Real-world effects of rear cross-traffic alert on police-reported backing crashes

February 2019

Objective: Several parking assistance systems are available to help drivers back up. Rear cross-traffic alert warns drivers when they are reversing and cross-traffic approaches the rear of their vehicle, as might happen when backing out of a perpendicular parking space in a lot. The goal of this study was to examine the effect of rear cross-traffic alert on backing crashes. Methods: Negative binomial regression was used to compare police-reported backing crash rates in 25 U.S. states per insured vehicle year between General Motors and Mazda vehicles with rear cross-traffic alert and the same vehicle models without the optional system, controlling for the presence of other parking assistance systems and additional factors that may affect crash risk. Results: Crash involvement rates in backing crashes overall were 22% lower among vehicles with rear cross-traffic alert than among vehicles without the system when averaged between the two manufacturers. Rates were 32% lower among vehicles with the system than without in two-vehicle backing crashes where the vehicles were traveling in perpendicular directions. Both reductions were statistically significant. Conclusions: Rearview cameras and rear automatic braking, which are designed to help drivers detect and brake for obstacles directly behind the vehicle, have been shown in previous research to be effective in reducing backing crashes reported to the police. Rear cross-traffic alert can complement these systems by preventing potential backing crashes that other parking assistance systems are not designed to detect. Manufacturers should equip vehicles with rear cross-traffic alert, in addition to other parking assistance systems like rear automatic braking, to maximize the number of backing crashes prevented.