Wing-gun Wong

AN ALGORITHM FOR ASSESSING THE RISK OF TRAFFIC ACCIDENT

INTRODUCTION This study is aimed at developing an algorithm to estimate the number of traffic accidents and assess the risk of traffic accidents in a study area. METHOD The algorithm involves a combination of mapping technique (Geographical Information System (GIS) techniques) and statistical methods (cluster analysis and regression analysis). Geographical Information System is used to locate accidents on a digital map and realize their distribution. Cluster analysis is used to group the homogeneous data together. Regression analysis is performed to realize the relation between the number of accident events and the potential causal factors. Negative binomial regression model is found to be an appropriate mathematical form to mimic this relation. Accident risk of the area, derived from historical accident records and causal factors, is also determined in the algorithm. The risk is computed using the Empirical Bayes (EB) approach. A case study of Hong Kong is presented to illustrate the effectiveness of the proposed algorithm. RESULTS The results show that the algorithm improves accident risk estimation when comparing to the estimated risk based on only the historical accident records. The algorithm is found to be more efficient, especially in the case of fatality and pedestrian-related accident analysis. IMPACT ON INDUSTRY The output of the proposed algorithm can help authorities effectively identify areas with high accident risk. In addition, it can serve as a reference for town planners considering road safety.

Laboratory Performance Evaluation on Polymer Modified Porous Asphalt Concrete

This paper presents the details of the laboratory performance evaluation of the three types of polymer modified binders and their respective porous asphalt concrete. The same gradation was applied to all the mixtures and the base bitumen was Shell 60/70. The binder test results indicate that the SBR and SBS modified binders have the smaller temperature susceptibility and exhibit better performance in resisting ageing, rutting, and fatigue than the conventional penetration 60/70 binder. When evaluated in a series of laboratory tests designed to assess the fundamental mechanical properties and durability performance of porous asphalt concrete, the results show that the SBS modified porous asphalt concrete exhibits the most overall satisfactory performance with respect to stiffness, dynamic creep deformation, rutting, and moisture resistance damage among the three types of porous asphalt concretes studied. Based on the lab results and the cost-effectiveness analysis, the SBS modified porous asphalt concrete is recommended as the most favorable material to be used as a friction course in Hong Kong.

Optimizing Passenger Train Services: A Model and a Genetic Algorithm Solution

Planning for passenger train services plays a vitally important strategic role in railway transportation. The objective of such planning is to achieve maximum net revenue for the rail operator whilst maximizing some specified functions of overall community benefit. However, there usually exists a trade-off between attracting passenger traffic and reducing operating costs. This paper puts forward a non-linear integer-programming model to optimize that trade-off. A Genetic Algorithm (GA) is introduced to solve the optimization problem efficiently. The model is described in the paper, together with the solution method. The paper also gives an example application of the proposed model by designing a passenger train service plan for China’s GuangShen quasi-high-speed railway. The solution process is outlined in detail. A GA was found to be an effective technique to solve the stated transportation optimization problem. The procedure adopted here allows for practical considerations to be taken into account by providing a range of sub-optimal solutions in addition to the global optimal solution.