Effects of Cooperative Adaptive Cruise Control on Traffic Flow: Testing Drivers' Choices of Following Distances

A Cooperative Adaptive Cruise Control (CACC) system has been developed by adding a wireless vehicle-vehicle communication system and new control logic to an existing commercially available adaptive cruise control (ACC) system. The CACC is intended to enhance the vehicle-following capabilities of ACC so that drivers will be comfortable using it at shorter vehicle-following gaps than ACC. If this is shown to be the case, it offers a significant opportunity to increase traffic flow density and efficiency without compromising safety or expanding roadway infrastructure.This report describes the design and implementation of the CACC system on two Infiniti FX-45 test vehicles, as well as the data acquisition system that has been installed to measure how drivers use the system, so that the impacts of such a system on highway traffic flow capacity and stability can be estimated. The results of quantitative performance testing of the CACC on a test track are presented, followed by the experimental protocol to be followed for on-road testing with human subjects. Finally, the results from the first pilot test are presented to show how the data are analyzed to reveal the implications of CACC for driving behavior and user acceptance.