Piti ROTWANNASIN
Graduate student
Transportation Research Laboratory
Department of Civil Engineering,
Chulalongkorn University, 10330 Thailand

Kasem CHOOCHARUKUL, Ph.D.
Lecturer
Transportation Research Laboratory
Department of Civil Engineering
Chulalongkorn University, 10330 Thailand

ABSTRACT

This paper aims to examine fundamental issues related to the operational quality of urban multilane traffic. A methodology is developed to investigate to what extent the current capacity analysis procedures outlined in the HCM can be applicable and transferred to urban highways in Bangkok. A number of multilane highways located in Bangkok area are selected for the present study and traffic data are collected by video cameras so that traffic movement as well as congestion could be visually observed. Several microscopic traffic flow characteristics such as vehicular speed, flow, and density are decoded and extracted by image processing unit. Based on the collected traffic data, a set of models for determining highway capacity is proposed and underlying factors that affect highway operations are identified. The proposed models are evaluated and compared against HCM in terms of predicting accuracy of highway capacity. Preliminary results show that the models developed in this study can provide more accurate means in predicting highway capacity and quality of service pertaining to Bangkok highways, and the application of the models could sufficiently serve the needs for transportation engineers. Despite an exploratory study, the findings in the present study provide a promising ground for developing a country-wide comprehensive capacity analysis manual similar to those used in the western region.