Takashi Oguchi

• PhD
• Professor at The University of Tokyo

This open access book gives comprehensive empirical insights on connected and automated driving (CAD) of road transport vehicles which leads to the driver being partially or completely replaced by automation. The current trend towards widespread research and development of automation of motorised individual transport is driven by the expected benef...

The chapter “ Setting the Scene for Automated Mobility: A Comparative Introduction to the Mobility Systems in Germany and Japan ” provides an overview of the framework conditions characterizing the transport systems in Germany and Japan. Following two chapters investigate relation of the governance style to regulatory changes and resource allocatio...

ACC 利用者を対象とした WEB アンケート調査を実施し、ACC 機能の利用実態や、ACC に対する意識の経年的な変化を分析した。 分析の結果、現時点における高速道路利用者の ACC 装着率は概ね 3 割程度と想定できること、個人 の経年変化として ACC 利用頻度は増加している状況であり、 交通状況によって ACC 利用頻度や設定車 間距離を変化させていることを明らかにした。また、自身の運転と比べて速度は低く、車間距離は長く なっているという傾向にあり、ACC の普及が近年の交通性能低下要因の 1 つである可能性を考察した。 その他、ACC とは関係なしに、加齢に伴い交通性能を低下させる方向に運転挙動が変化していることを 明らかにし、高齢ドライバーの割合の増加も交通性能低下要因であること...

The popularization of electric vehicles (EVs) is limited by their driving range and long charging times. To address this, in-motion wireless power transfer systems (WPTSs) are currently attracting attention as a new power supply system. In-motion WPTSs have coils embedded under the road to transfer power from the WPTSs to EVs while driving. However...

The facilities which serve as local hubs and are attractive enough to be visited as destinations are expected to be assessed from various perspectives. In this study, we propose a method to evaluate the value of facilities themselves, by estimating their utility values to generate visits and their consumer surplus based on the travel cost spent to...

Previous studies have shown that the traffic performance of interurban expressways declined during the past 14 years from 2003 to 2016. However, it is not clear how it decreased during the same period. In addition, there are few studies showing the secular change of the observed non-congested speed by traffic volume, and the change in speed distrib...

This paper proposes a macroscopic model to describe the equilibrium distribution of passenger arrivals for the morning commute problem in a congested urban rail transit system. We use a macroscopic train operation sub-model developed by Seo, Wada, and Fukuda (2017, 2022) to express the interaction between the dynamics of passengers and trains in a...

The novel coronavirus epidemic has had a major effect on transportation. In this chapter, the future of post-pandemic transportation is discussed and measures for its improvement are proposed, based on the pre-pandemic transportation problems and the changes that have occurred due to the pandemic in Japan. In the post-pandemic world, demand levelin...

The location analysis based on mixed-integer programming has been actively discussed mainly in the fields of geography and operations research. In this study, we show Multi-objective optimization of “Michi-no-Eki” Locations in the greater Kanto area considering various users and functions. Especially we consider not only differences between local d...

A previous study has shown that traffic capacity and operational performance of expressways declined from 2003 to 2016. However, they did not explain why this phenomenon occurred. Besides, no previous studies have showed the secular change of both observed breakdown flow rate and queue discharge flow rate. In this study, after analyzing the traffic...

Published in JSTE Journal of Traffic Engineering (in Japanese). The “capacity drop (CD)” phenomenon, which means the queue discharge flow rate is less than the traffic capacity before congestion, is observed at freeway bottlenecks in general. Although this phenomenon has been known for a long time, its precise mechanism is not necessarily clear. T...

Origin-Destination (OD) traffic volume data are expected to improve the performance of traffic simulators by providing more precise demand input, which can support efficient traffic management and operation. This study analyzed the temporal fluctuation of OD traffic volume in the whole Tokyo metropolitan expressway network using electronic toll col...

In signal control, which is one of the main functions of traffic control systems, appropriate signal control parameters are calculated based on the measurement data from vehicle detectors installed on the road. However, the installation and maintenance of vehicle detectors is costly, so realization of a signal control system that can reduce the num...

Shared autonomous vehicles (SAVs) can have significant impacts on the transport system and land use by replacing private vehicles. Sharing vehicles without drivers is expected to reduce parking demand, and as a side effect, increase congestion owing to the empty fleets made by SAVs picking up travelers and relocating. Although the impact may not be...

Origin-Destination (OD) traffic volume data are expected to improve the performance of traffic simulators by providing more precise demand input, which can support efficient traffic management and operation. This study analyzed the temporal fluctuation of OD traffic volume in the whole Tokyo metropolitan expressway network using electronic toll col...

At large-scale events such as the Olympics and Paralympics, it is important to guide people such as evacuation guidance in the event of crowded accidents, earthquakes or terrorism. In Japan, there are problems of guiding pedestrians, such as the walking direction of pedestrians is different depending on the locations and facilities. Globally, the p...

Violations, risky behaviors and perceptions may largely contribute to crashes involving pedestrians, particularly at unmarked mid-block locations. The likelihood and severity of crashes at mid-block locations are higher compared to intersections. This study explores pedestrians’ behaviors at and perceptions about unmarked mid-block locations. The d...

This study explores the performance of an alternative crosswalk design, where crosswalks are removed from the intersections and placed at nearby mid-block to reduce conflicts between turning vehicles and pedestrians. Several scenarios with balanced and unbalanced vehicle volumes were considered to represent a range of practical vehicle demand level...

Shared autonomous vehicles (SAVs) can have significant impacts on the transport system and land use by replacing private vehicles. Sharing vehicles without drivers is expected to reduce parking demand, and as a side effect, increase congestion owing to the empty fleets made by SAVs picking up travelers and relocating. Although the impact may not be...

This paper proposes a macroscopic model to describe the equilibrium distribution of passenger arrivals for the morning commute problem in a congested urban rail transit system. We employ a macroscopic train operation sub-model developed by Seo et al. (2017a,b) to express the interaction between dynamics of passengers and trains in a simplified mann...

Information on the trajectories of turning vehicles at signalized intersections can be used in numerous applications, such as movement planning of autonomous vehicles, realistic representation of surrounding vehicle movements in driving simulator and virtual reality applications, and in microscopic simulation tools. However, no proper framework is...

Origin-destination ( OD) traffic volume represents an important parameter of traffic demand, when considering more efficient traffic management strategies on expressway network. In this study, we analyzed temporal fluctuation of OD traffic volume in the whole Tokyo metropolitan expressway network, using the ETC data which is recorded by electronic...

This study conducts an empirical analysis of the capacity drop phenomenon at sag bottlenecks based on the recent advanced continuum traffic flow theory. We first show the underlying phenomena, components, and consequences of the theory in a concise manner. We then compare several theoretical predictions with real data, qualitatively and quantitativ...

This study evaluates the performance of an alternative crosswalk design for critical intersections. A critical intersection is a busy intersection in a network which limits the capacity of the network and the congestion effects due to such an intersection may spread throughout the network. Besides vehicular traffic, pedestrian traffic also affects...

Prediction is an important part of the traffic management system (TMS) which supports route planning, dynamic traffic control, and information provision. We developed a multi-dimensional learning machine for predicting the traffic speed. Proposed methodology considered both historical experience and near past observation of traffic data by combinin...

This paper presents a novel modeling approach for estimating trajectories (i.e., paths, speed, and acceleration profiles) of left and right turning vehicles at signalized intersections. The modeling method is based on the minimum jerk concept which has initially been applied in neuroscience and robotics domains. The suitability of the modeling conc...

This study explores unobservable factors which describe pedestrian mid-block crossing behavior. A mid-block is a location away from intersections where pedestrians cross in the absence of a crosswalk. An online questionnaire was developed that included 24 (5-point Likert type) items about pedestrian behaviors, mobility patterns, preferences, percep...

The gridlock phenomenon in this study is defined as a condition in which a traffic queue forms all around a single grid (rectangular shape) road network and it causes a capacity reduction of the network without external intervention by the influence of downstream traffic queue on the throughput of an intersection of the network. When an isotopic co...

Wi-Fi detector has received much attention for travel time observation of four-wheelers, two-wheelers, and pedestrians in the recent decades. The data cleaning method is one of the essential comportments to derive travel time from Wi-Fi detection because Wi-Fi scanner is not originally designed for the travel information observation. The aim of thi...

Wi-Fi detector has received much attention for travel time observation of four-wheelers, two-wheelers, and pedestrians in the recent decades. The data cleaning method is one of the essential comportments to derive travel time from Wi-Fi detection because Wi-Fi scanner is not originally designed for the travel information observation. The aim of thi...

Efficient detection and analysis of natural sinkholes is essential for human sustainability in karst area. In this work, two methodologies were applied to detect and quantify natural sinkholes in southwest China, using of DEMs derived from ASTER and SRTM remote sensing images and topographic maps. The methodologies were a semi-automatic approach an...

When a traffic queue forms all around a single grid road network and it causes a capacity reduction of the network (gridlock phenomenon), measures to relieve the gridlock phenomenon and recover the reduced capacity by controlling the road infrastructure are discussed in this paper. Controlling the road infrastructure is to adjust the merging ratio...

Speed profiles can be considered as a key input for assessing safety, comfort and efficiency of highway or expressway segments. Therefore, understanding drivers’ speeding behavior, particularly on expressway curve sections, is important. Most previous studies have modeled the speed on highway curve sections mainly as constant or a piecewise linear...

It is necessary to conduct the traffic operation policy using intelligent transportation systems technologies, if road network will be used effectively under implementing the expressway’s network. On the other hand, it is necessary to evaluate the effective and safety of this policy in advance using virtual traffic experimental environment such as...

Speed profiles can be considered as a key input for assessing safety, comfort and efficiency of highway or expressway segments (i.e., highway design consistency evaluation in broad sense). Most previous studies have modeled the speed on highway curve sections mainly as constant or a piecewise linear profiles. Such approaches may not realistically r...

Freight vehicles are used differently depending on the vehicle type and trip length, such as small-sized trucks used for shipping and large-sized trucks used for trunk transportation. Furthermore, since the route choice behavior of a freight vehicle is subject to the restriction by the size of the vehicle, it can not be ignored that a difference oc...

A development of large-scale traffic simulation for the Tokyo Metropolitan road network to estimate the road network traffic flow dynamically, especially after the mostly completion of three expressway rings, named “Chuo ring”, “Outer ring” and “Ken-o ring”, is outlined. The development is aimed at the evaluation of various policies; including traf...

Microscopic simulation is used for safety evaluation of the interactions between turning vehicles and pedestrians/cyclists at signalized intersections. For reliability, the employed models should realistically capture the vehicle turning trajectory. Previous studies considered the vehicle path and speed using different models. However, this may not...

This research focuses on the applicability of the FIFO assumption to describe congregative vehicle drop-by behavior in order to understand the congregative performance of an expressway parking area, with using both the results of a field survey and the data of vehicles entering and exiting a parking area collected by ETC probe timestamps. The resul...

The inter-driver variability of follow-the-leader behavior is well recognized as a main cause of bottleneck phenomenon on expressway basic segment. The bottleneck phenomenon observed at sag sections on Japanese expressways is an example where the accumulation of driving behavior variability results in obvious capacity drop and probabilistically occ...

This paper proposes an approximation method of expected delay for signalized arterial roads under stochastic arrivals. This method is based on variational theory of traffic flow (VT). In VT under stochastic arrivals, traffic flow dynamics is described as the solution of the stochastic shortest path problem in the network on a space-time domain, whi...

A development of large-scale traffic simulation for the Tokyo Metropolitan road network to estimate the road network traffic flow dynamically, especially after the mostly completion of three expressway rings, named "Chuo ring", "Outer ring", and "Ken-o ring", is outlined. The development is aimed at the evaluation of various policies; including tra...

Accurate assessment of soil loss caused by rainfall is essential for natural and agricultural resources management. Soil erosion directly affects the environment and human sustainability. In this work, the empirical and contemporary model of revised universal soil loss equation (RUSLE) was applied for simulating the soil erosion rate in a karst cat...

For the reasons of environmental issues, congestion mitigation, and vulnerable road users, the surface mass public transport (PT) system in urban area should be improved and promoted in Japan. This paper provides an overview of the current state of public transport priority system (PTPS) and the possibility of advanced PTPS. The effects of advanced...

The midblock crosswalks can improve pedestrians’ accessibility while may decrease vehicle flow performance in arterials with the dense signalized intersections in an urban area. This study compares the effectiveness of different midblock crosswalk treatments in urban areas where nearby traffic signals are coordinated. Signalized single stage and tw...

The function of parking areas at expressway rest stops is to provide drivers with opportunities to park their vehicles for their own purposes, so the number of parking spots has been discussed. However, as the number of parking spots increases, the parking area becomes maze-like and the use of the parking spots becomes inefficient. This leads to sk...

Understanding free-flow speed and its variance is important to evaluate the safety and performance of expressways. Not only the geometric factors considering directly in geometric element design criteria, but also other factors which are not explicitly considered (for ex., number of lanes, width of lanes, center median etc.) affect the variation of...

Conflicts between left-turning vehicles and road crossing pedestrians or cyclists is one major safety issue at signalized intersections. Simulation based as well as non-simulation based conflict analysis methods can be utilized to explore the characteristics of these conflicts such as time to collision, collision point and speed. Existing microscop...

Conflicts between left-turning vehicles and road crossing pedestrians or cyclists is one major safety issue at signalized intersections. Simulation based as well as non-simulation based conflict analysis methods can be utilized to explore the characteristics of these conflicts such as time to collision, collision point and speed. Existing microscop...

Traffic flow rates are not fixed but changed as a probabilistic nature when the traffic congestion occurred at the ordinary bottleneck section like sag sections on Japanese expressways. The probabilistic nature is believed as mainly because of the difference of driving behavior. Data at Yamato-sag section on the westbound of Tomei expressway are ac...

Japan has experienced an enormous increase of traffic accidents as a result of the country's rapid economic growth from the late 1950s to the year 1970. Observers in the early 1960s called the proliferation of traffic accidents the “Traffic War” as the annual traffic-accident fatalities exceeded the average annual fatalities during the First Sino-J...

The objective of this study is to empirically analyze and model the stop-go decision behavior of drivers at rural high-speed intersections in China, where a flashing green signal of 3s followed by a yellow signal of 3s is commonly applied to end a green phase. 1, 186 high-resolution vehicle trajectories were collected at four typical high-speed int...

This research is focused on emergency transport of ambulance. Because, future population of Japan is different from now. The purpose of the research is formulation of a forecast of demand for emergency life-saving transfer. And we were validated the model on case study at Matsuyama-city. As a result of the validation, we was ascertained with high a...

The objective of this study is to investigate the use of DEMs derived from ASTER and SRTM remote sensing images and topographic maps to detect and quantify natural sinkholes in a karst area in Zhijin county, southwest China. Two methodologies were implemented. The first is a semi-automatic approach which stepwise identifies the depression using DEM...

A sag section is a road segment on an expressway in which the vertical slope increases at a small but constant rate. Sag sections are the main traffic bottlenecks on Japanese expressways. Variations in individual car-following behavior are generally recognized as the key cause of traffic breakdown. This research was conducted to develop a quantitat...

Emergency transportation service can take emergency patients to hospitals, which is one of the most important governmental services. Now in Japan, the population is decreases and the demand of the calls for ambulance is predicted to increase. Therefore, it is requested that we make the service as efficient as possible and we have an appropriate sch...

For reducing CO2 emission from road traffic, we constructed a social system to make regional citizens aware of CO2 emissions and to promote their eco-friendly travel behavior. First, regional traffic situations are discretely observed through monitoring cameras and probe information, and the whole situation in the region is estimated by interpolati...

One limitation of point-based detectors is their inability to estimate directional demand （i.e. number of leftturners, through, and right-turners） at intersections. This affects traffic signal systems that have separate rightturn phases. Right-turners often experience significantly longer waiting times due to short green-time allocations despite lo...

This study aims to develop car following models which simulate various adaptive cruise control (ACC) behaviors for a microscopic traffic simulator. There is a need for a microscopic traffic simulator to evaluate the impact of ACC penetration on highway traffic conditions. If the method of modeling of the simulator follows ACC technology as it is in...

This paper describes the development of an on-line traffic simulation system called the “Nowcast Traffic Simulation System” for road traffic in urban areas. The system can reproduce the traffic situation based on various types of traffic data provided in real time such as floating car data and traffic sensor data. The output data is used for severa...

It is important to prevent occurrence of gridlock phenomenon because it may cause greatly decreasing the network capacity and rapidly expanding the traffic congestion to a large area. However, the mechanism which gives rise to gridlock phenomenon on urban street network is so complicated and still remains major challenge. The occurrence condition o...

Eco-driving is well known as an environmental program against the emission of CO2 in the field of automobile. As the relation between kinematics and energy consumption of gasoline-powered automobile has been discussed not only theoretically but also demonstrably, it has not been discussed much about that of electric vehicle which is becoming more a...

Drivers commonly depend on information obtained from road signs and traffic signals for guidance. Nobel assistance systems have been taking place in recent years. In the effort to develop more effective safety measures, it is important to evaluate these measures objectively. A driving simulator named as mixed-reality traffic experiment space has be...

In this study, we formulate a methodology for estimating turning rates at an intersection under oversaturated traffic conditions. Turning rate information can contribute to the improvement of signal control parameters and correct delay estimation. Detector and probe data from Infrared beacons are used with a traffic simulator to reproduce average p...

The analyses of route choice behavior based on revealed preference (RP) data are rare because of the difficulty of observing route choice decisions in practice. On Tokyo metropolitan expressway, traffic surveillance and electronic toll collection (ETC) systems provide rich sources of traffic condition and behavior data. This paper analyzes route ch...

The study is to improve the preliminary evaluation of effectiveness of road-traffic safety countermeasure for reformation plan of an actual intersection on National Route 16 in Kashiwa City, Toyofuta Kogyo Danchi Iriguchi Intersection, where traffic accidents of rear-end collision often occur. Utilizing national digital map, traffic scenario for dr...

The traffic flow at approaches to signalized intersections is determined by a multitude of factors. This results in randomness in the parameters that have to be estimated in order to calculate the signal change intervals. If factors influencing the distribution of these parameters can be identified, less safety margins may be feasible. In this way...

Interval between the end of the green time for one traffic stream and the beginning of the green time for the next traffi c stream is known as the signal change interval. The signal change interval consists of the yellow and all red time to avoid potential accidents among various confl ict movements. The design of signal change intervals between tw...

Street pattern in Tokyo has been transformed along with being affected by some important historical events. In this study, we take four events as important turning points, which are the Meiji Restoration, the Great Kanto Earthquake of 1923, World War II, and rapid economic growth. As a methodology, we use Axial Analysis of Space Syntax theory. Axia...

Route choice analysis based on revealed preference (RP) data plays an important role in various applications on urban expressway. Yet, the exact route choice information is difficult and expensive to be obtained in practice. Conversely, the availability of traffic surveillance systems and electronic toll collection (ETC) system opens possibility to...

Chuo Expressway is one of the main arterial expressways connecting between Tokyo and Nagoya through some resort areas and mountainous areas, so the traffic volume on the expressway reaches to 100,000 per day on holiday and weekends. The traffic congestions, which have more than 30km length, occur frequently under the heavy traffic volume. As a meas...

Quality of road traffi c in Japan is still unsatisfactory as the road network cannot achieve the desirable performance corresponding to traffi c and access functions of roads yet, and there remain a lot of subjects to be resolved in terms of road design and traffi c operations. The existing road network should be gradually improved and restructured...

In this paper, an integrated speed-estimation model is developed based on empirical analyses for the basic sections of intercity multilane expressway un der the uncongested condition. This model enables a speed estimation for each lane at any site under arb itrary highway-alignment, traffic (traffic flow and truck percentage), and rainfall conditio...

The highway traffic congestion is one of the most important social and technical issues from the early days of motorization in Japan. Accordingly, the highway capacity has long been a major concern of traffic engineers, not only in research but also in practice, in order to alleviate the traffic congestions. Also, the concept of the quality of serv...

This study analyzes the effects of renewal of vehicles in Tokyu Setagaya Line on the promotion of use by the questionnaire surveys. The result shows that promotion effects and image-up effects are strongly influenced by a physical improvement and change in the design. On the other hand, there is possibility that they are influenced by the evaluatio...

Redesigning of the traffic system on highways, streets and avenues is quite important, when aspects such as network plan, geometric design, traffic control, operation, regulation and enforcement of roads are considered as a unified system. The ‘highways’, which should primarily consider transport function for intercity connections, and ‘streets and...

This study evaluates legibility of graphical information boards on the expressway, which is typical road map with colorful traffic information, focusing on the graphical characteristics of a road network in the graphical information board. The factors to affect the legibility were extracted in the viewpoint of “map information” and “easiness of rou...