Preferred Following Distance and Performance in an Emergency Event while using Cooperative Adaptive Cruise Control

This study explored human factors issues associated with cooperative adaptive cruise control (CACC); specifically the relationship between drivers’ preferred following distance, assigned following distance, and driving performance. Participants drove in a dedicated lane and experienced a vehicle merging in front of their vehicle and later, an emergency event that required intervention in order to avoid a collision. Drivers followed at either a near or a far distance. Drivers’ perceived workload did not vary between the cruise and postmerge periods. However, workload was significantly greater after the emergency crash event. Workload did not vary significantly based on following distance assignment or preference. Those participants assigned to the near following distance were more likely to hover their foot over the brake during the merging event and to react faster to the emergency event. As with workload, performance (collision avoidance) did not vary significantly due to following distance assignment or preference. In other words, one’s abilities may not necessarily reflect their following preferences. This is a promising finding for widespread implementation of CACC.