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 effect on casualties of a compulsory seat belt wearing law in South Australia

A compulsory seat belt wearing law in South Australia was preceded by a rise in the belt wearing rate and was accompanied by a further substantial rise. Casualty rates per 1000 involved vehicles, reported on a property-damage criterion, showed lower rates for 1967 and later models, which had belts compulsorily fitted, both before and after the wearing law. A before and after comparison showed reductions in the serious grades of casualties and an increase in the least serious. There was a differential effect on casualty reduction in 1967 and later models, which accounted entirely for the 7.5% overall reduction in the fatality rate. These comparisons are substantially free of effects due to concurrent changes in exposure to risk of accident and the observed reductions can be attributed to the belt wearing law.     

Effects of a mandatory safety belt law on hospital admissions

Although the effectiveness of automobile safety belts in reducing risk of serious injury in traffic crashes is well documented, safety belt use in many U.S. jurisdictions remains low. Michigan's mandatory safety belt law for front-seat occupants, implemented in July 1985, is one of 34 similar laws in the United States intended to increase belt use and reduce crash-related injuries. Using time-series intervention analyses of data from 14 hospitals throughout the state, we found a 19% reduction in the rate of admitted patients for all automobile occupant injuries and a 20% reduction in the rate of admitted patients with extremity injuries following implementation of the safety belt law. The utility of hospital data for the evaluation of interventions like the safety belt law reinforce the importance of consistently recording E-codes for all injury patients.     

Influence of safety belt usage on perception of the risk of an accident

Does the use of a safety belt increase or decrease the perception of the risk of an accident? Young and older male drivers were asked to drive an urban route and rate their perceptions of the risk of an accident. On the first driving trip all subjects were unbelted, while on the second driving trip half of the subjects wore a safety belt while half did not. Results indicated that young male drivers decrease their perception of the risk of an accident as they become familiar with a driving route if they are NOT wearing a safety belt. Young male drivers asked to wear a safety belt sustained their perception of the risk of an accident as they became familiar with the test route. Older drivers' perception of the risk of an accident was not affected by familiarity or safety belt usage.     

The effect of population safety belt usage rates on motor vehicle-related fatalities.

The effectiveness of safety belt usage in reducing mortality and morbidity among traffic crash victims has been well established. Population safety belt usage rates have been increasing from 11% in 1980 to 68% in 1995, as measured by observational surveys sponsored by the National Highway Traffic Safety Administration (NHTSA). Safety incentive grants from NHTSA to the States with higher than average usage rates are expected to total $500 million during 1999-2003. In this paper, longitudinal annual motor vehicle-related fatality levels are analyzed by state to estimate the effect of the population safety belt usage rate on traffic fatality rates in the presence of known confounders such as alcohol use and youthful drivers. Consideration of alternative models applied to 14 years of data shows that the population safety belt usage rate (at least, at the current rates) is associated with little or no effect on reducing fatality rates. On the other hand, higher safety belt usage rates arising from states with primary enforcement laws tend to suggest reductions in fatality rates. Such results call into question the NHTSA policy of basing incentive programs on overall safety belt usage rates.     

Traffic safety and the switch to a primary seat belt law: the California experience

This study explores whether the change of an existing seat belt law from secondary to primary enforcement enhances traffic safety. In particular, we examine traffic fatalities and injuries in California from 1988 to 1997. During the first half of this period, California law provided for secondary enforcement of its mandatory seat belt law, but in 1993 it upgraded the law to primary enforcement. Controlling for the number of motor vehicle collisions, a Box–Tiao intervention analysis of the time series is used to compare the monthly fatalities and injuries before and after the change in the enforcement provision. The results show that California experienced an improvement in traffic safety in terms of a significant reduction in injuries, but the change in enforcement provision had no statistically significant impact on fatalities.     

Investigation of factors significantly affecting child seat belt usage

The State of Victoria has enforced seat belt legislation for the past decade and at the same time carried out a large scale public education campaign. One significant group, children under 14 yr of age, within the population has not changed its seat belt usage behaviour. The paper discusses why the non-usage occurs and concludes that public education campaigns alone do not significantly affect behaviour. The two year project is the only reported seatbelt research where both the user's observed behavior and attitudinal statements were collected and matched.     

The influence of safety belt laws on self- reported safety belt use in the United States

We assessed rates and trends in safety belt use by presence and type of safety belt law using data from states participating in the 1984–1989 Behavioral Risk Factor Surveillance System. State(s) with a safety belt law allowing law enforcement officers to stop vehicles for occupants' failure to use safety belts (primary enforcement law) had greater and more rapid increases in safety belt use rates than did states with laws requiring that vehicles must first be stopped for some other violation before a citation or fine for occupants' failure to use safety belts could be imposed (secondary enforcement law). Larger and sustained increases in safety belt use occurred when safety belt laws became effective or when fines were imposed for violations than when laws were first enacted. These data suggest that primary enforcement laws result in greater and more rapid increases in safety belt use than do secondary enforcement laws, and that initial increases in safety belt use following implementation of laws are sustained.     

Seat belt use and accident involvement: A comparison of driving behavior before and after a seat belt law

In an earlier study, researchers at the University of North Carolina Highway Safety Research Center found drivers classified as seat belt nonusers on the basis of direct observation and self-reported belt use to be overrepresented in prior accidents and violations. This study represents a follow-up and extension of the earlier study where accident and violation rates over a 2.5-year interval following the classification by seat belt use status are compared. Seat belt nonusers were again found to be overrepresented in both accidents and violations. In other analyses of these data, changes in seat belt use status were found not to be associated with changes in accident or violation rates, and seat belt use rates reported by police in accidents following the mandatory seat belt law greatly exceeded both the observed and self-reported use rates. This was especially pronounced for drivers who responded that they rarely or never used seat belts.     

Demographic and socioeconomic correlates of safety belt use

This study analyzed the relationship between safety belt use rates—as measured by observational surveys at preselected sites—and demographic and socioeconomie characteristics—as reflected by the U.S. Census Bureau data for the sites. The results showed consistent and moderately high associations between observed safety belt use rates and socioeconomic status indicators, primarily home value. Once redundancies among variables were removed, other variables that contributed significantly to explaining differences between high- and low-belt use sites were the percentage of elderly people (55 + years old) and the mix of blue and white collar workers. Sites having high safety belt use rates had higher average home values, a higher percentage of elderly people, and a lower percentage of blue collar workers than sites having low use rates. Simple correlations with belt use rates were also obtained for race, marital status, presence of children in household, education, and income.     

A time comparison study of the New York state safety belt use law utilizing hospital admission and police accident report information

New York state enacted the first safety belt use law in the United States in 1984. We evaluated the effects of the law by reviewing all hospital admissions from motor vehicle crashes in Monroe County, New York. We compared admissions for the 18 months prior to the effective date of the law with those for the 18 months after the law became effective. Police accident reports and hospital records were coupled and intensively reviewed. Motorcyclists, pedestrians, and bicyclists (bicycle collisions with motor vehicles) became controls for the study. Seat belt usage was determined from police and hospital record information. Analysis of the data revealed that safety belt use among patients hospitalized because of motor vehicle accidents increased from 11.2% before the law became effective to 53% after the law became effective. Hospital admissions decreased 11.9% among motor vehicle occupants and increased 2.6% among controls. The ISS decreased from 16.01 to 14.55 for motor vehicle occupants and increased' from 14.77 to 15.11 among controls. Among subjects all injuries decreased except injuries of the spine and abdomen, which increased in the postlaw period.     

The effects of standard enforcement on Michigan safety belt use

The purpose of this study was to assess the effects of standard enforcement legislation on safety belt use in Michigan through a series of seven statewide direct observation surveys. A secondary purpose of the study was to compare the results in Michigan to the results in other states that have changed the provision of their mandatory safety belt use law from secondary to standard enforcement. The study found that standard enforcement has been effective in increasing safety belt use in Michigan. Immediately following the implementation of standard enforcement, Michigan's belt use rate increased to 83.5%, 13.4 percentage points higher than the highest rate previously observed. One year after the change, safety belt use in Michigan was still nearly 10 percentage points greater than the highest observed rate before standard enforcement legislation was enacted. Results indicated that safety belt use decreased slightly in the year following the implementation of standard enforcement. This appears to be an overall trend across all observed groups, and not due to any single demographic category. The results also suggest that standard enforcement legislation appears to have a greater effect on groups with historically low belt use, such as young people, males, passengers, and Black/African–Americans. When compared with other states that have made the change from secondary to standard enforcement, the increase in the safety belt use rate in Michigan was comparable to the increase seen in states with relatively high safety belt use prior to standard enforcement. However, states that had low safety belt use rates prior to adopting standard enforcement legislation observed a larger percentage point increase in the year following their change to standard enforcement.     

An evaluation of three corporate strategies for safety belt use promotion

Different types of awareness sessions to promote employee safety belt use were evaluated. Across eight different employee safety meetings three dichotomous variables were manipulated: the type of presentation format (lecture vs discussion), the presence or absence of safety belt pledge cards, and the presence or absence of an incentive component. All groups showed a four-fold increase in safety belt use. Five months after the interventions, belt use was still significantly higher than baseline levels. Generalization across employees was demonstrated by a significant increase in safety belt use for those who did not attend the awareness session. The awareness session with a discussion format influenced greater increases in safety belt use than did the lecture-based sessions, but pledge cards and incentives did not increase the impact of these awareness sessions.     

Increasing safety belt use in a secondary enforcement state: evaluation of a three-county special enforcement program.

Special enforcement programs to increase belt use present a unique challenge in states with secondary enforcement laws. This paper reports findings from an evaluation of a combined public information and education/enforcement program to increase restraint use along a highly traveled corridor in three Michigan counties. This program (US-31 SAVE) was successful in increasing belt use at least temporarily along the special enforcement corridor. Observed belt use increased from a baseline rate of 56.7% to 65.1% during the program before slipping slightly to 62.7% after the intensive enforcement and PI&E declined (all differences significant at p less than .05). This paper details program and evaluation activities and suggests future research needs to better understand the most effective mix of public information and enforcement efforts in states with secondary belt use laws.     

A comparison of safety belt use between commercial and noncommercial light-vehicle occupants

The purpose of this study was to conduct an observational survey of safety belt use to determine the use rate of commercial versus noncommercial light-vehicle occupants. Observations were conducted on front-outboard vehicle occupants in eligible commercial and noncommercial vehicles in Michigan (i.e.. passenger cars, vans/minivans, sport-utility vehicles, and pickup trucks). Commercial vehicles that did not fit into one of the four vehicle type categories, such as tractor-trailers, buses, or heavy trucks, were not included in the survey. The study found that the restraint use rate for commercial light-vehicle occupants was 55.8% statewide. The statewide safety belt use rate for commercial light-vehicles was significantly lower than the rate of 71.2% for noncommercial light-vehicles. The safety belt use rate for commercial vehicles was also significantly different as a function of region, vehicle type, seating position, age group, and road type. The results provide important preliminary data about safety belt use in commercial versus noncommercial light-vehicles and indicate that further effort is needed to promote safety belt use in the commercial light-vehicle occupant population. The study also suggests that additional research is required in order to develop effective programs that address low safety belt use in the commercial light-vehicle occupant population.     

Effects of incentive programs to stimulate safety belt use: A meta-analysis

The effects of campaigns using tangible incentives (rewards) to promote safety belt usage have been evaluated by means of a meta-analytic approach. Two coders extracted a total number of 136 short-term and 114 long-term effect sizes and coded many other variables from 34 journal articles and research reports. The results show a mean short-term increase in use rates of 20.6 percentage points; the mean long-term effect was 13.7 percentage points. Large scale studies report smaller effect sizes than small scale studies; when studies were weighted by the (estimated) number of observations, the weighted mean effect sizes were 12.0 and 9.6 percentage points for the short and long term, respectively. The main factors that influence the magnitude of the reported short-term effect of the programs were the initial baseline rate (which was highly correlated with the presence or absence of a safety belt usage law), the type of population involved, whether incentives were delivered immediately or delayed, and whether incentives were based on group or individual behaviour. Together these four variables accounted for 64% of the variance. Other variables, such as the duration of the intervention, the probability of receiving a reward, and the value of the reward were not related to the short-term effect sizes. The relationship between moderating variables and long-term effects was less clear.     

Willingness to use safety belt and levels of injury in car accidents

In this article, we develop a bivariate ordered Probit model to analyze the decision to fasten the safety belt in a car and the resulting severity of accidents if it happens. The approach takes into account the fact that the decision to fasten the safety belt has a direct causal effect on the category of injury if an accident happens. Our application to a sample drawn from the database of French accident reports in 2003 for three populations of car users (drivers, front passengers, rear passengers) shows that fastening the safety belt is significantly related to a decrease in severe injuries but it shows also that these car users compensate partly for this safety benefit. Furthermore, it is observed that demographic characteristics of car users, as well as transport facilities, play important roles in decisions to fasten safety belts and in the eventual resulting accident injuries.