Two thirds of bicycle deaths occur as a result of traumatic brain injury; 88% of these injuries can be prevented by a helmet. In 1994, the State of California passed a law requiring all bicyclists under the age of 18 to wear helmets. Despite these legal obligations, many bicyclists still do not wear helmets. The estimates of bicycle helmet use is disparate throughout the state, with some communities reporting up to 80% use and others, especially inner-city areas, reporting less than 10% use.
The California Office of Traffic Safety (OTS) provides grants for bicycle helmet education programs led by local community organizations. The Traffic Safety Center (TSC) at the University of California, Berkeley, contracted with OTS to develop a set of instructions specifically for these community organizations to measure the impact of their safety intervention program. The instructions presented in this guide are designed to be used by these local programs to 1) evaluate the impact of their activities on bicycle helmet use, 2) evaluate results to improve or modify the programs as needed, and 3) meet contractual evaluation requirements.
In order to meet the goals, this document contains a description of important components of roadside observational studies and suggestions for conducting these studies, as well as information on how to analyze and interpret the results of roadside observational studies. Also, the TSC will offer direct support and guidance to those programs utilizing these instructions. As the law only requires persons 18 years old or younger to wear helmets, this guide focuses solely on youth. However, the same principles of roadside observation and analysis apply to adult bicyclists. Also, this guide addresses only helmet use. It does not prescribe methods of evaluating misuse of bicycle helmets.