Transportation & Vehicle Safety Policy


Rear End Crash Avoidance System (RECAS) Algorithms and Alerting Strategies: Effects on Performance and Acceptance

This study examined driver response to different values of the deceleration warning parameter to quantify the effects of this parameter on driver response and algorithm effectiveness.

Our task in this study was to code foot behavior for decomposing reaction time. Three specific measures were gathered from the data: reaction time, accelerator-to-brake transition time, and brake-to-maximum brake transition time. Accelerator release reaction time measures the reaction time to the braking event or the reaction time to the warning. Reaction time to the braking event was calculated for each driver, whereas reaction time to the warning was calculated only for those drivers assisted by the RECAS. Accelerator-to-brake transition time specifies the time between driver release of the accelerator and application of the brakes. Brake-to-maximum brake transition time measures the time required by the driver to reach maximum deceleration after the initial depression of the brake pedal.

Analysis of the braking process showed that while warnings have the ability to reduce the time it takes for the driver to release the accelerator, they do not speed application of the brake, increase maximum deceleration, or affect mean deceleration. These results are helpful for devising a computational model of driver performance and identifying the most promising parameter settings.