Annually, nearly 350,000 parked/disabled motor vehicle (PDMV) crashes occur in the U.S. in which an average of 507 occupants and non-motorists are killed and over thirty thousand people are injured. Among the safety measures aimed at reducing the frequency and severity of PDMV crashes, the deployment of flares is widely recommended and publicly accepted. The research documented in the present paper supplements the research literature on highway safety flare by addressing the relative effectiveness of the number of flares, flare placement and spacing, and the use of flares with and without the additional activation of a police vehicle's light bar. The behavior of nearly 4,000 passing vehicles was unobtrusively observed through the use of roadway sensors. The sensors counted the number and type of vehicles passing the study area (four lane interstate) and measured passing vehicle speed, lane distribution, and lateral separation from the roadway edge. Flares were found to have a significant and positive impact on all the dependent variables.
Abstract