Sudip Barua

Investigation of time and weather effects on crash types using full Bayesian multivariate Poisson lognormal models

Previous research shows that various weather elements have significant effects on crash occurrence and risk; however, little is known about how these elements affect different crash types. Consequently, this study investigates the impact of weather elements and sudden extreme snow or rain weather changes on crash type. Multivariate models were used for seven crash types using five years of daily weather and crash data collected for the entire City of Edmonton. In addition, the yearly trend and random variation of parameters across the years were analyzed by using four different modeling formulations. The proposed models were estimated in a full Bayesian context via Markov Chain Monte Carlo simulation. The multivariate Poisson lognormal model with yearly varying coefficients provided the best fit for the data according to Deviance Information Criteria. Overall, results showed that temperature and snowfall were statistically significant with intuitive signs (crashes decrease with increasing temperature; crashes increase as snowfall intensity increases) for all crash types, while rainfall was mostly insignificant. Previous snow showed mixed results, being statistically significant and positively related to certain crash types, while negatively related or insignificant in other cases. Maximum wind gust speed was found mostly insignificant with a few exceptions that were positively related to crash type. Major snow or rain events following a dry weather condition were highly significant and positively related to three crash types: Follow-Too-Close, Stop-Sign-Violation, and Ran-Off-Road crashes. The day-of-the-week dummy variables were statistically significant, indicating a possible weekly variation in exposure. Transportation authorities might use the above results to improve road safety by providing drivers with information regarding the risk of certain crash types for a particular weather condition.

Factors Influencing the Safety of Urban Residential Collector Roads

ABSTRACT This study investigated the impact of various road elements on collision frequencies for urban residential collector roads. Negative binomial safety performance functions were developed for total collision occurrence and severity using 4 years of data from the City of Edmonton. The proposed models were estimated using the maximum likelihood estimation technique. Scaled deviance and the Pearson chi-squared statistic were used to assess the models’ goodness of fit. Results revealed that the property-damage-only (PDO) collision model has the same significant covariates as the total collisions model. For predicted total and PDO collisions, there is a statistically significant positive relationship between collisions and access-point density, stop-controlled intersection density, the presence of a horizontal curve, licensed premises, seniors’ centers, and on-street parking. For severe (i.e., fatal and injury) collisions, the results were quite similar to the total and PDO collisions with some exceptions (e.g., number of lanes, bus-stop density). On the contrary, there is a significant negative relationship between predicted severe collisions and the presence of a median, center line, and manned enforcement. The city authority could use this information to assess the associated safety risk of residential collector roads and, hence, prioritize collision prone road segments.

Assessment of the Role of Training and Licensing Systems in Changing the Young Driver's Behavior

ABSTRACT Young driver crashes are over represented in any countrys crash statistics. This problem is more acute in developing countries where the law enforcement is not strict and the licensing structure is not well developed. According to World Health Organization (WHO) road crashes are the single greatest cause of death for men aged 15-29 years old. More than 8500 young drivers die each year in the Organization for Economic Co-operation and Development (OECD) countries and the death rates for young drivers are doubled than the older aged drivers. Young driver crashes and deaths cause great economic, social cost on individuals, families and societies. Many research studies have been conducted to find out the causes of crash and deaths. These found that the conventional youth training schemes help young learner to develop their driving skills and knowledge, meanwhile they do not help to gain real road driving experience. Research shows that the lack of driving experience, higher order perception and maturity increase young driver crash exposure. To this end, Graduated Driver Licensing System (GDLS) have been developed. GDLS helps young drivers to focus on road driving experience and it divided the whole licensing process into different phases. It also helps the young drivers to get supervised driving experience which help them to accumulate driving hours to get the provisional license. The GDLS helps not only in gaining experience in driving but also in developing the higher order perception (hazard perception) which is very much needed during driving. This paper discusses a number of drivers licensing systems and training programs and highlights the need for a licensing system that focus not only on the development of better hazard perception and understanding the road environment for young drivers but also on some other factors that affect road safety. It is argued that the consultation of community concerning the development of a licensing system is essential to minimize road crashes in the youth group as it would guarantee that the young drivers are fully aware of various driving risk factors at training stage rather than the practicing stage.

Conceptual Physical Design of Bus Rapid Transit (BRT) in Dhaka

Dhaka, the capital city of Bangladesh, is the largest and most industrialized city with 15 million people. Due to rapid unplanned development, versatile land use, rapid population growth, poor public transport system, and increase of private car users, traffic problems are worsening day by day. The only mass transit is bus, which is insufficient in terms of safety, capacity, comfort, and convenience. Considering the worsening congestion it is high time to develop an effective mass transit system such as Bus Rapid Transit (BRT) as a means for achieving sustainable urban transport in the city. In this paper an attempt has been made to propose a conceptual physical structure of BRT for the line3, which starts from Uttara and ends in Ramna covering around 18.5 km. The BRT stations and runways are designed in a way to satisfy the ever-increasing public transport demand of achieving a sustainable urban public transport system.

Opportunities and Operational Difficulties of Introducing Bus Rapid Transit (BRT) in Dhaka

Dhaka is one of the most densely populated cities in the world. The abrupt increase in population along with diverse urban land use patterns has engendered an ample travel demand. In addition, gradual deterioration of level of service of the public transport system and increasing private car ownership create acute intolerable congestion. In these circumstances, Bus Rapid Transit (BRT) is one of the most effective short-term solutions because of its high capacity as well as relatively low construction and operating cost. Despite the high opportunities of introducing BRT in Dhaka, it will face some operational difficulties such as high occupancy, high operational fleet size, small headway, priority in intersection and signal control, etc. Results show that to satisfy the projected high passenger demand, the headway will be 16 seconds and operational fleet size and vehicle occupancy will be very high in many locations, which will make the BRT operation difficult and ineffective.

Modal Integration for Improving Urban Mobility in Dhaka

About 15 million people live in Dhaka, the capital city of Bangladesh, with a growth rate of 1.8%, which creates huge travel demand as well as numerous transport problems. Lack of effective public transport system and door-to-door service influence the augmentation of private cars, which is causing congestion and deterioration of the environment. Though railway is a very popular, safe, and cheap transport system of Bangladesh, in absence of proper initiatives and investments, the railway could not play the much expected role in Dhakas public transport system. However, Dhaka is surrounded by four rivers providing an inbuilt facility for operation of circular waterways, due to financial constraint and lack of appropriate planning for interconnectivity among other modes, its not serving effectively. The airport is in the northern part of Dhaka, which does not have any integration with the public transport system, railway stations, and waterway terminal. Through the development of the public transport system using Mass Rapid Transit, Bus Rapid Transit, and commuter rail service along with proper integration of airway and the circular waterway, an effective sustainable integrated transport system can be achieved in Dhaka. In this paper an attempt has been made to develop an effective integrated transport system by integrating and improving systematic, effective, and safe operation of all modes. Besides these, the present scenario of the transportation system of Dhaka city is illustrated in the context of transport demand and supply and also discusses potential initiatives that will lead to a sustainable integrated transportation system.