Trends in fatal motorcycle crashes: California, 1988-2006

Background/Purpose: To describe the recent increase in fatal motorcycle crashes and explore reasons for this increase.

Methods: We obtained crash data from the California Statewide Integrated Traffic Records System and California records from the Fatality Analysis Reporting System. Tabular and graphical methods were used to examine temporal trends and personal, vehicle, and collision characteristics.

Results/Outcomes: The annual number of motorcyclists involved in fatal crashes in California has increased each year from a low of 211 in 1998 and to 520 in 2006 (an increase of 146%). During the same period, the rate of fatal collisions per 1000 registrations increased 32% and the rate per 1000 motorcycle licenses increased 81%. In fatal crashes, the percentage of motorcyclists age 45 years, of motorcycles with engine displacement >= 1.2 liters, and of Harley-Davidson motorcycles all increased. Each of these trends generally conforms to changes in the national use of motorcycles. Crash severity has increased somewhat over the same period: fatal and severe crashes increased from 27% of all injury crashes in 1998 to 31% in 2006. Motorcyclists were at fault in 39% of multi-vehicle fatal collisions in 1998 and 42% in 2006. The proportion of motorcyclists in fatal crashes with blood alcohol >=0.01% decreased from 31% in 1998 to 23% in 2006.

Conclusions: Fatal motorcycle crashes, registrations and licensure increased dramatically from 1998 to 2006.

The increase in fatal motorcycle collisions in California appears to be due more to an increase in exposure than to changes in the risk of motorcyclist.