Effect of Heterogeneity of Traffic on Delay at Signalized Intersections

The average delay caused to vehicles at signalized intersections is an important criterion in the evaluation of performance at these intersections. Various models have been developed to estimate delay to traffic at signalized intersections. All the models are based on homogeneous traffic conditions; these models may not estimate the delays satisfactorily under heterogeneous traffic conditions. A probabilistic approach based on first-order second-moment method has been adopted to estimate the saturation flow and the delay caused to traffic, at signalized intersections, under heterogeneous traffic conditions. Here, the interaction between the different types of vehicles are incorporated in the modified 1958 Webster model by considering the intercorrelation between different vehicle groups. The input data required for these models and the data required to validate the calculated values were collected by conducting extensive traffic surveys. Results showed that the delay estimated using the probabilistic approach was close to the observed values of delay.