A photograph-based study of the incidence of fatal truck underride crashes in Indiana.

Photographs were used to estimate the incidence of fatal crashes in which passenger vehicles underrode the fronts, sides and rears of large trucks in Indiana during 1993. The photographs were obtained for 98 of the 107 eligible fatal crashes between large trucks and passenger vehicles in 1993. A protocol was developed to judge the presence and extent of underride, the presence of intrusion into the passenger vehicle compartment, and the likelihood of death or serious injury if underride had been prevented. The incidence of fatal underride was compared with the incidence reported in the Fatality Analysis Reporting System (FARS), a census of fatal crashes on public roads in the U.S.A. For the same 107 fatal large truck-passenger vehicle crashes, the incidence of underride reported in FARS was much lower than in the photograph-based study: 6 versus 63%. Photographs contain details absent from police reports, the primary data source for FARS, and thus enable more complete identification of underride crashes. Preventing underride would have substantially reduced the likelihood of death or serious injury in ca 20% of the underride crashes.