Examining the interaction between timing and modality in forward collision warnings

Rear-end collisions account for a high percentage of crashes and are largely attributable to driver inattention. Advanced crash warning systems offer the potential to mitigate such crashes by alerting the driver, reorienting attention, and speeding response time. Developing an understanding whether warning timing influences the effectiveness of different interface modalities is important, both for test protocol development and to understanding system limitations. To that end, the goal of this study was to examine the interaction between two warning timings (early and late) and six interface modalities in a forward collision event. Overall, earlier alerts led to faster and safer responses and several warning modalities were effective at orienting drivers' attention. Critically, interface modality did not interact with warning timing for any performance measure, indicating that the effects of different warning interfaces were consistent across warning timing. These results suggest that it may be appropriate to use the warning timing associated with the driver-vehicle interface during protocol testing for forward collision warnings.