Pilot Test of a Methodology for an Observation Survey of Motorcycle Personal Protective Equipment
Motorcycle personal protective equipment (PPE), an important traffic safety countermeasure, can include a safety-certified helmet, impact- and skid-resistant jackets and pants, motorcycle gloves, and sturdy, over-ankle boots. NHTSA, State highway safety offices (SHSO), and motorcycle safety groups conduct programs to encourage motorcyclists to use protective gear, especially helmets, but the impact of these programs is not well understood. Compared to observation surveys of seat belt use, observation surveys of motorcycle PPE use are not common, and the methodology for such surveys is not well established.
This study sought to develop a methodology for an observation survey of motorcycle PPE that would be resource-efficient, valid, and adaptable to any jurisdiction. The design was implemented in Florida, with two rounds of data collection. The survey used a probability-based sample of road segments stratified by four State regions and road types, including roads classified as motorcycle “Best Rides.” The sample selected road segments per probability proportional to size (PPS), with the length of road segment as the measure of size. The first round resulted in 841 motorcyclists observed, with a 43% mean use rate of USDOT-certified helmets, and a standard error of 17%. The second round of data collection adjusted the sampling by using an equal probability sample of road segments, not PPS. The second-round results resulted in 873 motorcyclists observed, with a 61% mean use rate of USDOT-certified helmets, and a reduced standard error of 7.7%.
The results suggest that it is crucial to oversample road segments that are likely to have higher rates of motorcycle traffic, such as the “Best Rides” stratum. In addition, oversampling arterial road segments may increase sample yields. Results also showed that selecting road segments per probability proportional to size (PPS) – when the measure of size is road segment length – was not efficient for motorcycle observations. A more efficient measure of size for motorcycle traffic is likely to be motorcycle volume at the road segment level. Otherwise, selecting road segments per equal probability, as opposed to PPS, may increase sample yield.
Read the full report here.