experiences. Conclusions, future studies and efforts essential for China are discussed finally. © 2008 ASCE.

DOI： 10.1061/40952(317)51

Scopus

記述言語：英語  

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語  

記述言語：日本語   出版者・発行元：Transport Reviews  

In transport terms, Japan has an enviable reputation for operating effectively an incredibly complex road and rail system. However, relatively little is known about how this is done or about the issues that are facing policy-makers and shapers in the country. The purpose of this paper, then, is to investigate how land passenger transport is organized in Japan, and to begin to evaluate its effectiveness. This is done by drawing on a literature review and on findings from a scoping study based on a series of semi-structured in-depth interviews with key practitioners. Overall, the findings suggest that national and local transport policy in Japan faces a number of key challenges across all modes in the land passenger transport system, in particular relating to the fragmented approach to policy development, implementation, and operation and to the growing role of the car.

DOI： 10.1080/01441640701526699

Web of Science

Scopus

記述言語：日本語   出版者・発行元：Transportation Research Record  

On a two-lane highway with passing restrictions, user dissatisfaction usually is caused by the inability to drive at the desired speed because of a relatively slower lead vehicle. Although this condition clearly shows that vehicles in this state are following, current definitions of "following vehicle" are based mainly on headway alone. A "follower" can be more logically defined as a vehicle traveling below its desired speed because of the presence of a relatively slower lead vehicle. The problem arises because the desired speeds of different drivers vary significantly; the variation makes it difficult to assess whether a vehicle is constrained on the basis of directly accessible data alone. A study was done to develop desired speed distributions for various traffic, weather, and ambient conditions, which can be later used as input for simulation or to calculate a vehicle's following probability given its current speed. The collected data were classified according to different traffic, geometric, weather, and ambient conditions to form 64 data sets for analysis. The desired speed distributions were estimated by using the modified Kaplan-Meier approach and were found to be suitable for use as either simulation input or as a tool that can be used for follower identification. Differences between holiday and weekday travel speed preferences and effects of weather on driver speed choices were also found.

DOI： 10.3141/2088-23

Web of Science

Scopus

出版者・発行元：公益社団法人 土木学会  

我が国の道路は, 実現する交通性能を十分照査することなく過去に定められた仕様に基づき計画設計されている. 今まで以上にコスト・パフォーマンスの高い道路が求められる現在, 筆者らは仕様型ではなく性能照査型の道路計画設計の必要性を提唱している. 本論文では, 時間交通需要の変動を考慮し計画設計道路の交通性能を推計する手法を構築し, これを用いた性能照査型の道路計画設計法を提案した. これにより, その道路の機能に応じて求められる性能を確認し道路を計画設計することができる. また予算, 空間等の制約条件の下で, 代替案を比較検討することができ, 合理的な道路構造と交通運用の組合せを選択することも可能となる.

DOI： 10.2208/journalip.25.67

CiNii Research

出版者・発行元：IATSS Research  

Unlike the typical stage-based policy commonly applied in Japan, the group-based control (often called movement-based in the traffic control industry in Japan) refers to such a control pattern that the controller is capable of separately allocating time to each signal group instead of stage based on traffic demand. In order to investigate its applicability at signalized intersections in Japan, an intersection located in Yokkaichi City of Mie Prefecture was selected as an experimental application site by the Japan Universal Traffic Management Society (UTMS). Based on the data collected at the intersection before and after implementing the group-based control policy respectively, this study evaluated the impacts of such a policy on driver behavior and intersection safety. To specify those impacts, a few models utilizing cycle-based data were first developed to interpret the occurrence probability and rate of red-light-running (RLR). Furthermore, analyses were performed on the yellow-entry time (Ye) of the last cleared vehicle and post encroachment time (PET) during the phase switching. Conclusions supported that the group-based control policy, along with certain other factors, directly or indirectly influenced the RLR behavior of through and right-turn traffics. Meanwhile, it has potential safety benefits as well, indicated by the declined Ye and increased PET values. © 2008 International Association of Traffic and Safety Sciences.

DOI： 10.1016/S0386-1112(14)60211-9

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語  

記述言語：英語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語  

記述言語：英語  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   出版者・発行元：Transportation Research Record  

This paper aims to investigate the breakdown phenomenon at on-ramp merging sections of urban expressways in Japan. The breakdown events are treated here as a probabilistic phenomenon. Six merging sections at which breakdowns frequently occur are selected to be different in their geometry in relation to acceleration lane length and ramp entrance side. Three different aspects of merging capacity are recognized: the maximum outflow rate before the breakdown, the outflow rate when the breakdown starts to occur, and the outflow rates during the queue discharge period. These outflow aspects are analyzed after they are converted into an equivalent passenger car unit to eliminate the effect of heavy vehicles. Then the probability of breakdown at these sections is investigated as a function of outflow rates. The observed breakdown probabilities follow the Weibull distribution function at all sections, with close values of shape parameter and wide range values of scale parameter. The values of the scale parameter are used to investigate the effects of the acceleration lane length and entrance ramp side. Moreover, the breakdown probability is investigated as a function of the occupancy observed immediately downstream of the merging section. Last, the effects of ramp flow ratio and interval length of aggregated data are discussed.

DOI： 10.3141/2012-02

Web of Science

Scopus

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

The authors are currently investigating the applicability of the operation policy, commonly applied at signalized intersections in Germany, for Japanese signalized intersections. As an initial step, this study analyzed traffic characteristics and driver behavior at several typical German and Japanese intersections to understand the impacts of such policy on them. The results showed that German intersections had significantly lower starting response time (SRT) and start-up lost time (SULT), which was due to the sequence of signal indications. However, no apparent variations existed in saturation flow rate (SFR) and lost time in amber (LTA). Left turners at German intersections tended to be more aggressive in choosing suitable gaps, indicated by critical gap and 1/PET values. Moreover, longer all-red clearance interval and gap adaptive control seemed to encourage aggressive pass. Lower stop-line crossing during amber (SCA) and red light violation (RLV) rates at German intersections were attributed to multiple factors.

DOI： 10.11175/eastpro.2007.0.324.0

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

The authors have advocated a new planning and design methodology in for highways in Japan, which includes operational performance check in consideration of the traffic demand fluctuation. For this method, it is necessary to reproduce the hourly traffic demand fluctuation on a planned and designed highway section throughout a year. This study proposes a method to reproduce it with two phases; reproducing the daily traffic demand phase and setting the hourly traffic demand coefficient phase, in consideration of potential hourly traffic demand on a day with congestion. The reproduced hourly traffic demand fluctuation using this method was validated on two expressway sections in Japan. As a result, we could verify that the reproduction precision was satisfactory except that it could not consider some special local characteristics.

DOI： 10.11175/eastpro.2007.0.277.0

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

A roundabout is an alternative type of junction control that reduces delay under low traffic demand. Conditions under which they are advantageous in terms of capacity and delay have been already shown in existing researches. However, the implementation of roundabouts is likely to be negatively evaluated, particularly in Japan; due to safety reasons since traffic conflicts are inevitable when merging. In this paper, a methodology for the performance evaluation of at-grade junctions considering a trading-off relationship between delay and vehicular conflicts is proposed. The performance of signalized intersections and roundabouts are also compared by applying this methodology. As a result, it was found that roundabouts are still more advantageous than signalized intersections when approaching traffic volume is less than 500 vph, even though not only delay but also conflicts were taken into account as evaluation indices.

DOI： 10.11175/easts.7.2412

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

This paper introduces some applications of travel time based performance measures and mainly the travel time reliability as a measure of performance. In this research, operational conditions of two different segments of an intercity expressway are evaluated and compared by using travel time based performance measures. While Buffer Time Index and Travel Time Index are used to evaluate travel time reliability and congestion, it is observed that travel times are more reliable during off-peak periods, whereas unreliability dramatically increases during the peak periods. Additionally, travel time reliability varies from time to time according to demand fluctuations and traffic influencing events. Finally, highway segments are found to be more susceptible to disruptions caused by traffic influencing events once congestion starts to build up.

DOI： 10.11175/eastpro.2007.0.318.0

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

The effects of heavy vehicles become more pronounced in two-lane highway facilities with passing restrictions since vehicles in a platoon do not have any other choice but to follow the leaders&rsquo; choice of speed, which is usually below their desired speed levels. Furthermore, platoon lengths are expected to be longer than usual, affecting level of service indicators such as follower density and average travel speed. This study aims to make a preliminary analysis of the influence of heavy vehicle on such facility types in Japan. Detector data were analyzed for two different time periods &mdash; peak and weekday. The speed of heavy vehicles has a direct effect on follower speed and follower density was found to become more sensitive to heavy vehicle percentage as flow rate increases. Average speed was also found to be more sensitive to heavy vehicle presence on upgrades, especially during the evening period.

DOI： 10.11175/easts.7.2533

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

The effects of heavy vehicles become more pronounced in two-lane highway facilities with passing restrictions since vehicles in a platoon do not have any other choice but to follow the leaders' choice of speed, which is usually below their desired speed levels. Furthermore, platoon lengths are expected to be longer than usual, affecting level of service indicators such as follower density and average travel speed. This study aims to make a preliminary analysis of the influence of heavy vehicle on such facility types in Japan. Detector data were analyzed for two different time periods - peak and weekday. The speed of heavy vehicles has a direct effect on follower speed and follower density was found to become more sensitive to heavy vehicle percentage as flow rate increases. Average speed was also found to be more sensitive to heavy vehicle presence on upgrades, especially during the evening period.

DOI： 10.11175/eastpro.2007.0.330.0

CiNii Research

記述言語：英語   出版者・発行元：Eastern Asia Society for Transportation Studies  

The authors are currently investigating the applicability of the operation policy, commonly applied at signalized intersections in Germany, for Japanese signalized intersections. As an initial step, this study analyzed traffic characteristics and driver behavior at several typical German and Japanese intersections to understand the impacts of such policy on them. The results showed that German intersections had significantly lower starting response time (SRT) and start-up lost time (SULT), which was due to the sequence of signal indications. However, no apparent variations existed in saturation flow rate (SFR) and lost time in amber (LTA). Left turners at German intersections tended to be more aggressive in choosing suitable gaps, indicated by critical gap and 1/PET values. Moreover, longer all-red clearance interval and gap adaptive control seemed to encourage aggressive pass. Lower stop-line crossing during amber (SCA) and red light violation (RLV) rates at German intersections were attributed to multiple factors.

DOI： 10.11175/easts.7.2470

CiNii Research

出版者・発行元：公益社団法人 土木学会  

筆者らは, 性能照査型道路計画設計手法の導入を提案しているが, 計画/設計道路の性能をより的確に評価するためには, 年間8,760時間の時系列的な時間交通需要変動を考慮することが必要である. そこで本論文では, 日ベースと時間ベースの2段階に分け年間の時間交通需要変動を推計する手法を構築した. これにより車両感知器では直接観測することが困難な超過需要を考慮することができる. そして, この手法を用いて道路カテゴリ別の平均的な時間交通需要変動を推計した. これと各種条件・道路構造別の道路交通性能を組み合わせれば, 計画/設計道路で実現される交通状況を年間を通じて想定することができ, 道路の性能をより詳細に評価することが可能となる.

DOI： 10.2208/journalip.24.825

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

記述言語：英語  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

記述言語：英語  

記述言語：英語  

担当区分：筆頭著者   記述言語：英語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語  

CiNii Research

記述言語：日本語   出版者・発行元：国際交通安全学会  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語  

記述言語：日本語   出版者・発行元：Transportation Research Record  

Two-lane expressways exist as provisional sections for future expansion to four-lane expressways in Japan, although recently such roadway types have been considered for construction for permanent use. Their highway classification may fall somewhere between common (multilane) expressways and ordinary two-lane highways, with full access control and high speed limits but with only one lane per direction of travel. Since this type of highway is unique, methodologies for service level measurement of other uninterrupted-flow facilities are not applicable. Percent time spent following, for instance, is estimated with significant consideration of the opposing flow rate, which has practically no effect on driving conditions since a median barrier is present in all sections. The goal of this study is to analyze and compare possible performance measures that would best describe the traffic operational characteristics of two-lane expressways. Among the performance measures considered, follower density had much promise, having shown strong relationships with flow rate. Since the available data were only those taken during off-peak periods, further observations of follower flow must be made during congested or near-congested flow to establish follower density and volume relationships for all traffic conditions.

DOI： 10.3141/1988-16

Web of Science

Scopus

記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

交通工学分野においてビデオ画像観測は，車両などの詳細な挙動分析や交通状況の正確な把握に必須の観測手法であるが，車両走行軌跡のような詳細データをマニュアルで収集する場合，解析に膨大な時間と労力を要することが大きな課題であった．本研究では，画像処理技術を駆使することにより交通工学分野で多用される交通量計測，移動体追跡，車番認識を自動化し，データ収集作業の飛躍的な効率化を可能とする多機能ビデオ画像処理システムTrafficAnalyzerを開発した．本システムの性能を実際の家庭用デジタルビデオカメラ映像により検証した結果，交通量計測は概ね95％以上，車番認識は50％以上の認識性能を有し，移動体追跡では車両や歩行者などの詳細な挙動を1/10secごとに効率的に追跡できることを示した．

DOI： 10.2208/jscejd.62.276

CiNii Research

出版者・発行元：13th World Congress on Intelligent Transport Systems and Services  

This paper presents the overview of an integrated video image processing system which can count traffic volumes, track moving objects such as vehicles and pedestrians, and recognize license plates number automatically by using image processing technology without any special hardware. Case studies are carried out by applying this system to the actual road traffic scene, and its performance and accuracy are evaluated. Experimental results of the image processing show that each analysis function has sufficiently satisfactory performance for practical use.

Scopus

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CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語  

記述言語：英語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語  

CiNii Research

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語  

CiNii Research

記述言語：日本語   出版者・発行元：土木学会  

出版者・発行元：公益社団法人 土木学会  

DOI： 10.2208/jscej.2004.772_1

CiNii Research

記述言語：英語  

記述言語：英語  

担当区分：筆頭著者   記述言語：英語  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

記述言語：英語  

記述言語：英語  

担当区分：筆頭著者   記述言語：英語  

出版者・発行元：Proceedings of the International Conference on Applications of Advanced Technologies in Transportation Engineering  

This study aims to analyze the mechanism of risky behavior at inter-green periods and to develop a "behavior risk estimation model" which reflects driver's perception for evaluating cycle length under under-saturated traffic conditions. The risky behaviors at the inter-green period are expressed by a disaggregate logit model for each movement (through, right-rum, left-turn) using field survey data. These models are explained by delay and various traffic conflicts, which are influenced by cycle lengths. The estimated parameters of these models quantitatively indicate that longer cycle length induces more risky behaviors at inter-green periods.

DOI： 10.1061/40730(144)39

Scopus

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語  

担当区分：筆頭著者   記述言語：日本語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語  

担当区分：筆頭著者   記述言語：日本語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：英語  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語  

記述言語：日本語  

Web of Science

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

出版者・発行元：公益社団法人 土木学会  

都市部におけるP&R戦略の立案に際しては, P&R駐車場の規模や配置, 駐車料金などの施策導入条件に応じたP&R需要を的確に推定し, かつそれらが周辺交通流にもたらす影響を評価することが必要である. 本論文では, 端末アクセス交通手段選択を含んだ交通手段選択モデルを構築して各種P&R関連施策に伴う幹線・端末交通需要の変化を表現するとともに, それに応じた交通流への影響を時間的・空間的に評価するために微視的交通流シミュレーションを開発した. これらを組合せ, さらにDP&Rモデルを加えることで, 出発地から目的地までのインターモーダルトリップと交通状況のシミュレートが可能なP&R施策評価システムを構築した. また, 本システムを名古屋東部地域に適用し, 駐車場整備や情報提供などP&R関連施策の効果について考察した.

DOI： 10.2208/journalip.18.795

CiNii Research

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

出版者・発行元：公益社団法人 土木学会  

本研究は, 道路交通のサービスの質の1つの側面として, ドライバーの主観的快適性を表す満足度に基づいた定量化を試みるとともに, 満足度とそれを構成する印象, および交通状況との対応関係を明らかにすることを目的とする. 都市間高速道路の単路部を対象とした走行実験を実施し, 交通状況とドライバーの感覚に関するデータを収集し分析を行ったところ, 交通状況とドライバーの満足度, 運転挙動との間の対応関係を定量的に明示することができた. さらに, 満足度に基づくサービスの質の基準を仮定し, 既往の基準値と比較考察を行ったところ, 現在日本の高速道路の計画段階に想定している交通状況に対して, ドライバーは満足していない傾向にあることが示された.

DOI： 10.2208/journalip.17.941

CiNii Research

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   出版者・発行元：土木学会  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語  

出版者・発行元：公益社団法人 土木学会  

本論文は, TTS技術による情報提供のインターモーダル分野への適用例であるDynamic Park and Ride (DP&R) 施策を対象に, その導入効果の予測評価を試みたものである. 名古屋市東部地域において収集したSPデータを用いて, DP&Rシステム導入に伴うDP&R選択行動をモデル化するとともに, この選択モデルを組み込んだ簡便な交通シミュレーションを行った.その結果, DP&Rの実施が自動車走行距離やCO<SUB>2</SUB>排出の削減に寄与するためには, P&R駅における乗換抵抗や料金水準といったサービスの改善を同時に施す必要があることが定量的に示された.

DOI： 10.2208/journalip.16.949

CiNii Research

出版者・発行元：公益社団法人 土木学会  

道路の横断面構成は, 建設・維持管理費用や走行・時間費用はもとより, エネルギー消費・環境負荷にも大きく影響を及ぼすが, その決定に際して重要な役割を果たすのがサービス水準の設定である.本研究では, 高速道路単路部における横断面構成をライフサイクルにわたる費用 (Life Cycle Cost;LCC) の観点から評価することにより, サービス水準の設定を試みる. まず, 横断面構成, 地形・地域条件, AADTを入力条件とするLCCの推計手法を構築する. 次に, これらが最小となる横断面代替案において実現されるサービス水準を, 交通量-交通容量比 (<I>v/c</I>) で定量的に表現する. その結果, 規格の高い道路ほどLCCが小さくなる傾向や, 現行のサービス水準はLCC最小基準と拡張ライフサイクルCO<SUB>2</SUB>最小基準による最適値の概ね中間に位置することが示される.

DOI： 10.2208/journalip.16.933

CiNii Research

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

出版者・発行元：公益社団法人 土木学会  

我が国の運輸交通部門からのCO2排出量を, どの規模の都市でどの程度削減する必要があり, またそのために求められる施策の程度がどのくらいかといった具体的な数値目標が明示されていない. CO2排出量削減を確実に達成するためには, 具体的な目標設定の上で, 交通施策を決断し努力する必要がある. 本研究では, 2010年におけるCO2排出量の必要削減量を設定し, その実現に向けて必要な交通施策目標値を提示する. 特に都市内旅客輸送に関しては, 交通機関分担率や輸送効率をはじめとした交通特性が都市の規模により異なることを考慮して, 必要なCO2排出削減量, およびそのための交通施策目標値を都市規模別に算出し, 実現可能性について考察する.

DOI： 10.2208/journalip.15.739

CiNii Research

出版者・発行元：公益社団法人 土木学会  

This paper proposes a method for the comprehensive assessment on cross-sectional structures of inter-city motorways in terms of CO<SUB>2</SUB> emission. The index employed in this study is the &ldquo;Extended Life-cycle CO<SUB>2</SUB> (ELC-CO<SUB>2</SUB>)&rdquo; emission from highways. This takes into account of not only the CO<SUB>2</SUB> generated by highway construction and maintenance works, but also the CO<SUB>2</SUB> emission by traffic, which varies by highway cross-sectional design. Such traffic flow characteristics as traffic flow variations and/or speed-flow relationship is also investigated, which has not been considered in the conventional studies on LCA. The CO<SUB>2</SUB> emission by highway construction and maintenance works is estimated using &ldquo;combined method&rdquo;, for elevated, mounded, and tunnel sections respectively. Furthermore, various cross-sectional structures by several geographical and land-use conditions are assessed, through the calculation of ELC-CO<SUB>2</SUB> from each alternative.

DOI： 10.2208/proer1988.26.261

CiNii Research

出版者・発行元：公益社団法人 土木学会  

CO<SUB>2</SUB> emission from transport sector is drastically increasing, and this trend will never change without any appropriate countermeasures against that. Policies relating to reduction of CO<SUB>2</SUB> emission from transport sector are categorized by 1) stage in environmental influence mechanism, and 2) their method. On the other hand, a target value of CO<SUB>2</SUB> emission from Japanese urban passenger transport in 2010 is assumed to be the same level as that in 1990. Its value is estimated by population size of city, considering differences of transport properties and its effects on CO<SUB>2</SUB> reduction. Furthermore, required amount of each policy option for achieving the target value is calculated. Consequently, it is found that 1) no single policy option is effective, even if vehicle fuel consumption efficiency would be drastically improved, that results in necessity of combining various policy options, 2) effective measures in small cities is essential, whose transport activities are strongly dependent on automobiles and that cause about 80% of total CO<SUB>2</SUB> emission from urban passenger transport.

DOI： 10.2208/proge.6.121

CiNii Research

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（学術雑誌）  

記述言語：日本語  

記述言語：日本語   掲載種別：研究論文（学術雑誌）