Almost all such crashes involve only 1 vehicle. Roadside hazard crashes occur in both urban and rural areas but are mostly a problem on rural roads. More than a third involve a vehicle that rolls over, and about a third involve occupant ejection. Trees are by far the most common objects struck in roadside hazard crashes. Alcohol is a frequent contributing factor in these crashes.
Motorists also run off the road because of excessive speed, fatigue, or inattention.
Efforts to reduce these driver errors are only somewhat effective, so it's important to shield or remove stationary objects or avoid putting them along roads in the first place, especially roads where vehicles are more likely to leave the pavement. The proportion of motor vehicle deaths involving roadside hazards has remained between 28 and 30 percent since 1979. Forty-four percent of drivers killed in roadside hazard crashes in 1999 had blood alcohol concentrations at or above 0.10 percent. Drivers of 43 percent of the vehicles in fatal roadside hazard crashes in 1999 were men younger than 35. Forty-one percent of deaths in roadside hazard crashes in 1999 involved vehicles rolling over.