Technical evaluation of GLOSA systems and results from the field

The goal of Green Light Optimal Speed Advisory (GLOSA) systems is to lower CO2 emissions and to avoid unnecessary stopping in intersection approach scenarios by giving speed advices to drivers based on current and future traffic light signal phase timings. These systems have been widely evaluated by means of simulation and, while most research focuses on the impact assessment of GLOSA along with environmental influences, minor attention was drawn to the holistic technical evaluation of included sub-modules and implementations. In this paper we address this problem with a novel and holistic concept for the technical evaluation of IEEE 802.11p based GLOSA systems. We introduce metrics to cover the whole spectrum of GLOSA operations and identify important factors that are usually not considered in simulations, yet, strongly influencing the results. We demonstrate how this concept is used to evaluate the real-world GLOSA system tested in the European Commission co-funded field trial DRIVE C2X. Results derived from Field Operational Test (FOT) data show that our metrics are well-suited to assess the performance of the GLOSA system, but also to identify sources of potential problems or bottlenecks. Based on our findings, we argue that most simulation studies are too optimistic and that further considerations are required to deploy real-world GLOSA systems.