Traffic operations at mainline toll plazas

Most projects across the world are built under the public–private partnership (PPP) module. In the highway sector, the highway projects are built by the con-cessioner, and in lieu of that, he generates revenue by collecting tolls from road users. The toll plazas built across the highways to collect tolls act as a bottleneck in highway facilities. Although the toll collection system has been improved worldwide, users are still expe-riencing an enormous delay at toll plazas due to congestion, especially in developing countries like India. This congestion is caused due to various factors such as long service time, an inadequate number of windows, traffic volume, categories of toll rates, etc., which lead to delay, degradation of capacity, and level of service. Different researchers in their countries have analysed all these factors. The present article gives a detailed literature review summarizing various studies on the different parameters related to toll plazas and proposes research gaps from the perspective of developing countries. The challenges and methodology for evaluating various parameters are also discussed, and a way for-ward for future research is suggested.