Injury Risk in Collisions Involving Buses in Alberta, Canada

With 2000 to 2007 crash data, this study investigated the factors that contributed to injuries in collisions that involved at least one bus in the province of Alberta, Canada. Crashes of all types of buses (e.g., school, transit, intercity) were considered. Four logistic regression models were calibrated: single-vehicle collisions on highways, single-vehicle collisions on nonhighway locations, two-vehicle collisions on highways, and two-vehicle collisions on nonhighway locations. The analysis showed that weather conditions were a significant contributing factor in all four types of collisions, although crashes in adverse weather conditions resulted in fewer injuries. The type or collision, characteristics of collision partner, driver age of collision partner, and weather conditions had a significant effect on the level of severity of collisions on both highway and nonhighway locations. Other factors were shown to affect injury risk only in one particular situation. For instance, for highway-related collisions, the age of the collision partner had a significant effect on levels of accident severity, whereas the age of the bus driver did not. In addition, for highway collisions, the severity was higher for head-on crashes, bus-bus crashes, bus-truck crashes, bus-motorcycle crashes, older buses, crashes on grade and in sags, and crashes during dark and sun glare, whereas accident probability decreased with larger outside shoulder width. For nonhighway locations, crashes occurring near tunnels, overpasses, and signalized intersections were shown to result in a higher probability of injury. The results showed that single-bus collisions involving pedestrians at non highway locations had higher injury risk than collisions involving objects.