Toll plazas in India are being operated electronically based on Radio frequency Identification technology (RFID) (FASTag). In RFID technology, the arriving vehicles should be stopped at the toll booth to confirm payment. In this procedure, a car slows down first, lines up, and then stops to be paid. Later, the car picks up speed gradually as it accelerates. Every such approaching vehicle is delayed by this process. The current study therefore, aims to determine the system latency in this procedure. The sum of waiting time and service time delays in mixed traffic situations is known as system delay. The queue's waiting time is the interval between when the first car enters the line and when it arrives at the booth for the transaction. The system delay model has been proposed with (a) queue waiting time and (b) service time. The field data is collected at selected toll plazas by video recording method. Field delay information has been used to validate the system delays as determined by models. It is found that the observed and estimated delay values do not significantly differ from one another. In order to estimate future vehicle delays, determine the Level of Service and determine the necessary number of toll booths, delay models have been proposed. These service delay models that were put out in the current study can be utilized to assess how well toll plazas work.