Research on the provision of information about preceding vehicles has been carried out over recent years, showing that environmentally friendly and efficient acceleration on flat roads has become possible. In this stud y, we brought attention to “connecting”, and used a driving simulator to collect and analyse data about the influence on the car-following behaviour that showing the acceleration and deceleration information of preceding vehicles and pre-preceding vehicle s to the driver has. The findings showed that the pre-preceding vehicle information: 1) Caused an 11.1% decrease of pressing down on the pedal, and an 8% reduction of the delay of acceleration, 2) Showed an improvement in the fuel consumption rate 3) According to a comparison by the IDM parameter, caused easier acceleration and deceleration while driving. These results consolidated the experimental results of existing research on a singular pre-preceding vehicle, and as we were able to compare them to driving without the provision of information and with the provision of preceding vehicle information, they re-confirmed that pre-preceding vehicle information is more useful.

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In this study, we propose method that estimate the inflow/outflow vehicle number in the interval. We also propose traffic state estimation method by estimated the inflow/outflow vehicle number. Unlike the freeway, in the general road, the inflow/outflow in the interval affecting the main line traffic. In order to grasp the traffic state in real-time in general road, it is necessary to develop a traffic monitoring method that considering the effect of the inflow/outflow in the interval. Therefore, in this study, it was constructed a state-space model using traffic flow model based on the kinematic wave theory and probe data. This model can estimate inflow/outflow vehicle number in situations that can not be observed inflow/outflow vehicle. Result of model verification by benchmark data, we confirmed that estimated inflow vehicle number is good precision.

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This study carried out driving experiments on safety check behaviors and vehicle movements at five roundabouts in Japan. Specifically, each driver's attention when entering or exiting the intersection was analyzed by using video and drive recorder data. As a result, it is revealed that the safety check speed is positively correlated with the safety check position for both cases of entering and exiting roundabout. And it is also found that the safety check speed of entering roundabout is related to rising slope and the safety check speed of exiting roundabout is influenced by left-turn movement. From the analyses of necessary deceleration rate (NDR) for safety stop before the crosswalk at exit of roundabout, it is found that the existence of crosswalk and splitter island lessen the NDR value, on the other hand, the orthogonal intersection and the narrow apron width raise the NDR value. Especially, the case that there is no crosswalk and splitter island at exit of roundabout and the road with is narrow become high NDR value and unstable movements.

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Mobility services that obviate private automobiles are said to be necessary now and in near future for elderly people who are unable to drive automobiles. Moreover, public transportation, which has heretofore supported city residents, is expected to decline because of motorization development. This study examined the current state of some mobility services and conducted factor analysis of intentions to use them. Results revealed the following. 1) Intentions of using mobility services are related more to personal attributes than to one's place of residence. 2) Some people can be expected to use mobility services if service contents could be improved, but others would be adamantly opposed to using them irrespective of service contents.

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The opportunity of citizen participation and impaired people participation increased after the Transportation Accessibility Improvement Law was enforced. However, continuous citizen participation has a drawback because citizens are not involved at the design, construction, and verification stages.
In this study, we performed process analysis and interviewed the administrative staff and citizens who participated in the community development of the city. Moreover, we clarified a continuous effect of citizen participation and therefore the requirement for citizen participation.
Continuous citizen participation has certain effects on community development such as participation mortgage, qualitative improvement of infrastructure, and cooperation with other themes.
From this consideration, we conclude that the conditions of continued universal design for community development follow three points: 1) system of diverse participation; 2) continuous inspection by citizens; and 3) person for innovation.

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Recently, pedestrian accident at the far side of pedestrian crossing at the unsignalized intersection shares high compared to the near side of it. Two stage crossing could be effective from the viewpoint of safety. Therefore, experiment was conducted to clarify the decision to pass the pedestrian crossing at the mid-section of two way one lane road for each two stage crossing and ordinary crossing. In this experiment, speed of approaching vehicle and timing between the approaching vehicles from both right and left side were changed to set various condition. Distances towards the location that pedestrian was appealed not to pass the pedestrian crossing was used as the index of crossing Result of this experiment shows that two stage crossing has advantages at the far side of pedestrian crossing compared to the ordinary crossing by the decision of subjects. These results could show the safety of two stage crossing at the mid-section of the road without traffic signal.

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This paper describes a case study of scared straight bicycle safety education program (SS) for junior high school students, and impact for their safety awareness of the program by comparing to conventional bicycle education program by conducting police agency. The percentage of correct answer of questionnaire survey conducted at just before, after and one month later from the education program participation has been compared by two-way ANOVA that factors are with/without SS and timing of answer the questionnaire survey. Test results shows that impact to safety awareness of students does not clear difference between SS safety education program and conventional one, but ability for judgement of recognition of dangerous situation for students who participated SS program possible to continually improve rather than those who participated conventional safety education program.

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This study is aimed at analyzing the influence of information on heavy rainfall upon route choice behavior of drivers using real-time navigation devices. This study conducted Web-based survey to collect the data on stated preference of route choice in addition to the one on actual travel experience on focused routes. The estimated parameters of multinomial logit model reveals that the information on heavy rainfall might contribute to enhancement in safety of drivers. It also suggests that the information on risk of inundation and the corresponding route guidance might contribute to safer route choices.

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In the urban expressway, there are many weaving sections. In these areas, traffic capacity is decreased because of complicated lane change. Therefore, weaving sections tend to be bottle-necks of traffic flow. Currently, the solution of this problem is constructing additional lane as a hardware approach, but it caus- es many costs. This study focuses on development of ITS technology. So, under ITS automated driving situation, al-gorithms to avoid vehicle conflicts were proposed. After that, they were tested by a simulation. As a re-sult, it was revealed that the algorithm based on relative indicator contributed to disperse weaving posi-tion, and increase traffic capacity compared to conventional algorithm.

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In Japan, Mandatory ISA (Intelligent Speed Adaptation) or Voluntary ISA will be a new paradigm for the urban driving speed management such as traffic calming in community streets once it is widely disseminated. This study analyzes the effects of various monetary incentive measures and individual attributes on the acceptability of several ISA equipment, by conducting stated preference surveys targeting subjects who had attended in the 5-month Advisory ISA field experiments. The main results are that the acceptability of Advisory ISA is highest followed by Voluntary and then Mandatory, that the acceptability of ISA only targeting community streets is high, that the acceptability becomes higher as the age of the driver become higher, and that the acceptability becomes higher as the amount of the monetary incentive becomes greater, but the marginal effect becomes lower.

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For this study, we administered an interview survey to 610 bicyclists who were legally passing on a sidewalk. They were questioned about which position of the road they would use to pass if the traffic rules were changed to prohibit bicyclists from passing on the sidewalk, which might induce them to pass using a car lane. About 60 percent of male bicyclists and 80 percent of female bicyclists responded that they would also pass on the sidewalk even if it were prohibited because they regarded passing in the car lane as dangerous for bicyclists. The sense of danger of passing using the car lane derives from factors of traffic conditions (car traffic volume and speed, on-street parking, etc.), road conditions (little or no space for bicyclists, etc.), and individual characteristics and circumstances (old age, riding together with a child, etc.). As other reasons for choosing the sidewalk, they pointed out that they would like to avoid circuitous routes and that the guard fences separating the sidewalk and car lane prevent them from moving from the car lane further down the road. We discussed passage space designs for bicyclists which are expected to be acceptable for bicyclists of various types.

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In considering travel route of DRT, numerous variations of route choice sets will be useful information for supervisor. However, to address such a problem, that a combination is enormous like an enumeration of the travel route, traditional enumeration algorithms cannot calculate in feasible time.
This study, travel route of DRT is represented by graph structure, and novel algorithms that enumerate subgraph (all possible paths) on a graph have been proposed. They commonly take advantage of zero-suppressed binary decision diagram which is an efficient data structure for representing family of sets. Also, an applicability of the impact analysis on the network using the enumeration solution is examined.

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This research explores communication between pedestrian and vehicles on road space. This specific research was conducted and analysed based on a series of experiments. As a result, it became evident that active communication from walkers to drivers is highly effective. More importantly, raising hands are more effective than eye contact and bowing for drivers to increase their attention to walkers. This research has also found that cooperative behavior between walkers and drivers are deeply influenced by the speed of automobiles and the act of raising hands. In other words, the faster automobile is, the less we witness cooperative behavior between the two actors. It empirically shows that increasing communication between walkers and drivers will be a valid way to decrease the number of car accidents in the near future.

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Along with population aging phenomenon, the problems of traffic safety of elderly people is increasingly worsening. Unsurprisingly, numerous studies on this issue have been carried out. However, a meta-review to find out global trends of this has not been observed. The goal of this study is to depict an overall picture of the literature based on a meta revision of well over one hundred related studies, in which the most common findings as well as shortcoming issues are identified. A further effort is made to validate those findings in the case of Japan. The results show that aged people are at a remarkably high risk of traffic accidents largely due to their higher frequency of failures, especially among non-automobile travelers. Their failures could be often resulted from the neurological and physical impairments because of the aging effects. Analyses made on statistical data of Japan showed that Japanese older drivers were not in the same situation as their counterparts in other nations, that is they did not have a higher frequency of failures compared to their young counterparts. Interestingly, improper steering and/or braking was the most common cause of failures which result in traffic accident among the elderly, compared to careless driving of all other age groups. From these findings, suggestions for future research to improve traffic safety situation of the elderly in general, and in particular Japanese context are proposed.

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Road sign is the most basis and universal among others guidance systems including car navigation for instance. Until now there are many researches related to road sign's visibility and its design, but not many related to calculation of its guidance effectiveness. Therefore in this research, we developed a model that calculates the percentage (Hereinafter referred to as arrival rate) of drivers who heading to the decided destination relying on only road side along the planned route without missing out from it. Furthermore, we applied this model to a hypothetical road network to calculate the effectiveness of road sign guidance. Also, the effectiveness when setting up more road signs to the same road network is calculated. From this research, the points with low arrival late could be specified. By setting up more road signs to the problem points the improvement in effectiveness of road sign could be quantitatively grasped.

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This study evaluates the long-term changes of traffic capacity on an urban expressway over ten years using the long-term traffic volume data obtained by traffic detectors. Traffic capacity is one of the most important indicators in road management. Traffic capacity mainly depends on factors that does not change over years, such as the geometry of the road, while it can also depend on factors that may change over time, such as vehicle performances and drivers' behaviour. It implies that traffic capacity may not be constant but changing over years. Using the data observed by vehicle detectors of Hanshin expressway from March 2003 to June 2014, long-term changes of traffic capacity were estimated. The capacity was estimated by fitting the observed volume-density data to Drake's formula. In addition, 99 percentile traffic volume in each year was also used to confirm the result estimated by Drake's formula. Checking changes of capacity on several sections, it seems that traffic capacity on most sections has been declining in the last ten years.

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Traffic accident risk must be changed depend on the time of day. It is important to understand this effect on traffic accident risk. In order to carry out effective safety measures, this study investigates the relationship between accident risk and the time of day. After the traffic accident risk of several accident types are calculated based on the hourly traffic volume observed by the census, Poisson regression model is applied to them to investigate the impact of the hourly traffic volume, land use and road structures on the traffic accident risk. As a result, it is shown that the hourly traffic volume has significant impact on the accident risk of all accident types, and the impacts are different tendencies among the 4 accident types. As for the right/left turn accident and the crossing collision, both of the accident risks take the highest value at the certain level of traffic volume. About the rear-ender collision, it tends to increase as the hourly traffic volume increases. On the other hand, about the single vehicle accident, it tends to decrease as the hourly traffic volume increases.

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Recently, the accident rates per vehicle-kilometers is generally used as the likelihood of accident occurrence evaluation unit. The evaluation unit is considered to be proper for a traffic accident on the controlled- access roads such as expressways. On the other hand, it is assumed that the traffic accident on the highways which have intersections are occurred more frequently when the driver passes through an intersection than passing through a basic road section. Therefore, the number of times of passing intersections is considered to be more proper as the evaluation unit than the vehicle-kilometer of travel. In this study, in order to consider the evaluation unit as the accident risk on the highways, a comparative analysis has been conducted to understand how the relationship between vehicle-kilometers and the number of times of passing intersections affect the accidents on highways. As the result of comparative analysis, it shows that the number of times of passing intersections has a strong impact on the multi-vehicle accident and collision of vehicle with pedestrian than the vehicle-kilometer of travel. On the other hand, the vehicle-kilometer of travel has more impact on the single-vehicle accident the number of times of passing intersections.

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In some other countries, Dynamic Speed Display Sign (DSDS), which is an electric sign board displaying current vehicle speed to the driver at specific position using ITS technologies, has been implemented on community streets where it is difficult to install physical devices such as speed hump. While the positive effects of the DSDS have been confirmed in these countries, discussion of how to implement the novel device on community streets in Japan is getting more important. The purpose of this study to grasp fundamental knowledge for implementing the DSDS in Japan through a field test which was carried out on zone 30 in Kariya and Toyota city, Aichi prefecture. As a result, while there was no significant traffic flow difference between non-DSDS and DSDS, there was a significant vehicle speed difference between the two in the long targeted link (almost 150 m). It was also shown that the effectiveness of reducing speed was affected by the contents of the display.

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The time series of travel time variation of highway can be observed easily by ICT devices such as ETC transaction record. This study focused on the travel time variation of a highway where the traffic congestion frequently occurs. This study assumes the cyclic fluctuation is stationary, then we analyzed the residuals of the travel time model. The travel time variation is modeled by ARMA process and the residuals are analyzed by the GARCH model. We proposed to use volatility as one index of travel time reliability and showed the variation of volatility during four years graphically. From that result, we show the characteristics of transition of the index.

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This study aims to find “the effect of different kind of motivational information on different people” in a Mobility Management. After considering the “A measure of the degree of impression” which is for measuring the degree of impression, a web questionnaire survey was conducted. 520 people involved in the survey, and they all live in capital area in Japan and go out by car at least three days of the week.
As a result, it was indicated that people who use a car for a instrumental purpose is easy to be impressed. In addition, the result also show that people who easy to be changed have strong environmental awareness, Social Capital, and subjective well-being, and low in BMI. Also, it is suggested that providing different motivational information for different people can make MM more effective and efficient. For example, the information of “the growth of children” can be gave to a person who has a child, or the information of "health" can be gave to the elderly person.

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Several Real-Time Crash Prediction models have been built as a tool to augment road safety since road traffic crashes are one of the world's largest public health and injury prevention problems. Crashes occurring on freeways/expressways are considered to relate closely to previous traffic conditions occurred before the crash, which are time-varying. Static Bayesian Network (SBN) model has been used in studies previously and Dynamic Bayesian Network (DBN) is a long-established extension to BNs which allow the explicit modeling of changes over time. The assumption behind the model is an event can cause another event in future but not vice-versa. Traffic is a dynamic process and time series traffic data consisting of several time intervals should be used to illustrate this dynamic process of traffic flow before crash occurrence. In this research both SBN and DBN models were built for route 4 Shinjuku Line of Tokyo Metropolitan Expressway. Twenty four DBN and 72 SBN models were built. From the six months data, 71crash and corresponding normal data were used to build the model and randomly chosen 30 crash and corresponding normal data were used for model validation process. After model building and validation, the performances of models build with BN and DBN were compared. The result shows that model built with DBN is able to predict 8.7% more crash conditions than SBN.

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In Hokkaido, as an e fficient improvement that a ffords high-quality service for road users, the intermittent installation of an additional lane to existing two-lane highways (i.e., the creation of 2 +1 lane highways) has been adopted. In this study, the following were targeted as indexes of quality of service for performance evaluation of the road: average traveling speed, follower percent and follower density. Using these indexes, the quality of service achieved by the placement of an additional lane was shown by tra ffic flow simulations and onsite measurements. Two road surface conditions were observed: dry, and compacted snow. Using follower density as an evaluation index, classification of the service level of a two-lane highway in a cold, snowy region was determined. A case study was conducted on the Saraki-Tomanai section of National Highway 40 (between Wakkanai City and Toyotomi Town) in which that section was installed with an additional lane at regular intervals and the following density was measured when the road surface was dry and when it was compacted snow. The measurements demonstrated that the improved road a fforded a service level of A, even when the road surface was compacted snow.

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