The purpose of this document is to report on several recent studies sponsored by the NHTSA to determine what happens to helmet wearing when mandatory helmet usage laws are repealed, and the effect that any reduction in use has on the number of head injuries among accident-involved motorcyclists. Riders who do not use safety helmets have twice as many moderate to serious head injuries, and three to nine times as many fatal head injuries as riders wearing helmets. Helmet Wearing rate is very high (90% to 99%) in States with usage laws, but falls rapidly to less than 60% following repeal. In States without usage laws, wearing rates for riders in fatal crashes is very low (10 to 39%) reflecting the greater risk of a fatal head injury to the unhelmeted rider. In the three States for which pre and post repeal crash data were available (Colorado, Kansas, and South Dakota) the frequency of head injuries to all crash involved riders (helmeted and unhelmeted) rose following repeal of the States' usage law. Fatal head injuries double. Claims that safety helmets cause accidents by interfering with vision or hearing or that they cause neck injuries, are not supported by data from a detailed accident investigation study. The data summarized in this report give strong evidence for the effectiveness of safety helmets and of helmet usage laws.
Samenvatting