AUTOMATED VEHICLES AT SIGNALIZED INTERSECTIONS – IMPACT OF COMMERCIAL ADAPTIVE CRUISE CONTROL (ACC)

The first generation of autonomous vehicles are equipped with Adaptive Cruise Control
(ACC), which automatically adjusts the vehicle speed to maintain a safe following distance and gap selected by the driver. Today’s ACC can also operate at low speeds and signalized intersections on arterial streets. However, the latency of the on-board sensors can significantly increase the start-up lost time and reduce capacity and increase delay on arterials with signalized intersections. This study investigates the fundamental characteristics of traffic flow under ACC vehicles and mixed driving scenarios. Field tests demonstrated that the design of ACC vehicles can lead to delayed response and gradual acceleration when operating on arterials with speed fluctuations due to disturbances. This study also examines the effect of increasing adoption of ACC vehicles at signalized intersections. Field validated simulations suggest that 100% market penetration of ACC vehicles could decrease the capacity by up to 10%. Furthermore, fuel consumption and emissions (CO2, NOx, CO, HC) can increase by up to 33%.