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

Older drivers who are aware of their declining functions tend to adopt a cautious driving style to compensate for their declining driving abilities. However, whether cautious older drivers are associated with a reduced crash risk has not been well studied. In this study, we examined the association between older drivers’ cautious driving style and crash risk using a novel driving style recognition method. We proposed a driving style recognition method that does not require predefined thresholds and applied it to the driving data of 71 drivers comprising 59 drivers aged 65 years or older (mean age 72.4; 67.8 % male) and 12 drivers aged 51–64 years (mean age 58.3; 66.7 % male). Drivers were classified into cautious and relatively aggressive groups based on the classification results of their speed, acceleration, and braking styles. The results showed that cautious drivers were characterized by older age, poorer Trail Making Test Part B performance, less frequent night driving, and lower driving exposure, indicating that older drivers may adopt multiple compensatory strategies. Although the crash involvement rate of cautious older drivers was approximately half that of relatively aggressive drivers, the difference was not statistically significant. Furthermore, this difference was expected to decrease when driving exposure was considered. Older drivers who adopted a cautious driving style but were involved in traffic crashes had poorer visual acuity and contrast sensitivity. The results of this study indicate that a cautious driving style alone may not be sufficient to compensate for older drivers’ declining functions, particularly the loss of two visual functions observed in the present study.

DOI： 10.1016/j.trf.2024.05.019

Web of Science

Scopus

出版者・発行元：Sustainability Switzerland  

Carsharing has received considerable attention as a sustainable mobility paradigm. Various service designs and dynamic business environments have increased the decision complexity for the carsharing business. Therefore, carsharing operators require a tool for assessing business development from holistic perspectives. This research provides a framework for outlining the requirements of the carsharing system with holistic perspectives of stakeholders being considered, as well as to derive assessment metrics for examining carsharing development. To create the framework, the system modeling tool, context diagram, was adopted to map out the interactions of externalities with the system and the requirements of the system. Eight assessment metrics: the market condition, business advantage, parking condition, electric vehicle deployment, self-serving configuration, vehicle reservation, vehicle maintenance, and pricing scheme, were eventually identified from the system modeling. From these dimensions, we review 24 carsharing cases from China, Europe, Japan, and the United States, and we summarize discrepancies among different marketplaces and some managerial insights on carsharing development, such as carsharing motivators and inhibitors, innovations in respect of different business backgrounds, approaches of increasing parking privileges, approaches of increasing electrifications, essential digital features, reservation regimes, methods of vehicle maintenances, and service pricing regimes.

DOI： 10.3390/su16103994

Open Access

Web of Science

Scopus

出版者・発行元：Journal of Intelligent Transportation Systems Technology Planning and Operations  

The global positioning system (GPS) trajectory data are extensively utilized in various fields, such as driving behavior analysis, vehicle navigation systems, and traffic management. GPS sensors installed in numerous driving recorders and smartphones facilitate data collection on a large-scale in a high-frequency manner. Therefore, map-matching algorithms are indispensable to identify the GPS trajectories on a road network. Although the local map-matching algorithm reduces computation time, it lacks sufficient accuracy. Conversely, the global map-matching algorithm enhances matching accuracy; however, the computations are time consuming in the case of large-scale data. Therefore, this study proposes a method to improve the accuracy of the local map-matching algorithm without affecting its efficiency. The proposed method first executes the incremental map-matching algorithm. It then identifies the mismatching links in the results based on the connectivity of the links. Finally, the shortest path algorithm and the longest common subsequence are used to correct these error links. An elderly driver’s driving recorder data were used to conduct the experiment to compare the proposed method with four state-of-the-art map-matching algorithms in terms of accuracy and efficiency. The experimental results indicate that the proposed method can significantly increase the accuracy and efficiency of the map-matching process when considering high-frequency and large-scale data. Particularly, compared with the two-benchmark global map-matching algorithms, the proposed method can reduce the error rate of map-matching by nearly half, only consuming 18% and 58% of the computation time of the two global algorithms, respectively.

DOI： 10.1080/15472450.2022.2086805

Web of Science

Scopus

PubMed

出版者・発行元：IEEE Transactions on Intelligent Transportation Systems  

Driving style assessment plays an important role in intelligent transportation system (ITS) applications, such as driving feedback provision and usage-based insurance. Many previous studies used supervised algorithms to profile drivers. However, this cannot be applied to large-scale unlabeled driving data, which are increasingly prevalent in the ITS context. This paper proposes a framework that combines lateral and longitudinal accelerations to assess a driver's driving style using an unsupervised approach. The framework first detects risky acceleration maneuvers using a statistical method based on the G-G diagram that shows combinations of lateral and longitudinal accelerations. Hierarchical clustering was used to classify the average driving behavior of drivers into high-, medium-, and low-risk groups. Further, a unique Gaussian mixture model is trained for each driver to score their driving style and decompose risky acceleration maneuvers into several risk components. Finally, the spatio-temporal characteristics are extracted to provide implicit factors on the risky behavior of drivers. The proposed method was applied to a large-scale dataset obtained by in-vehicle data recorders. The results demonstrate the necessity to combine the two axes of acceleration for driver behavior assessment. The proposed method can model individual driving styles effectively from the driver's G-G diagram, enabling applicability to large-scale unlabeled data for driving style assessment. The extraction of spatio-temporal characteristics can improve the interpretability of the results obtained using machine learning algorithms. All these results can be used to create a driver's risk profile and provide tailored feedback for improving driving safety.

DOI： 10.1109/TITS.2023.3310213

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  

<p>本研究は，全国的に交通事故の危険度が高い愛知県における交通安全対策に寄与するために，Hierarchical ordered probit モデルを用いて交差点での自動車相互の交通人身事故における当事者の重傷度要因分析を行う．過失の軽重による当事者区分を反映することや，従来の頻度分析においても検討された地域特性を考慮することで，事故の多面的な理解を目指す．推定結果から，高齢者自身，若者や高齢者の相手，相手との車両重量差，正面衝突や右折，夜間の薄暗い状態，交差点規模，故障信号機，内部照明式拡大標識，田農用地，人口集中地区，過疎地域などの説明変数が重傷度に有意に影響を及ぼすことが明らかとなった．また，閾値に変数を加えることで，自身の年齢などの重傷度に部分的に影響する要因を特定した．</p>

DOI： 10.2208/jscejj.24-20019

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>COVID-19 の沈静化に伴い，企業にとっても働く人にとってもテレワークの在り方を見直す時期に来ている．本研究では，働く人へのテレワークの影響について主観的幸福感に着目し，アンケート調査データを用いて構造方程式モデルを構築した．その結果，テレワークが直接的に主観的幸福感に影響を及ぼさないことが明らかとなった．しかし，仕事によるストレス，仕事への熱意，ワークライフバランス，及び移動時幸福感を経由し，間接的に主観的幸福感に影響することが示された．さらに，サテライトオフィス勤務が仕事への熱意に正の影響を与えること，在宅勤務を希望しているのに実施できない場合に仕事への熱意に負の影響を及ぼすことなどが確認された．</p>

DOI： 10.2208/jscejj.24-20131

CiNii Research

出版者・発行元：Asian Transport Studies  

Electric mobility is a potential solution to address the environmental challenges posed by climate change. In addition, car-sharing can serve as a solution to local problems, such as traffic congestion and parking pressure in nonurban areas. Although electric vehicles (EVs) are becoming more common in car-sharing fleets globally, the momentum is less prominent in Japan. In this study, the potential of EV sharing to serve domestic tourists in Japan's nonurban areas was investigated by examining tourists’ choices in transportation mode to reach their destinations and the use of EV sharing after arrival. A hybrid choice model was specified to analyze the effects of observed and latent factors on tourists’ behavior. Although the analysis results generally indicate strong obstacles to EV sharing, reducing the cost of access to EV-sharing services in nonurban areas where public transportation and parking services are limited could increase potential demand.

DOI： 10.1016/j.eastsj.2024.100141

Open Access

Web of Science

Scopus

記述言語：英語   出版者・発行元：Journal of Japan Society of Civil Engineers  

Subjective evaluation of individuals is crucial for adopting new mobility services. This study aims to understand the acceptability of two newly emerged personal e-mobility services—shared e-motorcycle and e-scooter services—and the subjective evaluations underlying their acceptability. A questionnaire survey was administered across Japan in December 2023 to understand the factors underlying acceptability. The survey included questions about the acceptance of shared e-motorcycles and e-scooters and questions related to measuring subjective factors, trust, perceived usability, positive and negative perceptions, and positive and negative affect. An ordered probit model was used to identify factors influencing acceptability. The results showed that subjective factors, such as experience with similar existing services, trust in the new mobility service, perceived usability, system usability scale, and positive and negative perceptions of the new mobility service, significantly affected an individual’s acceptability. For instance, an individual’s experience with bicycle sharing increases their intention to use e-motorcycles and share scooters. In addition, individuals who trust mobility and sharing services are more likely to use shared personal e-mobility services. The use of shared e-motorcycles and e-scooters was significantly driven by perceived usability—related to easy access to shared mobility. Finally, positive perceptions of personal e-mobility sharing significantly increased acceptability, whereas negative perceptions had the opposite effect.

DOI： 10.2208/journalofjsce.24-20037

Scopus

CiNii Research

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

<p>The COVID-19 pandemic has accelerated changes in work styles, particularly leading to an increase in teleworking. This increase has the potential to affect transportation and urban development. In Japan, as telework is gaining popularity with more companies implementing telework systems, the choice of workplaces has become diverse. This study investigates factors influencing workers’ time allocation among different workplaces, such as offices, satellite offices, and homes. A time allocation model is applied to the data collected by the web-based survey, which includes social demographics, evaluation of the work environment, and psychological factors related to work-life balance. The estimation results indicate that socio-demographic attributes, job type, work characteristics, work efficiency, work-life interruption, recreation intention, and work environment satisfaction significantly affect the time allocation among different workplaces.</p>

DOI： 10.11175/easts.15.179

CiNii Research

出版者・発行元：Transportation Research Record  

This study investigates which factors can influence bicycle accidents for a variety of age groups at the traffic analysis zone level. The cyclists were divided into four age groups: child, young, adult, and elderly. To accommodate for the potential variation in the influence of exogenous factors for these age groups, we utilized the multivariate Poisson gamma mixture model. The formulated model not only incorporates the heterogeneity and over-dispersion of the unobserved factors but also allows for the variance of the covariance between the age groups among the zones. The zone-level variables considered in this study include sociodemographic characteristics, socioeconomic characteristics, the built environment, road network characteristics, and traffic characteristics. The model was estimated using bicycle accident data for the year 2011 in Nagoya, Japan. The estimated results clarify the impacts of the explanatory variables for the respective age groups. Children tend to experience more accidents in their residential zones, while the young and adult age groups have more accidents in zones that have many companies. All age groups are more likely to have accidents in the area of many shops. The elderly group is greatly affected by both the number of bicycle trips and its spatial spillover effect, implying that they are most prone to bicycle accidents among all age groups. The findings of this research can assist decision-makers in making proactive decisions to improve bicycle safety.

DOI： 10.1177/03611981221143378

Web of Science

Scopus

出版者・発行元：Transportation Research Record  

The serviceability of a road network often faces challenges of traffic congestion and natural disasters which can damage the performance of many links within the network. To ensure the high performance of a road network, it is essential to identify and protect the critical links which if disrupted will cause substantial damage to the network. This study analyzes the vulnerability of the road network of the city of Casablanca in Morocco. Capacity weighted spectral analysis of the graph Laplacian is used to evaluate the road network vulnerability and identify potential critical links. We consider two cases concerning the weight definition: capacity weighted without considering travel demand and reserve capacity weighted with consideration of travel demand. After finding the critical links of the network, we investigate its vulnerability with consideration of a future tramway project. We compare two cases: the road network with the current tramway lines and that including two additional tramway lines planned for the future. The results show shifts in the critical links between the two cases. Furthermore, an increase in vulnerability is observed after the construction of the new tramway lines if no measures are taken to maintain the corresponding link capacities.

DOI： 10.1177/03611981221110565

Web of Science

Scopus

記述言語：英語   出版者・発行元：The City Planning Institute of Japan  

<p>The COVID-19 pandemic and the resultant preventive measures worldwide have accelerated a change in the way millions of people work. Telework became necessary to prevent the spread of coronavirus and reduce office workers’ health risk. The change in employees’ workstyle may directly impact commuters’ travel behavior, which affects individuals’ residential area choices and companies’ office location choices, ultimately affecting urban development and transportation infrastructures. This research aims to investigate preferences for telework among Japanese employees and, in hybrid workstyles, identify the factors that affect the best trade-off between commuting-based work and telework. A web-based questionnaire collected data which was analyzed using ordered probit modeling. Results revealed that 25% of non-telecommuters want to switch to telework and that the number of workers who want 100% telework increased from 4.9% to 8%. Regression analysis showed a strong influence of socioeconomic and demographic characteristics on the choice between commuting and ICT-based work. Results of this study make it possible to understand office workers’ intentions to work remotely and predict how this will affect economic activity distribution within urban areas. It is also possible to consider an actual case of the implementation of ICT infrastructure for specific segments of society.</p>

DOI： 10.14398/urpr.10.179

CiNii Research

出版者・発行元：IEEE Conference on Intelligent Transportation Systems Proceedings ITSC  

This paper proposes a novel method to classify drivers' driving styles based on G-G diagrams that display the lateral and longitudinal accelerations on the x- and y-axes. A data-based safe driving area was defined to distinguish risky acceleration points from safe acceleration points. The Jensen-Shannon divergence was used to measure the similarity between the distributions of data points outside the safe driving area. A hierarchical clustering algorithm was used to classify the drivers into two groups based on similarity: non-aggressive and aggressive groups. To verify the proposed method, we used the naturalistic driving data of 71 drivers. The results indicated that the proposed method could help understand the risk level of drivers and individual differences in their driving styles. Drivers in the aggressive group exhibited diverse types of risky driving styles, and the percentage of points outside the safe driving area was much higher than that for the low-risk group. The proposed method can be applied in driving performance feedback provision, fleet management, and usage-based insurance.

DOI： 10.1109/ITSC57777.2023.10421864

Web of Science

Scopus

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

<p>Before the final advent of Robo-taxi, careful preparations for integrating the Robo-taxi into society and understanding how travelers value the Robo-taxi against other travel modes are indispensable. To this end, a stated preference (SP) survey was conducted to understand people’s travel mode choice behavior for commuting, shopping, and hospital visiting. Besides, a reveal preference (RP) survey was supplemented to improve the robustness of parameter estimation. We investigated the effect of the socio-demographic, travel attribute, Robo-taxi feature, and latent variables on the mode choice behavior for the three typical travel purposes by the hybrid choice model. The results showed that old people prefer using Robo-taxi for commuting and hospital visiting, while not for shopping; the high ride-sharing rate of Robo-taxi will impede the willingness to use for shopping; reliability, perception of personal benefit as well as social benefit exert positive effect on Robo-taxi usage across all purposes.</p>

DOI： 10.11175/easts.14.1019

CiNii Research

出版者・発行元：Asian Transport Studies  

With the aging of the population, the number of elderly drivers is increasing. Elderly drivers tend to overestimate their driving abilities, despite their maneuvering skills and cognitive function worsening with aging. Therefore, understanding the driving behavior of older drivers is becoming increasingly important for assisting their safe driving. This research analyzes the characteristics of old drivers' driving behaviors by utilizing the GPS trajectory data collected by the driving recorders installed in their vehicles. The analysis conducted was from the perspectives of route choice, driving time, driving distance, risky driving event, and driving speed. Furthermore, a linear regression model was used to explore the influence of drivers’ socioeconomic attributes and travel behaviors on driving speed. The results show that older drivers prefer short-distance travel in the daytime and tend to have more risky driving behaviors with aging.

DOI： 10.1016/j.eastsj.2022.100063

Open Access

Web of Science

Scopus

出版者・発行元：Transportation Research Part A Policy and Practice  

This study aims to measure the causal relationship between three railway projects in different regions of Nagoya city and the residential distribution of different households. Rather than assuming that a railway project has an identical impact on all the neighborhoods in the treated group, this study proposes a heterogeneous difference-in-differences estimator to account for the heterogeneity in the treatment group, which is caused by different land cover characteristics. Specifically, the possible local spatial spillover effects are emphasized. The empirical application results indicate that (1) the northern neighborhoods near the Meijo and Aonami lines are attractive to households with higher income, (2) the southern neighborhoods near the Meijo line are appealing to middle-income households, (3) the low-income and old-single households prefer the southern neighborhoods along the Aonami line, and (4) the couple-with-children and old-couple households with lower income prefer to live around the Sakura-dori line. To conclude, railway-oriented communities, with different land use characteristics, attract different household types. This study's findings have implications for policymakers, city planners, and scholars.

DOI： 10.1016/j.tra.2021.10.004

Web of Science

Scopus

出版者・発行元：Journal of Transport and Land Use  

Previous studies have proven the significant causal relationship between railway investment and gentrification in some cities. However, most of them have focused on the gentry and less on the effect on other social classes. To observe how railway investment affects neighborhood change for different population types, this study investigated the investment effects of two urban railway lines separately on the neighborhood change of the gentry, older population, and students in Nagoya, Japan. These two railway lines consisting of a subway and an elevated railway opened in the same year and were located in different areas of the city. Moreover, the spatial autocorrelation in panel data was considered to investigate possible local spillover effects. Finally, we observed that the railway investments in highly urbanized areas were more likely to induce gentrification. In addition, railway investment has some significant treatment effects on students compared to the older population.

DOI： 10.5198/jtlu.2021.1763

Open Access

Web of Science

Scopus

出版者・発行元：Asian Transport Studies  

The transit-induced residential gentrification caused by two urban rail transit lines in Nagoya, Japan is investigated individually. The difference-in-differences model, a quasi-experimental model, is used to explore the possible causal relationship between rail investments and residential gentrification. Two rail transit lines, which consist of subway and elevated railways, began operation in the same year and during a period of economic downturn. Investigations reveal that these rail transit lines located in different areas have achieved their own geographic scales of influence. Furthermore, the results show that the rail transit line located at the center of Nagoya causes a significant change in the household income of nearby neighborhoods, while evidence of transit-induced residential gentrification is not found for the suburb of Nagoya.

DOI： 10.1016/j.eastsj.2020.100022

Open Access

Scopus

記述言語：英語   出版者・発行元：公益社団法人 日本都市計画学会  

本研究は、2006年から2015年の間に名古屋市中心市街地で発生した自転車事故データを用いて、交差点構造及び自転車道路が自転車事故に与える影響を分析した。自転車の保有率が増加する中、自転車事故が全交通事故件数に占める割合は対象期間中毎年25%を上回っている。自転車事故の多くは交通量の交差が多い交差点で起きているため、本研究では交差点での事故を対象とし、交差点構造データ及び自転車道路データを収集し、これらの要素が自転車事故発生に及ぼす影響を負の二項分布モデルを用いて分析した。モデルの推定結果により、大きい交差点ほど自転車事故リスクが高いことと、小さくてもストップサインのみの交差点は自転車事故リスクが高いことがわかった。更に、単路から交差点横断部分まで明確に標示されている自転車道路による周辺交差点の自転車事故減少効果が有意であることが示された。

DOI： 10.11361/cpijchubu.31.0_31

Open Access

CiNii Research

出版者・発行元：Sustainability Switzerland  

Understanding the influence areas for transit stations in Indian cities is a prerequisite for adopting transit-oriented development (TOD). This study provides insights into the last mile patterns for selected Delhi Metro Rail (DMR) stations, specifically, Karkardooma, Dwarka Mor, Lajpat Nagar, and Vaishali, and the extent of the influence area based on different access modes. The variation in the extent of the influence areas based on various modes and the locational characteristics of stations have been considered in this study. The last mile distances reported in the conducted survey involved the problems of rounding and heaping, and they were subjected to multiple imputation to remove the bias. The spatial extent of the influence areas for various modes was estimated based on the compound power exponential distance decay function. Further, the threshold walking distances were calculated using the receiver operating characteristic (ROC) curves. The variations were noted in the last mile distances among stations. The walking distances (mean and 85th percentile) among stations did not vary considerably; however, large variations were noted when comparing other modes. These differences in accessibility must be taken into account when considering multimodal accessibility and multimode-based TOD. The study can provide useful inputs for planning and implementing TOD in New Delhi.

DOI： 10.3390/su11164295

Open Access

Web of Science

Scopus

出版者・発行元：Sustainability Switzerland  

As Indian cities adopt the concept of transit-oriented development (TOD), concerns have arisen regarding the applicability of TOD standards formulated in developed countries in the Indian context. This study aims to estimate the TOD influence areas in New Delhi by examining the last mile connectivity patterns of passengers on the Delhi Metro Railway (DMR). Questionnaire surveys conducted on the last mile connectivity reveals use of various access modes for metro stations in India, although current research only considers walking and cycling to be universal forms of access. Therefore, this study focuses on the DMR's multimodal accessibility to investigate the last mile distance of each mode. In order to offset the rounding errors of reported distance, a heaping model and multiple imputation (MI) were employed to improve the accuracy of the reported distance. Afterward, distance decay analysis and receiver operating characteristic (ROC) curves were used to determine the thresholds of last mile distances. The findings show that the influence area differs across travel modes and increases in the order of walking, informal transit, buses, and private transport, respectively.

DOI： 10.3390/su11092621

Open Access

Web of Science

Scopus

出版者・発行元：Journal of Transport and Land Use  

Transit oriented development (TOD) is a land-use and transport integrated urban planning strategy that is highly acclaimed for promoting sustainable city development. This review aims to identify the problems regarding adoption of TOD standards or guidelines formulated by developed countries in developing countries, such as India, and the necessity of conducting adaptability studies on TOD influence areas. The existing studies show that the size of the influence area varies among different cities and travel modes. Accordingly, no single size influence zone is suitable for all cases. This review highlights the necessity of carefully considering the spatial extent of influence areas and modes other than walking as access or egress modes in the Indian context. Moreover, this review aims to provide insight on how to plan TOD in the context of developing countries, because the mobility patterns in these countries differ considerably from those in the developed world.

DOI： 10.5198/jtlu.2019.1534

Open Access

Web of Science

Scopus

出版者・発行元：Eastern Asia Society for Transportation Studies  

<p>The effects of the opening of two urban railway lines on residential gentrification in Nagoya, Japan, are separately investigated. The difference-in-differences model, a quasi-experimental model, is applied to explore the possible causal relationship between rail investments and residential gentrification. Two rail transit lines, which consist of subway and elevated railway, have been opened in the same year in a period of economic downturn. The analysis results reveal that these railway lines located in different areas have achieved their own geographic scale of influence. Furthermore, the analysis points that the railway line located in the center of Nagoya produces a significant change in household income in the nearby neighborhoods, while evidence of transit-induced residential gentrification is not found for the suburb of Nagoya.</p>

DOI： 10.11175/easts.13.463

CiNii Research

DOI： https://doi.org/10.2208/jscejd.63.302

担当区分：筆頭著者  

DOI： https://doi.org/10.1016/j.tra.2003.11.004.

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.2208/journalip.19.513