Modification of Webster’s Delay Model for Heterogenous Traffic Conditions

Modification of Webster’s Delay Model for Heterogenous Traffic Conditions

Phenomenological Aspects of Civil Engineering (PACE) - an International Congress
Volume 1 - Issue 1 - PACE-2021

Sai Naveen Balla Bhavani Shankar Balla


Delay is an important traffic parameter in the evaluation of the signalized intersections. Estimation of delay is a very difficult task, as the delay is influenced by many variables. Webster and many others developed models to estimate the delay per vehicle at a signalized intersection under homogenous traffic conditions. The direct use of Webster’s model for the heterogeneous traffic conditions of developing countries like India will give underestimated delay values. So there arises a need to develop a model for delay estimation to suit the Indian traffic conditions. An attempt was made to develop a delay model by keeping the first and second terms as it is and modifying the semi-empirical term (third term) in Webster’s delay model. The data at different signalized intersections of Hyderabad city, India were collected by using a video camera. For extraction of the various traffic parameters, cycle by cycle analysis was done. The field delay was estimated using a distance-time plot drawn for the extracted GPS data of the probe vehicle. A multiple linear regression model was developed for modifying the semi-empirical term.


Delay; Webster’s delay model; cycle by cycle analysis; multiple linear regression; semi-empirical term