The use of visual angle in car following traffic micro-simulation models

This paper presents a detailed literature review on car following models and methods used in describing the behaviour between two drivers of successive vehicles travelling in a traffic stream. The paper then concentrates on presenting a proposed car following model based on visual information which are perceived by the driver of the following vehicle. The model represents a modified version of similar models used in the past for describing the “leader-follower” behaviour which depends on the use of visual angle in determining the required spacing between pairs of vehicles. A sensitivity analysis is carried out in order to find out reasonable horizontal angular velocity threshold values which give best representation of driver’s reaction time. The capability of the model is then tested to represent the effect of size of vehicles on such threshold values and the required distance between vehicles. Further tests to calibrate and validate the proposed model are needed in order to represent real traffic behaviour using data from selected sites. The proposed model will mainly be used at a later stage in representing traffic behaviour at motorway ramp metering and measuring its effectiveness