研究者詳細 - 中村　英樹

Methodology to Evaluate the Quality of Service of Traffic Flow on Intercity Expressway Sections by using Follower Percentage

Konda, H; Nakamura, H

TRANSPORTATION RESEARCH RECORD 2674 巻 ( 6 ) 頁： 200 - 210 2020年6月

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

Introducing a multi-variate classification method: Risky driving acceptance among different heterogeneous driver sub-cultures

Timmermans, CPM; Alhajyaseen, WKM; Ross, V; Nakamura, H

JOURNAL OF SAFETY RESEARCH 73 巻頁： 81 - 91 2020年6月

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

Modeling the Impact of Downstream Conditions on Discharging Behavior of Vehicles at Signalized Intersections Using Micro-Simulation

PubMed

Zhu, H; Nakamura, H; Alhajyaseen, W

ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 45 巻 ( 5 ) 頁： 4187 - 4202 2020年5月

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

Modeling Traffic Flows on Urban Arterials Considering the Downstream Influence

Zhu, H; Nakamura, H; Alhajyaseen, W; Iryo-Asano, M

TRANSPORTATION RESEARCH RECORD 2674 巻 ( 5 ) 頁： 475 - 485 2020年5月

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

高速道路における追従状態を考慮した交通流のサービスの質に関する評価指標の検討査読有り

近田博之, 中村英樹

交通工学論文集 6 巻 ( 2 ) 頁： A_9 - A_15 2020年2月

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

<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>

DOI： 10.14954/jste.6.2_a_9

信号交差点密度を考慮した Q-V 関係式が道路事業便益推定に与える影響査読有り

柿元祐史, 中村英樹

交通工学論文集 6 巻 ( 2 ) 頁： A_198 - A_205 2020年2月

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

<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>

DOI： 10.14954/jste.6.2_a_198

A Study on using Free Speed for Estimating Expressway Quality of Service 査読有り

AKANDWANAHO Edwin, NAKAMURA Hideki

交通工学論文集 6 巻 ( 2 ) 頁： A_244 - A_253 2020年2月

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

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, FSI = AS/FS as an indicator of expressway QOS perception. FSI was found to decrease with an increase in traffic flow, and its potential applications are discussed.

DOI： 10.14954/jste.6.2_a_244

追従車構成率を用いた都市間高速道路の交通流のサービスの質の評価査読有り

近田博之・中村英樹

高速道路と自動車 63 巻 ( 2 ) 頁： 22 - 29 2020年2月

Analysis of Travel Speed on 4-Lane Signalized Arterials Open Access

Akandwanaho E., Nakamura H.

Transportation Research Procedia 48 巻頁： 890 - 903 2020年

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

Open Access

Traffic safety culture of professional drivers in the State of Qatar Open Access

Timmermans C., Alhajyaseen W., Reinolsmann N., Nakamura H., Suzuki K.

IATSS Research 43 巻 ( 4 ) 頁： 286 - 296 2019年12月

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

Open Access

自動運転車両の混在が信号交差点交通容量に与える影響に関する分析

Study on Start-up Lost Time at Signalized Intersections Considering Downstream Conditions 査読有り

Zhu, H. and Nakamura, H.

75 巻 ( 5 ) 頁： I_1121 - I_1130 2019年12月

Estimation of Roundabout Entry Capacity and Passenger Car Equivalent for Heavy Vehicles Considering the Impact of Geometric Elements 査読有り

Fang, Y., Zhang, X. and Nakamura, H.

Journal of JSCE D3 75 巻 ( 5 ) 頁： I_1167 - I_1176 2019年12月

ラウンドアバウト幾何構造の安全性能評価のためのリスク指標モデリング査読有り

吉岡慶祐・中村英樹・下川澄雄・森田綽之

土木学会論文集D3 75 巻 ( 3 ) 頁： 191 - 201 2019年10月

鰐部万磨, 柿元祐史, 中村英樹, 井料美帆

交通工学論文集 5 巻 ( 2 ) 頁： A_167 - A175 2019年2月

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>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>

DOI： 10.14954/jste.5.2_a_167

ESTIMATION OF ROUNDABOUT ENTRY CAPACITY AND PASSENGER CAR EQUIVALENT FOR HEAVY VEHICLES CONSIDERING THE IMPACT OF GEOMETRIC ELEMENTS

Introduction

Tang K.

Global Practices on Road Traffic Signal Control: Fixed-Time Control at Isolated Intersections 頁： 1 - 5 2019年1月

FANG Yao, ZHANG Xin, NAKAMURA Hideki

土木学会論文集D3（土木計画学） 75 巻 ( 5 ) 頁： I_1167 - I_1176 2019年

記述言語：英語出版者・発行元：公益社団法人土木学会

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.

DOI： 10.2208/jscejipm.75.i_1167

ラウンドアバウト幾何構造の安全性能評価のためのリスク指標モデリング

吉岡慶祐, 中村英樹, 下川澄雄, 森田綽之

土木学会論文集D3（土木計画学） 75 巻 ( 3 ) 頁： 191 - 201 2019年

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．

DOI： 10.2208/jscejipm.75.191

STUDY ON START-UP LOST TIME AT SIGNALIZED INTERSECTIONS CONSIDERING DOWNSTREAM CONDITIONS

ZHU Hong, NAKAMURA Hideki

土木学会論文集D3（土木計画学） 75 巻 ( 5 ) 頁： I_1121 - I_1130 2019年

記述言語：英語出版者・発行元：公益社団法人土木学会

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.

DOI： 10.2208/jscejipm.75.i_1121