Alcohol Use and Motorcycle Accident Causation in Thailand and Los Angeles 2005-32-0003

Motorcycle accident cause factors in two studies - one in Los Angeles (1976-77) and one in Thailand (1999-2000) are compared. In both, teams of investigators conducted detailed on-scene investigation immediately after each crash, then reconstructed each and identified the cause factors. Rider alcohol use was significantly higher in Thailand than Los Angeles (37% vs. 12%). Alcohol-involved crashes were remarkably similar in both studies, with higher rates of rider error, inattention, red light violations, loss of control and single-vehicle crashes (usually with the motorcycle running off the road). In contrast, non-alcohol crashes were very different in the two study areas. In Los Angeles, car drivers were most often responsible for multi-vehicle crashes and usually said they hadn't seen the motorcycle. Thailand drivers rarely said they hadn't seen the motorcycle. This difference in motorcycle detection may be due to the high frequency of motorcycles in Thailand traffic (about 1 in 3) compared to Los Angeles (about 1 in 200). Other global factors such as congestion and expectations about other drivers' behavior appeared influence accident causation.