An Investigation of the Impact of Advanced Vehicle Technologies on Traffic Operations

This paper explores the impact of Advanced Driver Assistance Systems (ADAS) on traffic operations, capacity, and congestion. ADAS can take control over specific functions of the vehicle, and provide warnings to assist drivers in a variety of driving tasks. These technologies were designed mainly to improve safety and provide comfort to drivers. There is evidence that these systems may change the way drivers behave on the road, resulting in traffic operational improvements, but a limited amount of research has been conducted to assess these potential impacts. This study evaluated these impacts in two ways: a) through a driver simulator (STISIM Drive) study using a vehicle equipped with two types of ADAS: Adaptive Cruise Control (ACC) and Lane Change Assist (LCA); b) through a microsimulator study by replicating the movement of vehicles equipped with ACC and LCA. The two studies showed that there are potential changes in driver behavior, and subsequently in traffic operations, when ADAS are installed in the vehicle. Also, the impact of the systems is different for different driver types (aggressive vs. conservative). It was concluded that for the conditions tested the ACC can significantly increase speeds for congested conditions, even at the lowest market penetration scenario tested (20% ACC in the traffic stream). When only the LCA was present the number of lane change maneuvers increased, the throughput (VMT) increased, and travel time was not significantly affected. When both LCA and ACC were present, conditions improved significantly, and similarly to when ACC was available by itself.