B.J. Campbell

Evaluating the North Carolina safety belt wearing law

The North Carolina Seat Belt Law required an evaluation of the effectiveness of the act with a report of the findings to the Legislature three years after the law went into effect. This paper addresses changes in statewide belt usage and in occupant injury associated with that law. Observational data collected bimonthly from a probability sample of 72 sites stratified by geographic region, rural/urban location, road type, and time of day show that belt use rose from a baseline rate of 25% to a warning ticket phase rate of 45%. Belt use then reached 78% upon enforcement and is now nearly 64%. Time series analysis showed that statistically significant reductions in percentages of moderate and serious injuries occurred at the beginning of both the warning ticket and the enforcement phases. Forecasts of injuries and deaths were also developed from the time series models and were compared with observed totals. Warning tickets brought about a modest 5.4% reduction in serious injuries; fatalities among occupants covered by the law showed no change. In contrast, the subsequent enforcement phase saw a reduction of 11.6% in fatalities and 14.6% in serious or worse injuries. This represents an estimated annual savings of 131 lives and over 2,300 serious injuries in North Carolina during the 18 months following onset of enforcement.

THE ASSOCIATION BETWEEN ENFORCEMENT AND SEAT BELT USE

A statistical association is found between the number of traffic citations for belt law violations versus observed belt use. Also, belt use is higher in primary enforcement states where officers issue such citations for belt law violations alone. In secondary enforcement states officers issue such citations only after stopping motorists for another reason. Most belt laws provide for secondary enforcement. Enforcement data were confined to the highway patrol in each state (local arrest data are rarely compiled statewide). Belt use data were based on observational surveys conducted in each belt law state.

CHANGE IN INJURIES ASSOCIATED WITH SAFETY BELT LAWS

Statewide crash data bases from nine states were subjected to time series analyses to detect changes in injuries associated with onset of seat belt laws in the respective states. In each of 18 analyses involving drivers covered by the law observed casualties were below the number forecast on the basis of prior experience and assuming that no law had been enacted. In the case of others, not covered by the law, observed injuries were equally often above or below forecast. Relative to covered drivers not only were the numbers below forecast, but in 12 of the 18 instances there was a statistically significant indication of an abrupt decrease the month the law began.

Survey of attitudes of drivers in air bag deployment crashes

Abstract A systematic sample of 215 drivers who had been in police reported crashes in North Carolina in which their cars air bag deployed were surveyed regarding their experiences. The respondents were generally favorable toward air bags, and almost all indicated that they would want an air bag in their next car. The overwhelming majority thought their air bag protected them from injury, although many respondents reported minor crash and/or air bag related injuries. Many respondents (44%) did not recall anything particular about the air bag deployment event; about one in five remembered something they perceived as a problem. Dust, odor, noise, and “smoke” were the most frequently recalled events with dust and odor being perceived most often as problems.