Traffic State Estimation near Signalized Intersections

The primary goal with which any transportation system is designed is to make efficient use of the available infrastructure to achieve better level of service (LoS). However, LoS is observed to be deteriorating on urban roads, especially near signalized intersections, primarily due to the suboptimal operation of traffic signals. To achieve optimal performance of traffic signals, knowledge about the traffic states prevalent in the vicinity of the intersection is essential. Traffic states in general can be estimated at both macroscopic and microscopic level by employing various mathematical and data-driven approaches. However, obtaining these variables near the intersection is difficult and challenging under varying traffic conditions. This paper presents a systematic review of the state of the art in traffic state estimation (TSE) near signalized intersections both under homogeneous, lane-based, and heterogeneous less lane disciplined (HLLD) traffic conditions. This is expected to be a guide to traffic engineers, decision makers, and researchers aiming to gain pertinent knowledge about the sensors that can be used, data that needs to be collected, estimation methods that are suitable, and the intersection performance measures that need to be evaluated. The gaps in the current state of the art and future research directions are highlighted. In addition, insights on ways to address challenges pertaining to TSE near intersections under HLLD traffic conditions are also discussed.