Potentials and limitations of Green Light Optimal Speed Advisory systems

The reduction of CO
₂
emissions is one of the most anticipated features of future transportation systems. Smart traffic lights are believed to contribute to achieving this by either adapting their signal program or by informing approaching drivers. In this paper we investigate the potentials and limitations of the latter, that is, Green Light Optimal Speed Advisory (GLOSA) systems in a realistic, large scale simulation study. We examine the impact of different equipment rates of both traffic lights and vehicles on environmental related metrics but also study how these systems can increase the comfort for drivers by reducing waiting times and the number of stops. We find that at low traffic densities these systems can meet all their goals and lower CO
₂
emissions by up to 11.5% whereas in dense traffic several side-effects could be observed, including overall longer waiting times and even higher CO
₂
emissions for unequipped vehicles.