Estimation of system delay based toll equivalency factors at toll plazas using simulation

The service time and time headway of the vehicles are used to define the equivalency factor of different vehicle classes at the toll plaza. Both the service time and time headway are point measures and do not account for the system delay (time difference when a vehicle enters the queue and leaves the tollbooth) caused to the vehicle. The present study aims to quantify the system delay incurred to the vehicles at electronic toll collection (ETC) lanes under mixed traffic conditions using a microsimulation approach. Field data collected from one toll plaza located on a National Highway are used for simulation model generation. A new terminology called system delay-based toll equivalency factor (DTEF) is introduced to convert the different vehicle classes into equivalent passenger cars. The DTEF variation for different approach volumes and heavy commercial vehicle (HCV) compositions were checked at different ETC penetration levels. A total of 288 scenarios have been worked out, and simulation runs have been made for all such scenarios to obtain the DTEF values. The average DTEF value of HCV was obtained as 2.20. Further, it is found that with an increase in approach volume and HCV share in the traffic stream, the DTEF value increases. The outcome of the present study will be useful to field practitioners and engineers to determine the capacity in equivalent DTEF/hr and level of service of a toll plaza in terms of system delay.