JSTE Journal of Traffic Engineering
Online ISSN : 2187-2929
ISSN-L : 2187-2929
Volume 6 , Issue 2
Showing 1-48 articles out of 48 articles from the selected issue
Special Edition A (Research Paper)
  • Kota NAGASAKI, Wataru NAKANISHI, Yasuo ASAKURA
    2020 Volume 6 Issue 2 Pages A_1-A_8
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    A road network around a railway station may affect the convenience of the station. However, only few researches have evaluated or classified a road network around a specific facility with referring to tangible factors of a road network such as length or orientation of each road link. In this paper, we propose a new evaluation method of a road network by using directional statistics. At first, we draw a rose diagram focusing on orientation of road link around a station. Next, we estimate parameters of circular distribution of the orientation and evaluate characteristics of the network by using the parameter values. The proposed model is applied to the road networks around all 21 stations on Tokyu Toyoko line. In comparison with the past studies, this method represents how the link orientations concentrate to specific directions. In addition, it becomes possible to classify road networks into several categories with similar parameter values.

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  • Hiroyuki KONDA, Hideki NAKAMURA
    2020 Volume 6 Issue 2 Pages A_9-A_15
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    This study assumed that maneuverability such as car-following status illustrates an element related to driver perception, and investigated a performance measure capable of expressing the maneuverability as the quality of service of traffic flow (QOS). Follower percentage is such an index obtained by estimating the composite headway distribution consisting of follower and non-follower headway elements and is used as a performance measure that expresses car-following status. Analysis of pulse data obtained from vehicle detectors at multiple points on intercity expressways with different geometric structures and lane operations showed that follower percentage is influenced by lane traffic volume, vehicle pair, and lane operation. It is clarified that follower percentage can realistically express the behavioral characteristics of small and large vehicles, respectively, and probabilistically capture followers according to the actual traffic phenomenon. Thus, it can be concluded that follower percentage is a suitable index for evaluating the quality of service of traffic flow on intercity expressways under non-congested flow conditions.

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  • Makoto KASAI, Jian XING
    2020 Volume 6 Issue 2 Pages A_16-A_22
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    This study proposes a hierarchical regression model to predict spot speed on Two-way Two-lane (TWTL) expressways. The model has two explanatory variables: longitudinal gradient and the distance from the start point of TWTL. The values of explanatory variables are estimated every rank of traffic flow rate and every TWTL route. To take heterogeneity of the effect of traffic flow rate rank and route on spot speed into account, a hierarchical model is assumed. Speed profile data on 4 TWTL routes in Japan obtained from ETC2.0 probe data are used for calibration and cross-validation; data on inbound direction is for calibration of the model while that of outbound is for cross-validation. As a result of the calibration, the root mean square error (RMSE) between the actual speed and estimated speed is lower than 6 km/h under 600-800pcu/h for section of calibration. The RMSE on cross-validation is also lower than 6km/h. There are some other findings in the analyzation; for instance, the coefficient of longitudinal gradient becomes large when traffic flow rate increases.

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  • Dai SOMA, Tetsuro HYODO
    2020 Volume 6 Issue 2 Pages A_23-A_30
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In recent years, the shortage of truck drivers has become a problem in the logistics industry because of an increase in cargo volume, aging drivers, and a shortage of young drivers. In order to improve these problems, a Longer and Heavier Vehicle (LHV) (which will be referred to as “21m-long truck” in this paper) was introduced. This 21m-long truck can carry about twice as many cargo volume as a regular truck, so it is expected to be one of the solutions in the logistics industry which has a problem of serious labor shortages. In addition, an advantage that can be considered for the global environment, is reducing carbon dioxide emissions per thousand ton-kilometer. In this study, we handle GPS data of 21m-long truck and the driver's heart rate data. The high accelerations observed with GPS data were plotted on a map, the observed points were examined, the relationship with how the driver is stressed was clarified, and the safety of 21m-long truck operation could be confirmed.

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  • Katsuhiro IIDA, Kaito YOSHIMURA, Kazumi RENGE, Masahiro TADA, Hideki T ...
    2020 Volume 6 Issue 2 Pages A_31-A_40
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    This paper analyzed relationships between driver’s anxiety and unsafe driving tendency in order to enable risk assessment of potential traffic accidents. Using an indoor driving simulator, we collected the vehicle behavior data. Additionally, we collected levels of anxiety by interviewing the examinees after the completion of every test run. The examinees were classified via cluster analysis (Ward’s method) using their level of anxiety. It was found that, when the examinees were classified into three clusters, the classification was the easiest to interpret. So we focused on the examinees who changed their level of anxiety drastically between the different course conditions. Based on the results of the analysis of variance of jerk and distance from the center of the lane, we established that there are positive relationships between anxiety and unsafe driving tendency. Furthermore, on the basis of analysis of maximum acceleration, we confirmed that unsafe driving tendency tended to be the source of unsafe behavior, though this tendency was only partially verified.

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  • Kazuhide NODA, Sachiko OHASHI, Hiroshi KOBAYASHI
    2020 Volume 6 Issue 2 Pages A_41-A_47
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    Installation of traffic calming devices is effective as a traffic safety measure on residential roads. In “Technical standards for installing Humps, Narrowings and Chicanes”, the standard shape of hump that is effective for vehicle speed control was shown. On the other hand, there are various road structures and roadside environments of residential roads, it is necessary to have knowledge on various shapes of devices and installation methods that can be adapted to each road. Therefore, in this study, focusing on vehicular speed can be reduced even humps with flat part length assuming installation at the intersection etc, a traffic experiment was conducted with a plurality of humps with different flat part lengths, and the vehicle speed control effect and vehicle behavior differences of the humps with different flat part lengths were confirmed. In addition, a questionnaire survey was conducted to understand driver awareness during hump traffic, investigate the difficulty of speeding up to high speeds, the difficulty of driving and expected effects when installing each hump on actual roads.

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  • Katsuhiro IIDA, Takaki ENDO, Masahiro TADA, Kazumi RENGE, Takashi YAMA ...
    2020 Volume 6 Issue 2 Pages A_48-A_54
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    Junction of the deep underground expressway which is currently under construction has a specific road structure that steep slopes, sharp curves and split or merge points are concentrated in a short section. It has been proved in a previous study that driver's load increases by targets of attention concentrated at bifurcation area due to lack of information on downstream side of the successive branches. In addition, it has been suggested that it also induces rapid deceleration at the bifurcation. In this study, application of color-coordinated destination indicators as a guidance method not solely depending on traffic guide signs has been examined as a possible countermeasure against abovementioned problems. Upon analysis of behaviors of vehicles and drivers obtained from indoor driving experiment using the driving simulator, effectiveness of the color-coordinated destination indicators as a countermeasure against the problems have been verified. As a result, it has been confirmed that the color-coordinated destination indicators may make driver recognize the course earlier and that it reduces driver's load at bifurcation area eliminating the rapid deceleration factor.

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  • Masami YANAGIHARA, Kenta HIRAKI, Hiroyuki ONEYAMA
    2020 Volume 6 Issue 2 Pages A_55-A_62
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    Moving Light Guide System for the purpose of the speed control by the blinking of plural LED panels attracts attention as a traffic jam measures for the traffic concentration at the incline change point of the expressway. Increase of the flow rate or decrease of the traffic jam quantity are confirmed indeed. However, there are few studies about the influence that a change of the following behavior and also a change of the whole traffic state with the Moving Light Guide System. Influence on whole traffic state by the introduction of the Moving Light Guide System is analyzed for the purpose of clarifying the effect of the introduction after having considered the change of following behavior in this study. Specifically, it was supposed that following behavior was different in having setting or not of the Moving Light Guide System, and the comparison of the traffic state was done by micro traffic simulation experiments based on different following models calibrated by actual survey data on road with or without the Moving Light Guide System.

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  • Yasutaka SHIMODA, Jun TERAOKU, Shuto TANAKA, Akinori MORIMOTO
    2020 Volume 6 Issue 2 Pages A_63-A_70
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In cities where many people gather, it is necessary to realize better public security, safety and security. The Metropolitan Police Department is envisioning the advancement, speed, and efficiency of police activities and the prevention of crimes and traffic accidents by predicting in advance. In the implementation of evidence-based policies, police need to determine the amount of street policing input based on the results of predictions. However, the effects of reducing accidents due to crackdowns and street activities are not quantified, and are currently determined at the discretion of police officers. Therefore, in this study, the risk of accidents of control and street activities was quantified by predicting accident risk recursively by multiple regression analysis considering two factors of street control activities and road environmental factors. As a result, Using the established regression model, it was found that crackdown and street activities have the effect of reducing accident risk to a certain extent.

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  • Hironobu HASEGAWA, Sai ITO, Tohru TAMURA
    2020 Volume 6 Issue 2 Pages A_71-A_77
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In Japan, Article 10 of the Road Traffic Law stipulates that pedestrians must use the right edge of a road without sidewalks. It should be noted that there is an exception that when the right side of the road is dangerous or there is no other choice, the pedestrian is allowed to move to the left side of the road, and the decision is left to the pedestrian. Nevertheless, it is not obvious which is safer for pedestrians to walk. Based on the above problem consciousness, this paper proposes a model for the relationship between pedestrians' walking position and the risk of contact with vehicles running straight on the intersection of a residential road where there is no signal, no stop restriction on the vehicle side, and poor visibility. The proposed model was applied for a case study in Iijima-Naganonaka-cho district in Akita City, and quantitative safety evaluation of pedestrians' walking position was tried. As a result of the analysis, it has been found that the left side walking was safer under the condition assumed in this study.

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  • Keisuke MATSUDA, Masami YANAGIHARA, Hiroyuki ONEYAMA
    2020 Volume 6 Issue 2 Pages A_78-A_86
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    Regarding the safety and efficiency of intersections, there are studies focusing on intersection structures and display patterns, but there are few studies focusing on the position of signal lamps, and sufficient knowledge of differences in driving behavior due to differences in lamp positions have not been obtained. Therefore, in this study, focusing on the position of the signal lamp, driving performance differences between the right front and far left (far type), which is mainstream intersections in Japan, and the left front (near type), which is mainstream intersections in Germany etc. Evaluation was made using driving behavior data obtained by experiments using a driving simulator. As indicators for evaluating intersection performance, “passage judgment rate and collision possibility“ and “crossing time difference“ are used for safety, and “traffic capacity at intersection“ is used for efficiency. As a result, it was shown that near type intersection might have higher performance in both safety and efficiency than far type one.

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  • Takumi KANI, Miho IRYO
    2020 Volume 6 Issue 2 Pages A_87-A_96
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In order for autonomous vehicles (AVs) to get public acceptance by pedestrians, it is important not just to technically improve the avoidance performance of AVs to pedestrians, but also for pedestrians to behave properly in front of AVs without overconfidence of their performance. This study aims at clarifying the impact of deceleration maneuver and avoidance performance reliability of AVs on pedestrians’ crossing behavior at unsignalized crosswalks. Virtual reality experiments were conducted so that participants as crossing pedestrians at unsignalized crosswalks experience the approaching AVs with various maneuver and reliability settings. Crossing decisions and their timings, subjective impressions at each trial were collected. A time-dependent pedestrian crossing decision model was developed from the experimental data. The proposed model revealed that not only the expected arrival time of AVs but also the pedestrians’ belief of avoidance reliability and the frequency with which the participants usually give way as drivers affect their crossing decisions.

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  • Rintaro YABUSAKI, Yuki MORISHIGE, Akinori MORIMOTO
    2020 Volume 6 Issue 2 Pages A_97-A_104
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    During the last half century, the bicycle use environments have undergone significant changes in Japan. In order to examine the development of bicycle use environments based on lifestyle changes, it will be necessary to investigate the relationship between the bicycle use and the socioeconomic changes. Therefore, this research has grasped longterm changes in the bicycle use by using data from the Tokyo Metropolitan Area Person Trip survey conducted five times in the past. Using the analysis method ‘BayesLiNGAM’ and Covariance Structure Analysis, we have revealed the causal relationship between changes in the bicycle use and the socioeconomic changes. As a result, it was shown that the increase in bicycle use by women in their 40s and 60s in the 1980s was understood. Furthermore, the causal relationship that healthy traffic behavior and pottering increased due to the increase of bicycle uses by white-collar workers who mainly work at the office in the 2000s was clarified.

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  • Shun OKANO, Koki TAKAYAMA, Kiyohiro MIURA, Akinori MORIMOTO
    2020 Volume 6 Issue 2 Pages A_105-A_112
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    Autonomous vehicles are expected to contribute to improving traffic convenience in various ways, such as reducing traffic accidents and eliminating traffic congestion. However, when autonomous vehicles are driven on ordinary streets, the demand for pick-up cars by individual movement increases and the demand for stopping on the street space may increase. And traffic jams and delays may occur in the street space. In this study, a micro-traffic simulator was used to examine the street space in an autonomous driving society based on quantitative data, using the value of time and travel speed, which is slower than the free flow. Focusing on the boarding environment of autonomous vehicles and created scenarios that changed the boarding environment such as traffic spaces and curbside and analyzed them. As a result, it was found that on-street parking type landings can be used on streets with low traffic, but bus stop type landings should be prepared on streets with a certain amount of traffic.

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  • Miki MATSUMOTO, Nobuhiro UNO, Toshiyuki NAKAMURA, Jan-Dirk Schmöcker
    2020 Volume 6 Issue 2 Pages A_113-A_120
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    The purpose of this study is to analyze the maneuvering of drivers during a takeover request from automated control with driving simulator experiments. With a focus on Level 3 autonomous vehicles and investigated the effect of conducting a second task and the traffic conditions on drivers’ behavior. This includes studying their eye movement before, during and after the mode switching from autonomous to manual driving. We also analyzed the effects of differences in surrounding traffic information provision. It was found that the time to grip the steering wheel was shorter when there was a second task than when there was no second task. Further, the time to grip the steering wheel and the ratio between gazing forward or at the video are affected by providing information regarding the need to pay attention to the surroundings when the driver is performing a second task in a situation with heavy traffic.

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  • Reiya MATSUGATANI, Yasuhiro SHIOMI, Jian XING, Fumihiro ITOSHIMA, Hoda ...
    2020 Volume 6 Issue 2 Pages A_121-A_130
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    It has been reported that the traffic capacity at freeways are decreasing trend in the last decade. To come up with a viable countermeasure to mitigate traffic congestion and related traffic accident, it is essential to reveal the details of the mechanism of the decreasing trend of traffic capacity. In this study, by using the individual vehicle data, which is collected by traffic detectors in the two-different time cross sections, the differences of the driving characteristics (that is, lane-flow distribution, following time headway distribution, time to collision (TTC), desired speed distribution, and platoon size distribution) between the cross sections are compared. As a result, it is shown that the proportion of traffic volume of the median lane, the following time headway and TTC tend to be larger, whereas the desired speed distribution and platoon size tend to be smaller. These changes of driving behaviors might affect the negative impact of traffic capacity.

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  • Jia YANG, Yasuhiro MIMURA, Motohiro YAMAZAKI, Ryosuke ANDO, Kojiro MAT ...
    2020 Volume 6 Issue 2 Pages A_131-A_137
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    It is reported that elder drivers have a high tendency to fail to notice the speed limit sign for their deteriorated visual ability. Especially, elder drivers would cause unintentional speeding in maximum speed decline intersections, when they failed to notice the lower speed limit sign compared to the former road section. Therefore, it is necessary to find some countermeasures for the speeding problem in maximum speed decline intersections. The purpose of this study is to understand the situation of speeding behavior and investigate the speeding reduction effect of advisory intelligent speed adaptation for elder drivers in this type of intersections. The probe data of 10 elderly and 10 nonelderly drivers living in the urban area of Toyota City, Japan are used to understand the change of speeding behavior with and without the provision of speeding alter in maximum speed decline intersections. The major finding suggests that the speeding rate decreased in 3 intersections, and it remained unchanged in two intersections inside the observed five intersections based on the trajectory of elder drivers.

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  • Tatsuki ONOGAWA, Toshiyuki NAKAMURA, Takatsugu HIRAYAMA, Toshihiro HIR ...
    2020 Volume 6 Issue 2 Pages A_138-A_146
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    The urban expressway in Japan has severe road alignment due to constraints in construction. It is assumed that the driver's gaze behavior also changes greatly depending on traffic conditions and roadside environment. It's difficult to measure the gaze behavior of the driver during driving on a daily. There is not enough knowledge about analysis of gaze behavior. This research focused on the roadside and traffic conditions on the Hanshin Expressway, then analyzed changes in driver's gaze behavior through actual expressway and driving simulator experiments. As the results, this research obtained results suggesting that gaze behavior influences the viewability of the side walls, traffic conditions, and the presence of dynamic advertisement information in buildings outside the expressway. These obtained results are expected to contribute as one guideline for considering traffic safety measures by sharing them to road managers for reducing accidents in urban expressway operators. This paper also analyzed the relationship between the gaze behavior and driving behavior of the driver in an urban expressway. Experiment on the expressway and experiment using driving simulator clarified how the road structure such as the side wall and the accompanying gaze of the landscape and the surroundings affect the driving behavior.

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  • Keita SASAKI, Motohiro FUJITA, Wisinee WISETJINDAWAT
    2020 Volume 6 Issue 2 Pages A_147-A_155
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In this study, we constructed road restoration algorithm considering reality and efficiency in order to minimize the damage after a huge earthquake. For this purpose, we supposed some conditions such as damage scale of each roads, restoration works and construction machinery. And we evaluated the importance of each roads to determine the order of road restoration that is not affected by the type of road and location. We also performed simulations under multiple damage assumptions, and compared these results. After that, based on the results, we added some starting points of restoration works to the area where the progress of restoration works were delayed, in order to promote the works. As a result, we compared with the current road restoration plan under the same damage scale and conditions of construction machinery, and it was confirmed that the restoration work progressed in wide area, and the efficiency of transportation of relief supplies. From the above, it can be said that it contributed to the improvement of the reality and efficiency of the road restoration plan.

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  • Atsushi OKAMURA, Seiji HASHIMOTO, Hironobu KITA
    2020 Volume 6 Issue 2 Pages A_156-A_165
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In mountainous area, a various of local public transport are conducted. However, it is not clear what local public transport affects on local residents about settling down in own town. Therefore, this paper cleared the importance of going outdoors for settling down in own town after being not able to drive the car. As a result, it is suggested that it is important for local residents to go outdoors by local public transport or taken to and from by family about settling down in their town after being not able to drive a car. And then, this paper cleared the effect of conducting local public transport on local residents. As a result, it is suggested that conducting local public transport affects local residents to settle down in their town with relived about transportation after being not able to drive a car, the need of local public transport and area reliability.

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  • Satoshi HYODO, Keiichi KOBAYASHI
    2020 Volume 6 Issue 2 Pages A_166-A_174
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In recent years, bicycle-related accidents in Tokyo Metropolitan area have a tendency to increase. In order to understand the characteristic of bicycle-related accidents on major signalized intersections. This study analyzed the relationship both motor vehicle and cyclist traffic flows and the bicycle-related accidents based on the developed bicycle-related accidents frequency models. In this study, seven definitions of traffic exposure were used, including motor vehicle flows aggregated by movement type and aggregated cyclist traffic flows. Generalized linear mixed model was fitted to the data set collected from 58 signalized major intersections in the Tokyo Metropolitan area. This study showed that cyclist to motor vehicles accident were sensitive to changes in both cyclist and motor vehicle flows. A10% increase in the right and left turn number of motor vehicles that passed through the major intersection would result in a 3.6% and 7.4% increase in the accident occurrence respectively. Furthermore, a 10% increase in bicycle flow was associated with a 3.8% increase in the frequency of accidents.

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  • Hirotoshi SHIRAYANAGI, Toshio YOSHII, Shinya KURAUCHI, Takahiro TSUBOT ...
    2020 Volume 6 Issue 2 Pages A_175-A_182
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    This study aims to demonstrate that driver’s cognition during driving at night can be improved by attentional momentum effect. Driver’s cognition of a target often delays due to inhibition of return, which is that exogenous attention is suppressed orienting toward previously inspected locations. Previous studies have suggested that attentional momentum effect relieves inhibition of return. It is considered that driver’s exogenous attention tends to be located on roadside -stores with high-illumination intensity which could cause the inhibition of return resulting in the delay in cognition of a target. This study conducts a pre-cueing task based on dual task paradigm to show attentional momentum effect relieves inhibition of return during driving at night. The response time of the attentional momentum condition was observed to be shorter than the inhibition of return condition. This result suggested that attentional momentum effect led to improve the driver’s cognition during driving at night.

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  • Itsuki YOSHIDA
    2020 Volume 6 Issue 2 Pages A_183-A_189
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In Japan, which is facing an aging society and a declining population, there is a need for mobility alternatives to owning private cars. Recently, expectations for MaaS (Mobility-as-a-Service) have increased, and introducing flat-rate services for public transport has attracted attention. However, taxi fares are based on a combination of time and distance, and there is uncertainty in fares even in the same origin-destination. It has different issues from other public transport services. This study estimated frequency of using taxis from the dispatch data of “Mina Taku”service in Minamisoma City, Fukushima Prefecture, which introduces a flat-rate taxi service that limits the days of the week, time of day, and places where passengers can get on and off. In addition, the possibility of improving the frequency of taxi use and increasing revenues of taxi companies by introducing a flat-rate service was shown, and the points to consider when adopting flat-rate taxi services in small provincial cities were clarified.

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  • Takao YANAGIHARA, Daiki KAWAHARA
    2020 Volume 6 Issue 2 Pages A_190-A_197
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    Healthy Japan 21 reported decreasing in walking time of elderly people and necessity of developing accessible environment for elderly people. Study on physical activity and environmental have been reported from Western country. These studies reported that neighborhood environment characteristics, such as residential density, walking facilities, diversity of land use were associated with physical activity. The purpose of this study is to analyze the impact of subjective walking environment on the physical, mental and social health of elderly people in a relatively walking environment in Senboku New Town Sakai City. In this study, physical, mental, social health and subjective neighborhood environments were assessed by basic the health check list and neighborhood environment walkability scale. As a result, physical, mental and social health was associated with subjective walkable neighborhood environment. The subjective walking environment evaluation was different between high active elderly and inactive elderly. Especially, accessibility to shops and stations affected physical, psychological and social health of elderly people.

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  • Yuji KAKIMOTO, Hideki NAKAMURA
    2020 Volume 6 Issue 2 Pages A_198-A_205
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    At the planning stage of road projects, their feasibility is evaluated by the cost-benefit analysis (CBA). In this process, the speed flow relationship (Q-V formula) based on the road type is being used for traffic assignment in Japan. However, in road projects such as grade separation of intersections, if the traffic volume is unchanged through the project, the estimated travel speed is also unchanged, and the effects of the project cannot be properly reflected to the CBA. In this paper, the impact of signalized intersection density on the free speed of the Q-V formula is analyzed by using a traffic simulator. An impact of benefit that is sensitive to the grade separation of intersections by using the calculated free speed is evaluated. As a result, it was confirmed that the free speed of the Q-V formula changes based on the signalized intersection density, the green time ratio and the desired speed. Finally, three benefits of road projects were calculated by a proposed Q-V formula using the free speed based on the signalized intersection density. And the effect of the new formula was clarified by showing the difference in benefits compared to the conventional method.

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  • Ryuichi INADA, Rahman Mursheda, Aya KOJIMA, Hisashi KUBOTA
    2020 Volume 6 Issue 2 Pages A_206-A_215
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In this study, we investigated the relationship between the shape, vertical acceleration and speed suppression effect of humps, which have been installed in various places in reference to the technical standards of the Ministry of Land, Infrastructure, Transport and Tourism. As a result, it was found that some of the cast-in-place asphalt humps were lower in height than the standard, and some of them had a small slope, which did not reproduce the shape of the sine wave, and had a small maximum slope. From the results of the speed survey, it was found that the smaller the uphill maximum gradient, the smaller the speed suppression effect during hump passage. According to the acceleration survey, the vertical acceleration of the backrest of the driver's seat tended to be smaller as the upward maximum gradient was smaller. It is considered that the discomfort caused by the vertical acceleration is reduced and the speed suppressing effect is not sufficiently exerted.

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  • Azusa TORIUMI, Shinji ITSUBO, Kosuke YAMADA, Yuji TAMURA, Yuna MAKI, Y ...
    2020 Volume 6 Issue 2 Pages A_216-A_225
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In this paper, the actual fluctuation of drivers' route choice behavior is analyzed using the data from traffic record collected by the ETC system. Firstly, the relationship between route sharing ratio and travel time of each time zone between junctions are analyzed. The result revealed that the larger travel time difference between two alternative routes is, the larger route sharing ratio of the route with shorter travel time becomes. Furthermore, it was found that if travel time is shorter in one route for most of the time, users are likely to choose it even though the actual travel time is sometimes longer than another route. Secondly we tried to identify the users who do not change their routes based on the change of travel time. It was found that the users who have fixed route choice may have selected the route that is expected to be short in their experience.

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  • Masakazu NAKANISHI, Masato MAEDA, Takashi KODAMA, Kuniaki SASAKI
    2020 Volume 6 Issue 2 Pages A_226-A_234
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    The effects of events that affect road traffic, such as new opening of expressways and toll changes, are generally grasped by comparing before and after indicators such as traffic volume and loss of time. However, there is a possibility that the change in the effect cannot be clearly grasped due to the influence of different day arrangements or the influence of incidents. On the other hand, past studies apply a state space model to traffic volume observed in time series, and classify them into long-term fluctuations, periodic fluctuations, and short-term fluctuations, and analyze traffic characteristics. Therefore, in this paper, we apply the method shown in previous studies, such as classifying the traffic volume observed in time series into each fluctuation component for the traffic situation observed on the Hanshin Expressway. In addition, we will try to clarify the effects of new expressways opening and toll change by grasping long-term fluctuations. We also consider the applicability of the method in practice.

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  • Kota MIYAUCHI, Kazuyuki TAKADA
    2020 Volume 6 Issue 2 Pages A_235-A_243
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    Recently in Japan, due to the aging population, there tends to be an increase in traffic accidents involving the elderly driver. The decline in physical, cognitive, and judgment abilities due to aging contributes to the increase in accidents involving elderly drivers. The technology development of autonomous driving has the potential to compensate for these issues. However, application to general roads is still considered to take a lot of time. Thus, it is essential to develop technologies to help in preventing traffic accidents. This technology requires the vehicle to identify (recognize) the driver. In this study, we construct a method for identifying drivers based on their driving performance. We focused on drivers driving behavior at the intersection because it is complicated to operate through intersections and driving characteristics are remarkably visible. In conclusion, in this study, the proposed method applying Conventional Neural Network (CNN) could identify drivers about high accuracy by drivers.

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  • Edwin AKANDWANAHO, Hideki NAKAMURA
    2020 Volume 6 Issue 2 Pages A_244-A_253
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    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.

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  • Ayumu TAKAHASHI, Takatoshi KAKEI, Hiroshi KOBAYASHI, Yuta OZAKI
    2020 Volume 6 Issue 2 Pages A_254-A_259
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    The “Guideline for Creating a Safe and Pleasant Environment for Bicycle Use” has been issued in November 2012 and the “Bicycle Use Promotion Plan” has also been approved by the cabinet meeting in June 2018. These approaches suggest that grasping the actual use of bicycles is important in promoting the formulation of the bicycle network plan. Among the actual use of bicycles, there is a survey using smartphones as a method for efficiently grasping bicycle route, however the issue is that smartphone observation is not suitable for constant observation. Therefore, in this study, in order to grasp bicycle route by utilizing information and communication technology such as GPS location data which community cycle and share cycle that can be constant observation at all times, we examined the acquisition interval at which the route of the bicycle can be grasped. As a result, we confirm that if GPS location data is acquired at an acquisition interval of about 30 seconds, bicycle route can be grasped.

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  • Yuya TABEI, Teppei OSADA, Nobuaki OHMORI
    2020 Volume 6 Issue 2 Pages A_260-A_269
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    Deterioration of the traffic environment around the large-scale retail store becomes a problem by traffic congestion caused by the location of the large-scale retail store and increase in the traffic accident occurrence number around the store. In this study, we focused on the structure of the parking lot entrance, which is considered as one of the factors of the deterioration of the traffic environment around the large-scale retail store, and analyzed the traffic flow phenomenon of the parking lot entrance by grasping the actual condition of the structure and video camera observation investigation for Utsunomiya City, Tochigi Prefecture. In addition, the accident occurrence situation near the parking lot entrance was analyzed. As the result, this paper clarifies the actual condition that many parking lot entrances become not only a trouble for smooth running of incoming and outgoing vehicles by structural problems, but also a bottleneck of a road in front of a parking lot. In addition, this paper clarifies the actual condition that traffic accidents between automobiles occur more frequently in the vicinity of parking lot entrances and exits with structural problems than those without problems.

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  • Takahiro TSUBOTA, Toshio YOSHII, Hirotoshi SHIRAYANAGI, Shinya KURAUCH ...
    2020 Volume 6 Issue 2 Pages A_270-A_279
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    Accident risk information system aims to reduce traffic accidents by navigating drivers to the routes with lower accident risk. This study quantitatively evaluates the effect of the accident risk information provision by utilizing a dynamic traffic simulation environment – SOUND. The simulation bed is constructed to model the wide-area road network of Matsuyama, Japan. Accident risk estimation models are embedded in the simulation to calculate the timedependent route cost considering the accident risk in addition to conventional cost terms such as travel time. The simulation estimates the traffic conditions when drivers acquire the accident risk information in their route choice. The effect of the information provision system is evaluated by comparing the expected number of accidents with and without the system. The results revealed that the drivers with accident risk information prefer to use routes with lower accident risk, and the total number of accidents could reduce by up to 4%.

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  • Kazushi SANO, Kai WANG, Kiichiro HATOYAMA, Takao TAKAHASHI, Tomonori W ...
    2020 Volume 6 Issue 2 Pages A_280-A_285
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    The taxi system is expected to play an important role, especially in rural areas for an alternative of deficit abolished bus routes and for a kind door-to-door transportation system to aged people. However, it is challenging to keep the taxi service in rural areas; few people want to become taxi drivers because of the lower wages and longer working hours. In that context, it is crucial to increase taxi drivers’ productivity in order to maintain the taxi system in rural areas. In this study, we firstly visualized the taxi service using trajectory GPS data of taxi vehicles in Nagaoka City, Niigata Prefecture and acquired the information contributing to efficient operation. Secondly, a Pickup and Delivery Problem with Time Windows (PDPTW) model was formulated to represent the ideal situation where all reservations have made by the previous days. The optimal number of vehicles and the optimal routes were calculated based on the insertion method, which is one of the heuristic methods. This study further examined the possibility of taxi operational efficiency in the study area.

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  • Jun ITO, Noriyuki SAKAI, Kazushi SANO, Kiichiro HATOYAMA
    2020 Volume 6 Issue 2 Pages A_286-A_295
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    In this research, we analyzed influence of winter weather condition, especially snowfall, on value of travel time. There are two ways to estimate value of travel time: income approach and preference approach. Income approach is usually used for cost-benefit analysis for road construction. However, we adopted preference approach since distress and physical fatigue due to traffic congestion during snowfall may have influence on value of travel time. Specifically, travel history data from ETC 2.0 probe information and route choice data from a questionnaire survey were used to estimate value of travel time. As a result, we found that value of travel time in winter season was significantly higher than that in non-winter season using either travel history data or route choice data. In addition, we confirmed that in winter value of travel time tended to be high even when there was no snowfall. There was a similar tendency for value of time reliability.

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  • Takashi KOBAYASHI, Yoichi SHIMAKAWA, Shigeru KASHIMA, Takayasu KATO
    2020 Volume 6 Issue 2 Pages A_296-A_302
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    This paper aims to propose an estimation method of traffic volume for non-arterial roads that serve as alternate routes of arterial roads. The estimation method uses the correlation “the dependence index on traffic volume of arterial road” between the traffic volumes of the arterial roads and it alternate non-arterial roads. Analysis of the similarity between non-arterial road and arterial road shows that the existence of high dependence road and low dependence road, and the dependence index on traffic volume of arterial road formula is calculated with the use of explanatory variables of the arterial road which include road wideness, link length, and speed limit etc. This result reveals a possibility to add "traffic volume of arterial road" that is observed as explanatory information to traditional variable of estimation method of traffic volume of non-arterial road.

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  • Hirotoshi SHIRAYANAGI, Shinya KURAUCHI, Takahiro TSUBOTA
    2020 Volume 6 Issue 2 Pages A_303-A_309
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    This study aims to demonstrate that driver’s detection of a fallen object on an expressway can be improved by attentional disengagement. Driver’s detection of a target often delays due to vigilance decrement, which is deterioration in the ability to keep attention to a target over a long period of time. Previous studies have suggested that instantaneous attentional disengagement from a target relieves vigilance decrement. It is considered that driver’s attention tends to be located on a particular point in front for a long time which could cause vigilance decrement resulting in the delay in detection of a fallen object on an expressway. This study conducts a selective adaptation task to show that attentional disengagement relieves vigilance decrement during driving on an expressway. The response time of the disengaged condition was observed to be shorter than the engaged condition. This result suggested that attentional disengagement led to improve the driver’s detection of a fallen object during driving on an expressway.

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  • Shohei YASUDA, Takamasa IRYO, Katsuya SAKAI
    2020 Volume 6 Issue 2 Pages A_310-A_316
    Published: February 01, 2020
    Released: February 06, 2020
    JOURNALS FREE ACCESS

    Managing and utilizing traffic data on a large-scale transportation network generally involves a great deal of effort. A network aggregation techniques that simplifies complicated network structures have been developed for efficient analysis of large-scale networks. However, the development of more efficient methodologies is required due to the complexity of processing based only on the patterns of the connection structure of existing methodologies and the enormous computation associated with the setting of link attributes. In recent years, vehicle trajectory data that allows comprehensive observation of network traffic state has been accumulated from GPS equipment. In this study, we propose a methodology for network representation and network aggregation based on actual vehicle flow using longterm vehicle trajectory data. As shown by numerical examples of Japan, the complexity of the structure of the aggregated network is not too simple to lose information under network-wide traffic conditions and not too complex to incur a huge calculating cost.

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