Freeway speedharmonisation experiment using connected and automated vehicles

One effective strategy of cooperative vehicle‐highway systems with connected and automated vehicles (CAVs) is speed harmonisation, which dynamically adjusts vehicle speed recommendations to reduce speed differentials. Speed harmonisation can be applied to potentially improve mobility and safety. This study documents the development of an innovative vehicle control platform and experimental design to conduct speed harmonisation field experiments. In our experiment, a fleet consisting of three CAVs and five probe vehicles was deployed on a roadway segment that experiences daily recurring traffic congestion. The objective of the CAVs was to regulate traffic upstream of the bottleneck, so that vehicles move with uniform speed, thereby creating a steadier flow of traffic. The performance measures (e.g. travel time, fuel consumption, and speed oscillations) of the probe vehicles were analysed. To evaluate the effectiveness of speed harmonisation on smoothing the flow of traffic, these measures were compared between the probe vehicles that followed the CAVs. The results show the potential that CAVs have in reducing the oscillatory behaviour of traffic.