This study investigates driving behaviors for mitigating the capacity drop (CD) phenomenon, which means the queuing discharge flow rate is less than the traffic capacity before congestion, at freeway sag and tunnel bottlenecks. Specifically, exploiting a recent advanced continuum traffic flow theory that describes the CD phenomenon endogenously, we first propose two CD-mitigation driving behaviors and discuss their qualitative properties. We next examine the quantitative relationship between the penetration rate of the (autonomous) vehicle implementing each of the proposed driving behavior and the reduction of the queue discharge flow rate through theoretical and simulation analyses. It is then revealed that (i) the prevention of the slow speed recovery due to the sluggish car-following behavior (i.e., the compensation delay for gradient change) at the bottleneck section is essential to mitigate the CD and (ii) the improvement of the acceleration behavior downstream of the bottleneck of only some vehicles has limited impact.

This study focused on the central-lane bus system in Nagoya City, where the road structure near the intersection is often complicated and the risk of accidents may increase. Through the statistical analysis of accident data, the causes of traffic accidents near intersections on the key route bus lane were clarified. In addition, the potential risk of passing vehicles was evaluated from the behavior analysis based on the field survey. As a result, it was shown that there are many jaywalking pedestrians near/at small intersections around 8 o'clock. Next, it was revealed that many dangerous lane changes near stop lines at upstream intersection occur during peak hours between continuous intersections with different lane operations. Furthermore, at a large-scale intersection, risky situations where high decelerations at intersection occur were confirmed despite the high speed of the traveling vehicle in the key route bus lane. In addition, it was clarified that the risk of rear-end collisions at the right turn lane may increase due to the installation of the bus lane.

Currently, almost two-stage crossing facilities introduced in Japan are zebra crossing type. In this study, the applicability of the transverse-type marking of two-stage crossing was examined through analyses using a questionnaire survey and microscopic traffic simulation. First of all, the results of the questionnaire survey revealed that the awareness of traffic rules on transverse-type marking is not high in Japan. Second, the results of the simulation analysis showed that with the current level of awareness of traffic rules on transverse-type marking in Japan, the introduction of the transverse-type marking would have no different impact on traffic than the introduction of the zebra crossing type. On the other hand, when the awareness of the traffic rule of the transverse-type marking increases, the delay time of both vehicles and pedestrians may become smaller than that of the zebra type of two-stage crossing under the condition that the traffic volume of vehicles is low.

In Japan, the number of elderly driver's license holders is increasing with the aging of the population. There are some preferential treatment systems for license returners, and voluntary returners are supported by local governments. The number of voluntary returnees is increasing. Driving cessation among older people is associated with decreased activity, mobility, and exert the risk of functional limitation. The purpose of this study is to analyze the factors that affect the health condition and quality of life of driving cessation among older people, and to consider the maintenance of health after driving cessation. As a result, the driving cessation group has a lower frequency of going out, lower QOL, and less active social activities than license holders. Examining the traffic behavior of the driving cessation group, it was suggested that cyclists and public transport users had higher QOL and active social activities than nonbicycle users and public transport users.

Recently, electric vehicles(EVs) have been introduced, and the charging and discharging control of EVs by using technologies such as V2G (Vehicle-to-Grid) has been considered to avoid the concentration of charging demand of EVs. In this study, the effect of charging and discharging control of EVs in the city-level when EVs are spread was investigated. Specifically, the effect of load leveling of electric power system and reduction of total electric cost and CO₂ reduction by charging and discharging control which minimize the total electric cost was investigated by comparison of several scenarios in Tsukuba city, Ibaraki prefecture. As a results, charging and discharging control of EVs has an effect on load leveling of electric power system, total electric cost and reduction of CO₂ emission. On the other hand, even high carbon tax has imposed, the effect on CO₂ reduction by charging and discharging control of EVs which minimizes total electric cost was limited.

Cities facing the Pacific Ocean have enacted a tsunami evacuation plan to mitigate the damage of the tsunami disaster, from the lesson of the Great East Japan earthquake. However, especially in the center of the cities, evacuees cannot evacuate the nearest evacuation place due to capacity limitations. Thus, it is essential to make local evacuation rules considering local issues beforehand. This study proposes an evacuation plan considering the situation: capacity of evacuation places and evacuation outside the estimated inundation area. The method is that evacuees who cannot reach many evacuation places and outside the estimated inundation area prioritize evacuating closer evacuation places. By applying the local city, it evaluated the effectiveness of the evacuation plan from the aspect of the possible number of evacuees. The result showed that the proposed method could allocate evacuees than present methods. Also, it clarified that evacuating the locations outside the estimated tsunami inundation areas or mountains can improve the total number of evacuees, especially in the regions near the areas.

This study proposed speed adjustment delineators embedded in the center of the travel lane as a preliminary speed adjustment device for drivers who is operating a semi-automated vehicle to reduce conflicts with the merging vehicles on the expressway. We conducted experiments using a VR headset-based driving simulator (VRDS) with 20 participants, and the results of driving records and subjective evaluations showed that the information provided about speed adjustment delineators affected the driver's avoidance behavior. The participants selected the appropriate speed adjustment to follow the speed guide light at the upstream of the nose end in the merging section.This result led to merging behavior smoothly and reduced the subjective risk perceived by the drivers due to the merging vehicles. In addition, the deceleration behavior of drivers when the guide lights on became mild.

In the road project evaluation, cost-benefit analysis is conducted using the daily speed-flow relationship (Q-V), which is uniformly determined according to the road types and number of lanes. However, the existing Q-Vs cannot accurately reflect actual road traffic conditions, and they did not sufficiently take into account regional traffic conditions. In order to fill these research gaps, in this study, Q-V using traffic flow variations and the hourly speedflow relationship (q-v) considering road structure and traffic operations is modeled. The time average travel speed for each time period is calculated by using the traffic flow variations of the actual observed data and q-v. Then, by taking the weighted harmonic mean of these values, the daily average travel speed of a certain daily traffic volume was calculated and Q-V was set. The shape of the Q-V curve can be explained by the traffic flow variations, and the estimated model made it possible to estimate the Q-V considering the actual road and traffic conditions.

Although the number of fatalities in traffic accidents in Japan is decreasing year by year, many people are still injured in traffic accidents. The occurrence of traffic accidents when high school students in Gunma Prefecture go to school is a huge problem. The purpose of this study is to clarify the traffic safety awareness of high school students by analyzing the influence of parent-child relationships on traffic safety awareness in high schools in Gunma prefecture. As a result of analysis using questionnaire survey data for high school students, it was clarified that contact between parents and children at home improves the relationship of trust between parents and children, sympathizes with the beliefs of parents, and has a positive effect on improving awareness of life and traffic safety. According to existing research, the problems that the effect of traffic safety education is small and that the effect does not continue have been raised as issues. This study is showed that efforts including the home environment affect life consciousness including traffic safety consciousness.

The frequent traffic congestions will occur due to the lane restrictions for the reconstruction works in the aging expressways. The zipper merging was proposed at this occasion as merging method to improve traffic condition. In order to establish zipper merging at the lane regulation, it is necessary to provide drivers with appropriate information on zipper merging to reduce the mental load and to improve their awareness of cooperation with zipper merging. In this study, we created a driving simulator that reproduce zipper merging with road signs, and verified changes in the mental and behavior of the drivers in the merging section based on the information content. We obtained the result that the mental load on the drivers was reduced and the cooperation for zipper merging was improved and that zipper merging was expected to be safer and smoother by teaching the actions that should be taken in the driving lane and the actions that would be taken by the drivers in the adjacent lane.

Multiple types of local public transport are implemented in mountainous area. However, it is difficult to sustain local public transport in depopulation phase. As one possibility for sustaining local public transport in mountainous area, it seems that it is important to clarify implementing local public transport enables its-users to go to their desired destination independently, in addition it encourages them to stay living in mountainous area without driving car. This study grasps the reality of "fostering the sense about going outdoors alone" by implementing local public transport for its-users: implementing local public transport enables its-users to go to their desired destination independently. And then, this study clarifies the relationship of "fostering the sense about going outdoors alone" with the frequency of going outdoors and the consciousness of settlement in resident area. As a result, it was clarified the higher "fostering the sense about going outdoors alone" is, the higher the frequency of going outdoors and the consciousness of settlement in resident area are. And then, it is suggested that it is important for fostering the sense about going outdoors independently higher to improve bus shelter and driver's behavior and increase the opportunity of communication for people in local public transport.

Many local governments in Japan are drawing up bicycle network plans and bicycle use promotion plans in accordance with the guideline for bicycle network plans published by the central government, the published revision of the guideline, the Bicycle Use Promotion Act, and cabinet decisions on bicycle use promotion plan in the central government. This study presents a survey of bicycle network plans and bicycle use promotion plans in local governments in Japan. It investigates the number of measures and policies presented in the bicycle network plans and in the bicycle use promotion plans, and also clarifies their details. Additionally, it analyzes how these measures and policies are related to the timing of the creation of the plans. These results are used to perform a further analysis of the extent to which the measures and policies presented in the bicycle use promotion plan in the central government affected the bicycle network plans and the bicycle use promotion plans in local governments.

There is not enough space to mark a bicycle space at a small intersection with a motor vehicle right turn lane because of narrow road width. This study focuses on two-types of bicycle pathway, one is no bicycle lane with separated motor vehicle right turn lane, and another is bicycle lane with no separated motor vehicle right turn lane. These bicycle spaces are referenced in the current version of the intersection design guidebook and the bicycle guideline in Japan. Video surveys were used for evaluating behavior and compliance with bicyclists and motorists. Especially, we observed a proportion of usage for driveway, bicyclists stop position in the intersection, motor vehicle encroachment into the bicycle lane. Comparing two different two types of bicycle space sites, our results indicate that bicyclists incline not to obey rules of stop position at each site. Although the traffic regulation prohibits motorists from entering the bicycle lane besides turning left at the intersection, motor vehicles also tend to enter the bicycle lane in approach to the intersection when they have to keep proceeding straight in the travel lane

The deterioration of the traffic environment around the large-scale retail store becomes a problem because of increasing traffic demand. This study analyzed the traffic problem after the store opening especially by carrying out the continual follow-up survey for the store which faced the community road. According to our analysis, the traffic volume of coming in an hour greatly exceeded the predicted value. In addition, the traffic volume has increased in four years due to the increase of the surrounding population. However, the parking time coefficient per one car was much lower than the guideline value and predicted parking space was enough. In addition, it was clarified that the proportion of coming and going shop route were different on weekday and weekend. Moreover, the thing which passes through the community road which was not supposed in the prediction was continuously observed. Therefore, there is a problem for prior route setting and countermeasure based on it.

In this study, the relationship between the accident factors of "traffic characteristics," "road characteristics", "road environment characteristics" and the risk of human-vehicle accidents was analyzed by accident type based on negative binomial regression models for human-vehicle traffic accidents on non-arterial roads in Chiba Prefecture over a four-year period. As a result, some factors that commonly affect all types of accidents and uncommon factors that have a different impact depending on accident type. Specifically, it was shown that although "un-signalized intersection density" had a positive impact on all accident types, the impact of the "roadside characteristics" factor, which expresses more area-specific activity conditions, was different by accident types. Furthermore, it was shown that the risks of walking along roadway accident and dart-out accident tended to be higher in areas with a high tendency for "central business district type factors". In contrast, the "roadside characteristics" factor was non-significant for accident risk at crosswalks.

Modelling car-following behavior is a promising approach to clarifying mechanisms of capacity bottleneck phenomena in an access-controlled section on an expressway. Since the car-following behavior has nonlinearity, it is possible that deterministic chaos is observed in the behavior. The chaos in the car-following behavior as a microscopic element in traffic flow may relate to a complex phenomenon of traffic flow, such as the stochastic nature of the breakdown. This paper applies chaotic time-series analysis to car-following behavioral data called "Zen Traffic Data (ZTD)" collected on Hanshin Expressway. The analysis estimates the Lyapunov exponent which means the ratio of extension on the attractor in reconstructed phase space derived from the original time-series of car-following data. The positive exponent indicates the chaotic nature in the data. In morning commuting hour (7-8 am), approximately 60% of the following cars have possibly the chaotic characteristics because the Lyapunov exponent of these car-following data are positive. The findings will direct how the car-following is modeled to accurate illustration of the breakdown phenomena in traffic flow on capacity bottlenecks.

KYT (hazard prediction training, K: kiken (a hazard in Japanese), Y: yochi (a prediction in Japanese), T: (training)) is one of the most effective tools in road safety education in Japan. In the past, most of the media used for KYT materials were still images with a third-person perspective. On the other hand, with the recent development of virtual reality (VR) technology, it has become possible to create live-action VR teaching materials with a first-person perspective and 360-degree omnidirectional confirmation. However, the sustainability of the educational effect and the effect on changes in traffic behavior have not been clarified. In this study, we conducted an experiment using the VR and photographic materials created by the authors in a previous study. We conducted a questionnaire survey and analyzed the effects on traffic safety awareness before and after traffic safety KYT and traffic safety awareness and behavior change about two months after the education. The results showed no significant difference in the medium-term educational effect on traffic safety awareness among the teaching materials, including the control group. All the teaching materials affected desired behavioral changes during school commuting.

Fatal crashes between motor vehicle and pedestrian in Japan are caused most by crossing pedestrian-car accidents, and major cause of the crashes is due to pedestrian jaywalking behavior. Therefore, it is necessary to identify the cause of pedestrian jaywalking behavior and to consider control measures. In this study, we analyzed the characteristics of jaywalking crashes on urban roads by using statistical data and analyzed the factors of the crashes by focusing on the location facilities, road structure, and other factors by using GIS. As a result, it was shown that the proportions of jaywalking crashes are more common in young people, in daytime and dusk, and in residential areas, and that bus stops, medical institutions, and convenience stores were cited as roadside facilities near the accident locations. In addition, we clarified the relationship between the width of the roadway and the distance between crosswalks, and the structural characteristics of the boundary of the roadway, and suggested control measures. Based on the results of this analysis, we conducted a questionnaire survey for young people and revealed that the occurrence of jaywalking is affected by the location of crosswalks, signal control, traffic volume, and other factors.

In recent years, measures against traffic congestion by dynamic traffic management have been studied, but the studies on dynamic control of lane use is limited because of the lack of appropriate data. In this paper, we quantify the relationship between lane use and travel time based on vehicle trajectory data collected in the section including the merging section from the ramp. Concretely, the lane utilization ratio of an inner lane and traffic state are aggregated by various time duration and a regression model quantifying the relationship between lane use and traffic state is developed. As a result of parameter estimations with the trajectory data on a freeway section including the lane change prohibited section, it is revealed that i) the travel time can be reduced by increasing the lane utilization ratio of an inner lane under specific traffic conditions, ii) the effects of traffic management vary according to the aggregate time duration, and iii) 60 seconds is generally appropriate as far as the investigation.

When considering regional traffic safety, improving non-signalized intersections with poor visibility is necessary, often found on residential roads in rural cities. However, there is still no common understanding of what indicators should be applied to evaluate the safety of non-signalized intersections. The authors have researched the evaluation of collision risk around intersections using indicators calculated based on road width, driver reaction time, and other factors. However, there were issues with the interpretability of the results and the estimation of damage with collision. This study proposes a new safety evaluation method based on the standard index of traffic conflict, namely PET, in the traffic engineering research fields. As a result of a comparison between the proposed method and the conventional method, it figures out that the conventional method may overestimate the safety. It is possible to understand the vehicle speed that affects the damage in the contact and the collision risk.

It is important to understand the pedestrian traffic volume, which is one of the indicators to quantify the liveliness of the city and tourist attractions. In this study, we quantified the difference between the data obtained by the Wi-Fi packet sensor and the actual pedestrian traffic observed, and investigated the data cleaning method using the signal strength. At four locations in Obuse Town, Nagano Prefecture, pedestrian traffic flow was captured with a video camera and the traffic volume was measured for 15 minutes. A sensitivity analysis was conducted to set the threshold of the signal strength. This made it possible to clean the data according to the environment where the sensor was installed. Then, we performed a regression analysis on the number of pedestrians using the Wi-Fi packet sensor. The results showed that the accuracy of the estimation is sufficient for the case where the increase or decrease of the number of pedestrians is required throughout the year.

The present study proposes a VR headset-based driving simulator (VRDS) as a method to measure drivers' attention allocation when turning right. We will examine whether the VRDS can evaluate the drivers' attention allocation when turning right at a signalized intersection in an urban area. The motion of the right turning vehicle and drivers' eye direction were measured by the VRDS. The results of drivers' eye direction were superimposed on the aerial image recorded from the overhead viewpoint. As a result of experiments with 20 participants using VRDS, the driving scenario that required the driver to look at the gap between on-coming vehicles resulted in more complications with pedestrians when turning right. In addition, a pedestrian from the right turned into the blind spot of the A-pillar, resulting in a collision. Based on these findings, VRDS might be contributed to develop an interface that informs the presence of pedestrians at an appropriate time, which the drivers tend to overlook.

In recent years, pedestrian circulation has become a major theme as station and town spaces are being modified by the insertion of new transportation modes. However, the existing models assume the same travel time between all intersections and do not correctly evaluate the reduction of future value, and do not correctly evaluate the sequential decision making that is characteristic of pedestrian migration. The future value reduction is not properly evaluated. In this study, we formulated a recursive migration model with a generalized time discount rate for link length that can be applied to networks with different link lengths, and verified the validity of the model and the transferability of parameters by conducting parameter estimation and validation comparisons for eight station networks. The model is validated by parameter estimation and validation comparison in eight station networks, and its superiority is demonstrated by comparing its likelihood with that of a conventional model.

In this study, we installed vision-based driver monitoring sensors to older drivers' private vehicles for measuring their driving behavior (e.g. scanning behavior, vehicle speed control, etc.) in real traffic environment in their daily life, and collected large-scale driving behavior data for 737 days, 14,233 kilo meters in total. Since the most frequent traffic accident pattern by older drivers is broadside collision, we focused on stop-controlled intersections and analyzed older drivers' behavior from the viewpoint of active safety. As a result of our analysis, we found out that 22.8% of all cases of driving straight through an intersection, older drivers insufficiently performed scanning behavior to the both sides of the intersection for checking safety. We also found out that 46.8% of all cases of turning right/left an intersection, older drivers performed scanning behavior only to the one side of the intersection, which could lead to increase collision risks to other vehicles, cyclists, and pedestrians.

The turning ratio and the traffic demands of each direction at signalized intersections are important to optimize the traffic signal control. While these values can be observed by using traffic detectors for each direction, the cost for installation and maintenance becomes high. Recently, probe vehicle data is available, which can be used to observe the turning ratio. However, if its penetration rate is low and the aggregation time duration is short, the accuracy of the estimation becomes low. In this study, we developed the dynamic estimation method of turning ratio and traffic demands by direction based on the Sequential Bayes Inference, in which both probe data and traffic detector data are jointly used. The proposed methods were applied to some signalized intersection in which traffic volumes of all directions were manually counted by every ten minutes. As a results, it is shown that the proposed methods can accurately estimate the traffic volume of each direction even in the case that the penetration rate of probe vehicles is 2 % and that the traffic detectors are limitedly installed on the major directions.

This study develops a spatial economic analysis method that can evaluate the impact of transportation infrastructure development and technological innovation on population distribution and regional economy by extending the analytical framework in the field of Quantitative Spatial Economics (QSE). Based on the findings of Takayama and Sugiyama¹⁾, we develop a QSE model that is able to appropriately represent the transportation network reflecting the convenience of not only automobiles but also public transportation systems such as railways, airlines and express buses. We then present a method for setting the parameters of this framework, along with the necessary data sets. In addition, we study the impact of interregional transportation improvements on population distribution in Japan. The results show that the changes in population distribution are qualitatively different depending on the transportation mode that decreases the transportation cost (e.g., population concentration in the three major metropolitan areas and population dispersion in regional areas).

The occurrence of traffic accidents in Japan has continued to decrease, but the road traffic environment is expected to change rapidly in the future with the development of next-generation transportation. In this context, there have been many moves in recent years in various fields to use AI (artificial intelligence) to analyze big data and predict events that have been difficult to predict using conventional methods. In the field of traffic safety, the Metropolitan Police Department is also using AI to predict the occurrence of traffic accidents in order to implement effective traffic enforcement activities. In this study, we developed a model that predicts the optimal location for traffic enforcement activities by using Q-Learning, a type of AI. Furthermore, by quantitatively evaluating the deterrent effect of traffic accidents caused by the traffic enforcement activities based on the prediction results, we can obtained knowledge on how to effectively implement enforcement activities in the future.

This study investigates the causes of the decline in the number of bus users during COVID-19 using integrated circuit (IC) card data of the Toyota City Oiden Bus. The number of bus users in April and May 2020 and February and March 2021 were investigated based on the population characteristics and layout of the facilities at bus stops. The results indicated that in February and March 2021, the number of bus users on holidays and travelling long distances was low. In addition, the number of bus trips to cultural facilities could be low. This suggests that people are refraining from using the bus for nonessential purposes. A short-term plan is necessary to meet the demand for short-distance travel. A long-term plan to restore bus usage to that in the pre-COVID era is also necessary to improve the city's liveliness and quality of life.

This study proposes a short-term prediction method of traffic congestion using ETC2.0 probe data for traffic congestion in a tourist area, which is considered to be highly variable and difficult to predict. Since the demand for tourism in Japan has been increasing steadily, traffic congestion in the vicinity of tourist attractions has become more serious and desired to be improved. In this study, the state-space model was used to predict the travel speed in 500-meter increments and the travel time of the entire section after one hour for the Hakone area of Route 1. In the modeling, after considering various combinations of exogenous variables, the holiday flag and the number of tweets as an indicator to indirectly express the degree of tourism demand are adopted. As a result, it was found that the state-space model was able to predict the speed decrease especially during peak hours.

While bus routes that allow passengers to reach their destinations without transfers to another route are convenient, such routes result in duplication of the routes. In order to form an efficient bus network, it is essential to set up routes based on the premise of transfers. However, transfer can also be inconvenient for passengers. Therefore, it is necessary to grasp the actual transfer situation and clarify the influence factors on transfers. In this study, we captured the actual transfer situations based on OD data of a community-bus including transfer. Furthermore, we clarified the relationship between transfer behavior and the temporal features such as the difference in time required for the OD travel, and waiting time for transfer, as well as the spatial location of transfer bus stops. As a result, it is found that the ratio of detour to the transfer location and the difference between the distance from the origin to the transfer location and the distance from the transfer location to the destination influence on the number of the transfer locations.

According to the traffic accident statistics in Japan, the accident rate for expressway is around 10 times lower than that for ordinary road. Therefore, analysis of driver's attitudes toward driving on the expressways is essential in order to examine effective traffic accident risk communication intended to enhance the expressway usage. This study investigated the driver's cognitive structure toward expressway usage focusing on the attitudes toward the traffic accident using a large-scale web-based questionnaire survey of daily drivers. The results showed that the fear of driving on the expressway had a dominant impact on the intention of its usage. Also shown was that many drivers who refuse the expressway usage tend to overestimate its accident risk, and are more likely to have a fear of what might happen on the expressway. Furthermore, while they are highly aware that whether or not an accident occurs depends on their own driving, they tend to lack confidence in their driving on the expressway.

As for the safety of bicycle traffic environment, it is desirable for bicycles to travel in the same direction as automobiles on the roadway because it is considered that the difficulty for car drives to recognize bicycles outside the roadway is a cause of accidents, and the development of a travel space based on traffic on the roadway is being promoted. In this study, video surveys were conducted at several signalized intersections with different intersection inflow conditions for bicycles and left-turning vehicles, and trajectory data from the faster Regions with Convolutional Neural Network Method (Faster R-CNN) was used to investigate the complex phenomenon of straight-line bicycles and left-turning vehicles. For the evaluation method, we focused on the change in speed during the time of conflict and used the quasi time-to-collision (TTC) and the speed difference through the intersection. As a result, it was found that while the speed of bicycles did not change much between different sections of the road, the presence or absence of complications and the position of the traffic were major factors in determining the speed.

Route buses, which are familiar public transportation to people, should be easy to use for everyone. However many bus users often get on a bus with psychological resistance because basic information on bus usage is not always very clearly announced to them in Japan. In this study, therefore, we focused on bus route maps and clarified the effect of the number of bus stops, font size, and other components of bus route maps on bus user understandability.

We created 8 patterns of original bus route maps and conducted experiments in which subjects searched for a bus route. The results show that the most influential factor in the understandability is the number of bus stops, follows by the size of the text. Further, we found that it is desirable to create area version maps for easy to understand bus routes if there are more than 86 bus stops on the map.

This paper describes a study involving a constant-speed run survey by plural drivers at an S-shaped expressway curve section where accidents have frequently occurred. The right-turn curve that is the first half of the section successively comprises the first clothoid curve, the first circular curve, the second clothoid curve, and the second circular curve. We estimated each run to fall into an understeering state because the lateral acceleration did not increase despite an increase in steering angles from the end of the first circular curve. Those observations matched the run trajectories estimated by the GPS positioning, likely caused by the discontinuous re-increase in curvature at the end. Based on video data framed by plural cameras, we estimated run trajectories of unspecified vehicles’ lateral acceleration of a run at 125 km/h to reach around 2.5 m/s². The lateral acceleration was close to an upper limit on wet road surfaces, potentially resulting in uncontrollable situations when combined with the understeering states.

In this study, we tried to clarify the factors of speed reduction in non-congested condition and factors that can determine whether or not deceleration waves occur when speed reduction occurs in non-congested condition, targeting areas with frequent congestion on urban expressways. Using continuous trajectory data, we drew contour diagrams and compared the relationship between traffic characteristics and velocity. At the same time, we defined variables related to vehicle platoon characteristics using Time Tailaway and Inter-Vehicular Distance. We also defined deceleration wave states. Next, speed reduction factors were verified by multiple regression analysis, and deceleration waves generation factors were verified by discriminant analysis, considering the time lag.

As a result, it is suggested that left lane utilization ratio increases due to the increase in traffic volume, and when the increase reaches a plateau, speed reduction occurs. At the same time, “Short Time Tailaway Vehicle Ratio” become small and “Short Inter-Vehicular Distance Vehicle Ratio” increases. It is also suggested that the factors that can determine the occurrence of deceleration waves include traffic volume, lane utilization, vehicle platoon characteristics, and lane-changings with large conflicts.

The authors have been conducting research on the application of "verbal maps" that replace visual information with auditory information. In recent years, we have been trying to create a " Sightseeing Verbal Maps " for visually impaired people to enjoy walking to improve their quality of life (QOL). This time, we chose Itami Sky Park and the approach to Kiyomizu Temple Road as the target areas, and we created a map of sightseeing spots by incorporating guideposts, environmental sounds, and sound effects that are closer to reality and motivate people to go out. In addition, due to the influence of the Corona disaster, virtual walking experiments and interviews for the visually impaired, which had been conducted in the laboratory, were conducted online using the teleconference tool Zoom. Through the interviews, we were able to improve the word map, clarify useful environmental sounds and sound effects, and examine the feasibility of the online environment.

The widespread use of automated vehicles is expected to have positive effects on safety and traffic facilitation. The widespread use of automated vehicles will have an impact on the location and total number of parking spaces. The location of parking lots will be freed up due to changes in usage, and the demand for parking lots will decrease due to the spread of vehicle sharing. The purpose of this study is to quantify the impact of the spread of automated vehicle sharing services on the location and total number of parking spaces. This is a simulation of the matching of ridesharing and the addition of access/egress trips to parking lots for each sharing service diffusion scenario and examined the degree of parking lot consolidation appropriate for each scenario from environmental, economic, and social perspectives. As a result, it was found that the more widespread the sharing service becomes, the more desirable it is to consolidate parking spaces on a large scale.