Testing alternative designs for a roadside animal detection system using a driving simulator

Objectives: A Roadside Animal Detection System (RADS) was installed in January 2012 along Highway 41 through Big Cypress National Preserve in Florida, USA in an attempt to reduce wildlife-vehicle collisions. The system uses flashing warning signs to alert drivers when a large animal is near the road. However, we suspected that the RADS warning signs could be ignored by drivers because they resemble other conventional signs. We hypothesized that word-based warning signs (current design) are less effective than picture-based signs at catching drivers’ attention. Methods: We used a driving simulator to test (1) the effects of the RADS on collision rate, driver speed, and latency to brake; and (2) whether the RADS would be more effective if warning signs were picture-based. Participants were randomly assigned to one of three treatments: no warning (control), word-based RADS signs (current design), and picture-based RADS signs (proposed design). During the simulations, a deer entered the road in front of the driver, and we recorded whether drivers “crashed” or not. Results: Both the picture-based and word-based RADS signs resulted in significantly lower crash probabilities. The picture-based RADS signs performed better than the word-based signs in reducing speed and latency to brake, although the effect varied between twilight and night. However, the word-based RADS signs still did produce significant reductions in speed and braking latency. Conclusions: We conclude that the word-based RADS in Big Cypress should help prevent dangerous wildlife-vehicle collisions, but that redesigning the warning signs to be picture-based could yield even greater benefits.