Traffic Flow Modelling for Congested Urban Road Links of Ahmedabad City

Knowledge of fundamental traffic flow characteristics and vehicle behaviour are necessary for appropriate operation of system. In developing countries like India, the urban road traffic, in particular, is highly heterogeneous. It comprises of vehicles of widely varying static and dynamic characteristics. Heterogeneous traffic flow creates enormous delay, wastage of fuel, air and noise pollution, accidents and interruption to emergency vehicles. The fundamental parameters of road traffic flow are speed, flow and density. If these parameters are measured properly on congested urban road links, then mathematical models can be developed. These models are basic need for quantifying capacity and consequently determining level of service of the road. Models for the free flow conditions are available for the congested Indian urban roads, but very few attempts have been made for developing model for the forced flow conditions. It is difficult to capture stop-and-go condition for developing the speed–flow relationship from the field observations. Hence, this study aimed to develop an appropriate methodology to collect the data for the stop-and-go condition particularly. The congested road links of Kalupur area of Ahmedabad city have been selected, where heterogeneous traffic is flowing creating enormous delay about more the one hour in the evening peak period. The data is collected by videography and then analysed for small time interval of 20–30 s. The speed–flow–density curves are plotted for free flow as well as for forced flow conditions, and different equations are obtained.