Investigation of the Road Traffic Impacts of Green Light Optimal Speed Advisory Systems

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Although signalised intersections are necessary for urban road traffic management, they are also bottlenecks that disrupt traffic flow. Interrupted traffic flow at signalised junctions results in delays, stop-and-go conditions (i.e. acceleration/deceleration) and unnecessary waiting. Technological improvements pave the way for connected vehicles (CVs) to improve traffic flow and efficiency via advanced vehicular communication systems. An emerging application of infrastructure-to-vehicle (I2V) communication, called the Green Light Optimal Speed Advisory (GLOSA) system, recommends an optimal speed to individual vehicles that are approaching a traffic signal. This optimal speed advisory allows vehicles to pass through the traffic signal smoothly. This doctoral research aims to investigate the traffic impacts of the GLOSA system. The quantification is achieved through traffic simulation modelling. A control algorithm is developed for building the communication between the traffic signals and vehicles and replicating the GLOSA reflective decisions of vehicles. The algorithm enables vehicles to pass a traffic signal either without stopping or with minimal waiting times depending on the signal phasing and timing information. Therefore, unnecessary stopping, delays and waits at signalised junctions can be minimised. The proposed algorithm will be assessed with real-world traffic and signal data on a real-world road network in a simulation platform virtually. The analysis will be conducted under mixed traffic conditions involving both conventional and connected vehicles at different penetration and compliance rates. This will help to understand the performance of the GLOSA application under different conditions and identify how the future implementation of GLOSA may improve road traffic flows. Furthermore, the vehicles' trajectories data obtained from the simulation can be further used to estimate the impacts of GLOSA systems on vehicular emissions.