This study investigates the dynamic journey time estimation (DJTE) problem, which can be used to simultaneously estimate the mean and standard deviation (SD) of path journey times in stochastic road networks. A bi-level programming model is proposed to solve the DJTE problem. The upper level is used to minimise the deviations of the mean and SD between the estimated and observed path journey times. The lower level is a reliability-based dynamic traffic assignment model taking into account the variation of path journey times. The modified simulated annealing (SA) algorithm is adapted to solve the proposed bi-level problem. A numerical example is used to illustrate the application of the proposed DJTE model and the modified algorithm together with insightful findings.
Normally, under unbalanced traffic volumes, roundabout metering that operates with traffic signals on one (sub-dominant) approach is used to improve roundabout operating conditions. There are few reports of studies concerning roundabout metering that operates with traffic signals on two approaches. SIDRA INTERSECTION 6 is a widely used intersection evaluation software with a roundabout metering model which allows only one approach to be signalized. This paper reports a study of roundabout metering with signals on two approaches using a SIDRA INTERSECTION 6 network model, representing the roundabout as a four-node network. The model is applied to a real-life case on Old Belair Road in Adelaide for the morning peak period (08:00-09:00 AM). Calibration methods are suggested for this analysis. The results of the analysis indicate that the level of service (LOS) and the delay time on the dominant approach are C and 23.2 seconds.
This study proposes a flow-rain-dependent algorithm for the automatic detection of traffic incidents under both rain and no-rain conditions. To overcome the shortcomings of discrete detection thresholds in previous automatic incident detection (AID) algorithms, continuous detection thresholds are used. These thresholds are generated by calibrated generalized detection threshold functions, in which both pre-incident traffic and conditions in rain are explicitly modeled. The volume/capacity ratio, which can better describe the degree of congestion, is used to indicate the pre-incident traffic conditions in the proposed algorithm. A case study is carried out on a territory-wide road network in Hong Kong to demonstrate the performance of the proposed AID algorithm. Traffic data for journey time estimation is collected from the Hong Kong urban road network. The results show that incorporating the rain effect when determining the detection threshold can improve the overall performance of traffic incident detection.
Besides circulating flow, pedestrian flow is another key conflict stream that significantly influences roundabout entry capacity. Due to limited space in Japan, several standard designs such as a physical splitter island cannot always be installed at the roundabout entry/exit. The impact of several influencing factors on entry capacity such as splitter islands was examined by applying a microscopic simulation to our previous research. A regression model was proposed based on the simulation results, which assumed that vehicles yielded to all pedestrians at the beginning of the crosswalk. In this paper, the regression model was validated using field data observed in Japan. The regression model was improved by adding a parameter to reflect drivers’ compliance with pedestrians. The validation results indicate that the improved model shows good fitness to the field data and the results imply that roundabout geometry and traffic flow composition significantly influence entry capacity.
This paper proposes a system partition model to improve the signal coordination control in large-scale urban arterials based on the classical MAXBAND methodology. The model divides the arterial system into several subsystems. Signal coordination is performed in each subsystem by considering the demand distribution along the whole arterial system. The obtained model is a mixed-integer nonlinear programming problem with multiple sets of binary variables. Numerical examples on an arterial of 20 signalized intersections show that the proposed model has potential to produce coordination plans that outperform those generated by Synchro.
Motorcycles are one of the main transportation modes in some Asian countries because of their advantages, such as better mobility and lower costs, compared with automobiles. Most of the current road designs, such as speed limits and lane markings, are based on automobile traffic and are not entirely suitable for motorcycles. Therefore, there is a need to investigate further the traffic characteristics of mixed traffic flows and vehicle interactions where the proportion of motorcycles is high. With a proposed novel data-collection approach using aerial videography, a detailed and accurate vehicle trajectory dataset for a traffic stream in an urban arterial system was collected. The mixed traffic characteristics such as lane choice, lateral position distribution, and spacing distributions at various levels of traffic density were investigated. These characteristics could be useful for the development of microscopic behavioral models and integration with traffic simulation models for the evaluation of a mixed traffic environment.
This study aims to identify influencing factors of traffic accidents on Japanese major roads through factor analysis and regression analysis for each accident type, considering their characteristics as rare events. The database consists of a five-year accident record and relevant road traffic condition data on major road sections in Aichi Prefecture, which includes the third largest conurbation area of Japan. From the results of the factor analysis, a trend of high accident rates in broad urban arterials is confirmed, and rear-end or side collisions are widely distributed in suburban areas. From the regression analysis, results reveal that the degree of impact by traffic volume is dependent on accident type, and suggests that several factors related to visibility have an influence on turning and side collisions. The study suggests that improving the quality of traffic flow on major roads by ensuring proper intersection spacing is important for establishing a safer road network.
This study focuses on the development of a driving risk model based on speed deviation. Speed data were collected via an on-site driving experiment on the Sanyo Expressway in Hiroshima Prefecture in Japan in 2009 to examine the impact of in-vehicle traffic warning information (IVTWI) on traffic safety. To compare the impact of IVTWI provision on traffic safety, we examined three driving scenarios, (i) without IVTWI, (ii) voice-based IVTWI, and (iii) voice and image-based IVTWI. Driving risk was defined by three levels (low, medium, and high) based on the magnitude speed deviation using an ordered response probit model. Results show that traffic safety could be improved by IVTWI provision. A high driving risk, as derived from the proposed method, could explain the occurrence of up to 38% of traffic accidents. The results of the constructed model confirm that the probability of driving risk could be reduced by IVTWI provision.
In emerging countries such as India, traffic control and road-space allocation are generally biased toward vehicular traffic and the requirements of pedestrians are not given due consideration, making them desperate to cross roads even when conflicting vehicles are moving. This paper aims to investigate pedestrian-related safety aspects in urban India by estimating the post-encroachment time (PET) and the threshold wait time (TWT) for pedestrians during crossing. A representative traffic corridor in Kolkata city was taken as the case study and data were obtained from a questionnaire survey and videography at an intersection and a midblock section. A comparison of stated responses with the revealed behavior indicated that pedestrians generally overestimated the maximum waiting times. A low PET value was observed, which indicates the high risk of accidents for pedestrians under the prevailing conditions. The average TWT was 48 seconds, which indicates the need to reexamine signal design, enforcement practices, and the need for grade-separated crosswalk facilities. The results also indicate heterogeneity in TWT in terms of age and trip purpose of pedestrians.
The number of motorcyclist fatalities in Cambodia accounted for almost 70% in 2010 and 2011. The contributing factors to the severity of motorcycle casualties should be identified to provide worthwhile information for planning or policy making to reduce the severity of motorcyclist crashes. The aim of this research study is to analyze the factors affecting the severity of motorcycle casualties in Phnom Penh, the capital city of Cambodia, using a Bayesian approach to apply the ordered probit (OP) model, which is called the Bayesian OP (BOP) model. The advantage of the BOP approach is to allow the researchers to use prior information about the explanatory variables in fitting the models. Unlike OP, BOP produces reasonable estimated coefficients compared with OP when the sample size is small. This study found that male drivers, middle-aged groups (25 to 59 years), speeding, nighttime, peak hour, weekends, heavy truck crash opponent, crashing alone, and head-on collisions are more likely to result in higher levels of injury severity relative to its reference case.
In the event of traffic accidents on expressways, drivers may alter their travel choices differently based on their travel information styles, which have been under-researched. Using data collected from 1,923 drivers in Japan in 2011-2012, this study first defines the styles based on drivers' preferences for and experiences of travel information usage and then derives three unique styles: high dependence on information for relatively inflexible trip making (Style 1), high dependence on experience for risky trips (Style 2), and least-information users (Style 3). Furthermore, a nested logit-based driver adaptation choice model is estimated and the results indicate that drivers using Style 1 are more likely to change their original plan because of the information about substitute routes and travel modes than the other two types of drivers. The differences in influential information contents and their provision methods across the three types of drivers are shown in different driving scenarios.
Public transportation provides commuters with a convenient method to reach their destination faster and cheaper compared with private vehicles. However, this is not always the case for Metro Manila because many Filipinos have a negative perception of using public transportation. This paper first discusses the researchers' study of the travel behavior of Metro Manila commuters and the status of its public transportation sector based on their Metro Manila Public Transport Travel Survey. Information from the survey was used to implement a multimodal public transportation route planner for Metro Manila, which is designed to provide commuters with facts about public transportation. This should change its negative image and entice more people to use the services. The analysis of the publicly distributed General Transit Feed Specification data provided by the government is discussed. All these findings support the researchers' goal of improving Metro Manila's public transportation.
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