The effectiveness of the Canadian mandatory seat belt use laws

The impact of four provincial mandatory seat belt use laws passed in 1976 and 1977 on seat belt use and on motor vehicle occupant casualties is examined. Subsequent to the passage of the laws, belt use typically increased from 20 to the 70% level dropping to around 50% over the next several years. Ontario exhibited a clear drop in the fatality and injury rates in the years following the introduction of the law. Quebec experienced little reduction in casualties. The changes in casualties for British Columbia and Saskatchewan were mixed with the former showing a drop only in the fatality rate subsequent to the seat belt law, while the latter experienced a reduction only in the injury rate. The provinces without seat belt use laws also enjoyed some reductions in occupant casualty rates. The changes in occupant casualties in the legislated provinces were also examined relative to the changes in non-occupant casualties and relative to the unlegislated provinces. It was concluded that three provinces experienced some reductions as a result of legislation but not as much as anticipated. It is speculated that the impact of the seat belt use laws fell short of expectations because it was mainly the safe drivers who buckled up in response to the laws.     

The effects of mandatory seat belt legislation on self-reported seat belt use among male and female college students

The effect of seat belt legislation on self-reported seat belt use among male and female college students was investigated. Questionnaires inquiring about seat belt use were administered to college students on three separate occasions: (i) two months prior to the time a mandatory seat belt law went into effect, (ii) two months after the law went into effect, and (iii) 16 months after the law went into effect. Reported seat belt use increased significantly for male and female college students two months after the law took effect. At 16 months postlaw, reported seat belt use remained high for female students but declined almost to the prelaw level for males. Possible reasons offered for these findings are that male college students may be more resistant to having their behavior regulated and, therefore, less likely to internalize changes forced on them, and college-age males may be more inclined to engage in risk-taking behavior than college-age females. The importance of considering males and females separately with respect to seat belt use and interventions designed to increase seat belt use is discussed.     

Primary enforcement seat belt laws are effective even in the face of rising belt use rates

A recent systematic literature review found that primary enforcement laws are more effective at increasing seat belt use than secondary laws in the United States. This report re-examines the studies included in the systematic review to explore whether the benefits of a primary law differ based on: (1) the baseline seat belt use rate; or (2) whether or not the primary law replaces a secondary law. States that directly enacted primary laws showed larger increases in observed seat belt use (median increase of 33 percentage points). These laws were enacted in the mid-1980s, when baseline belt use rates were below 35%. Smaller, but substantial increases in belt use were observed in states that replaced secondary with primary laws (median increase of 14 percentage points). Baseline belt use rates in these states ranged from 47 to 73%. Primary safety belt laws can further increase seat belt use even in states with relatively high baseline levels of belt use.     

Automobile seat belt use in selected countries,states and provinces with and without laws requiring belt use

Belt use in automobiles was observed in 19 cities in five countries. In jurisdictions with belt use laws, belt use ranged from a high of 83% in Sydney, Australia to a low of less than 1% at expressway exits in Japan. Prior to the belt law in Ontario and Quebec, Canada and in the United States without a belt law, belt use ranged from a high of 33% in Los Angeles to a low of 4% in Windsor, Ontario. Persons less than 20 years of age were using belts less often than adults and many people were wearing belts too loosely to be effective in crashes. The 10–20% reductions in deaths in countries with belt laws are not as high as would be expected from the known effects of belts apparently because of the lower usage by those disproportionately involved in severe crashes and because belts are worn improperly.     

Shoulder belt use in four states with belt use laws

Shoulder belt use was observed before and after belt use laws went into effect in New York, New Jersey, Illinois, and Texas. There were large increases in belt use rates in each state in the first month the laws were enforced. In the three states in which post-law observations were made more than once, belt use declined from the levels seen in the first month; rates generally dropped to less than 50 percent. This pattern of decline from initial use rates has also been found in other jurisdictions around the world. Combined enforcement and publicity campaigns have been shown to be capable of reversing this trend and to increase use rates to 65 percent or more. Such campaigns will be needed to maximize the effect of seat belt use laws in the United States.     

Getting Americans to buckle up: the efficacy of state seat belt laws

Annual state observed safety belt use rates over the period 1991–2001 are examined using time-series cross-section regression analysis. It was found that seat belt laws are associated with higher use rates and that the enforcement provision matters. Primary states experience belt use rates that on average are 9.1 percentage points higher than their secondary counterparts. In addition, the level of the fine imposed by statute has an effect on safety belt use apart from that attributable to the enforcement provision. The current median fine of $25 is associated with an additional 3.8 percentage points increase in belt use. To further increase safety belt use, it is recommended that states adopt primary enforcement and impose fines of at least $50 for violating a seat belt law.     

Predicting seat belt use in fatal motor vehicle crashes from observation surveys of belt use

There is a large difference between the rates of observed seat belt use by the general public and belt use by motor vehicle occupants who are fatally injured in crashes. Seat belt use rates of fatally injured occupants, as reported in the Fatality Analysis Reporting System (FARS), are much lower than the use rates found in observation surveys conducted by the states. A series of mathematical models describing the empirical relationship between FARS and observed rates were explored. The initial model was a 'straw man' and used two simplifying assumptions: (a) belt users and nonusers are equally likely to be involved in 'potentially fatal collisions', and (b) belts are 45% effective in preventing deaths. The model was examined by comparing each state's FARS use rate with the predicted rate. The model did not fit the state data points even when possible biases in the data were controlled. We next examined the assumptions in the model. Changing the seat belt effectiveness parameter provided a reasonable fit, but required an assumption that seat belts are 67% effective in preventing fatalities. The inclusion of a risk coefficient for non-belted occupants also provided a reasonable fit between the model and data. A variable risk model produced the best fit with the data. The major finding was that a model consistent with the data can be obtained by incorporating the assumption that nonusers of seat belts have a higher risk of involvement in potentially fatal collisions than do seat belt users. It was concluded that unbelted occupants are over-represented in fatal collisions for two reasons: (a) because of a greater chance of involvement in potentially fatal collisions in the first place, and (b) because they are not afforded the protection of seat belts when a collision does occur.     

Seat belt legislation and seat belt use: effects on differences related to sex, social class and smoking

As part of a larger study of preventive health behavior, 177 adults answered a question about how often they wore seat belts both before and after seat belt legislation was introduced in Britain. Analyses by smoking status, sex and socioeconomic status (SES) showed that all groups increased the frequency of self-reported seat belt use after the law was introduced. Regression analyses showed that before the law, SES, sex and general preventive behavior were significant predictors of seat belt use, while only SES was a significant predictor of post-legislation seat belt use. Overall the results suggested that seat belt legislation was effective in promoting seat belt use since most of the demographic differences were eliminated by the legislation.     

Geographic and sociodemographic variation in self-reported seat belt use in the United States

Background

With new data available, we sought to update existing literature on the prevalence of self-reported seat belt use by state, region, and rural/urban status and to estimate the strength of the association between seat belt use and rural/urban status adjusted for type of seat belt law and several other factors.

Methods

We examined data on self-reported use of seat belts from 50 states, the District of Columbia, and three territories using the 2008 Behavioral Risk Factor Surveillance System, a state-based random-digit-dialed telephone survey (n = 406,552). Reported seat belt use was assessed by state, U.S. Census regions, and U.S. Department of Agriculture (USDA) rural/urban continuum codes.

Results

Overall, 85% of adults in the United States reported they always used seat belts. Regionally, the West had the highest prevalence of persons who reported that they always wear seat belts (89.6%) and the Midwest had the lowest (80.4%). States with primary seat belt laws had the highest prevalence of reported seat belt use, compared with states with secondary or no laws. After adjusting for various sociodemographic characteristics, body mass index, and type of seat belt law, persons in the most densely populated metropolitan areas were significantly more likely to report always wearing seat belts than those in most sparsely populated rural areas (adjusted odds ratio = 2.9).

Conclusion

Our findings reinforce the evidence that primary enforcement seat belt laws are effective for increasing seat belt use, and suggest that upgrading to primary enforcement laws will be an important strategy for reducing crash-related fatalities in rural areas.     

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.     

The effect of New York's seat belt use law on teenage drivers

This study assessed the effects of New York State's recently adopted mandatory seat belt use law on teenage drivers. Teenage drivers were observed as they entered high school parking lots before the law was adopted, after it was adopted but before it was effective, one month after the effective date, and again five months after the effective date. The results showed that 14% of the teenage drivers were wearing either shoulder or lap belts or both prior to adoption of the law. This increased to 22% after adoption of the law, 60% one month after the effective date of the law, and 63% five months after the effective date. Teenagers using seat belts were more often female, were younger, had completed driver education and had a longer trip from home to school. Both before and after the law, teenage belt use was similar to, but typically lower than, belt use in the community in which the school was located.     

Belt use by high-risk drivers before and after New York's seat belt use law

Belt use among drivers traveling on limited access highways was observed before and after New York's mandatory seat belt use law. The results showed that high-speed drivers had lower belt use rates before the law and increased their belt use less in response to the law. Belt use rates before the law were 25%, 29%, and 28% for the high-, medium-, and low-speed groups as compared with 51%, 64%, and 57%, respectively, after the law. High-speed drivers also had inferior previous driving records, confirming their higher risk of motor vehicle crash involvement.     

A joint econometric analysis of seat belt use and crash-related injury severity

This paper formulates a comprehensive econometric structure that recognizes two important issues in crash-related injury severity analysis. First, the impact of a factor on injury severity may be moderated by various observed and unobserved variables specific to an individual or to a crash. Second, seat belt use is likely to be endogenous to injury severity. That is, it is possible that intrinsically unsafe drivers do not wear seat belts and are the ones likely to be involved in high injury severity crashes because of their unsafe driving habits. The preceding issues are considered in the current research effort through the development of a comprehensive model of seat belt use and injury severity that takes the form of a joint correlated random coefficients binary-ordered response system. To our knowledge, this is the first instance of such a model formulation and application not only in the safety analysis literature, but in the econometrics literature in general. The empirical analysis is based on the 2003 General Estimates System (GES) data base. Several types of variables are considered to explain seat belt use and injury severity levels, including driver characteristics, vehicle characteristics, roadway design attributes, environmental factors, and crash characteristics. The results, in addition to confirming the effects of various explanatory variables, also highlight the importance of (a) considering the moderating effects of unobserved individual/crash-related factors on the determinants of injury severity and (b) seat belt use endogeneity. From a policy standpoint, the results suggest that seat belt non-users, when apprehended in the act, should perhaps be subjected to both a fine (to increase the chances that they wear seat belts) as well as mandatory enrollment in a defensive driving course (to attempt to change their aggressive driving behaviors).     

Method to evaluate the effect of safety belt use by rear seat passengers on the injury severity of front seat occupants

Although the effectiveness of seat belts for reducing injury to rear seat passengers in traffic accidents has been well documented, the ratio of rear-seat passengers restrained by seatbelts remains lower than that of drivers or passengers in front seats. If passengers in rear seats do not wear seat belts, they may sustain unexpected injury to themselves when involved in accidents, and also endanger front occupants (drivers or front seat passengers). This paper focuses on the tendency of front seat occupants to sustain severer injuries due to forward movement of passengers in rear seats at the moment of frontal collisions, and evaluates the effectiveness of rear passengers' wearing seat belts in reducing injuries of front seat occupants. Since the occurrence of occupant injuries depends considerably on the crash severity, we proposed to use pseudo-delta V in regression analysis to represent velocity change during a collision when analyzing statistical accident data. As the crash severity can be estimated from pseudo-delta V, it becomes possible to make appropriate estimations even when the crash severity differs in data. The binary model derived from the ordered response model was used to evaluate the influence on the injury level based on pseudo-delta V, belted or unbelted status, gender and age. Occupants in cars with a hood in the case of car-to-car frontal collisions were extracted from the statistical data on accidents in Japan. Among 81,817 cars, where at least one passenger was present, a total of 6847 cars in which all passengers sustained injuries and which had at least one rear seat passenger aboard were analyzed. The number of killed or seriously injured drivers is estimated to decrease by around 25% if rear seat occupants come to wear seat belts. Also, the number of killed or seriously injured passengers in front seats is estimated to decrease by 28% if unbelted rear seat occupants come to wear seat belts. Thus, wearing of seat belts by previously unbelted rear seat passengers is considered effective in reducing not only injuries to the rear seat passengers themselves but also injuries to front seat occupants.     

Sustainability of the effects of the demerit points system on seat belt use: a region-wide before-and-after observational study in Italy

To assess the short and long term effects of the demerit points system on seat belt use, we set a region-wide cross-sectional observational study 3 months before, and 3 and 15 months after the introduction of the scheme (July 2003) in the Veneto Region, Italy. We analysed differences in seat belt use by year of observation, gender and position in the vehicle, and obtained adjusted prevalence ratio (APR) through Poisson regression. A total of 29,303 drivers, 28,778 front and 12,186 rear passengers were observed. Prevalence levels of 54% for drivers and 53% for front passengers in 2003 switched to 83 and 76%, respectively, 3 months after the new legislation, with further slight increases 15 months thereafter. Seventy-four percent rear passengers were still not compliant with the legislation in 2005. The probability of being belted was 25% lower in males than females (APR=0.75, 95% CI 0.73-0.77) at the beginning of the study period. However, the effect of the new legislation was 19% greater among males (APR=1.19, 95% CI 1.16-1.23). A substantial increase in seat belt use was reached and sustained with the demerit points system. Specific efforts should target rear passengers whose seat belt use still remains worryingly low.     

Are there really shortcuts? estimating seat belt use with self-report measures

We examined the utility of estimating rates of automobile seat belt use with selfreport measures. Self-report measures overestimate belt use rates compared to observational surveys of the same population. Laws mandating seat belt use did not substantially affect the degree to which self-reports are upwardly biased. We found self-report measures overestimate observed belt use by 8.9 to 19.4 percentage points or by a factor of 1.2 to 2. Our best estimate is that self-reported seat belt use rates be discounted by 12 percentage points to estimate actual belt use rates.     

Improving seat belt use among teen drivers: Findings from a service-learning approach

Background

Low seat belt use and higher crash rates contribute to persistence of motor vehicle crashes as the leading cause of teenage death. Service-learning has been identified as an important component of public health interventions to improve health behavior.

Methodology

A service-learning intervention was conducted in eleven selected high schools across the United States in the 2011–2012 school year. Direct morning and afternoon observations of seat belt use were used to obtain baseline observations during the fall semester and post-intervention observations in the spring. The Mann–Whitney U test for 2 independent samples was used to evaluate if the intervention was associated with a statistically significant change in seat belt use. We identified factors associated with seat belt use post-intervention using multivariable logistic regression.

Results

Overall seat belt use rate increased by 12.8%, from 70.4% at baseline to 83.2% post-intervention (p < 0.0001). A statistically significant increase in seat belt use was noted among white, black, and Hispanic teen drivers. However, black and Hispanic drivers were still less likely to use seat belts while driving compared to white drivers. Female drivers and drivers who had passengers in their vehicle had increased odds of seat belt use.

Conclusion

A high school service-learning intervention was associated with improved seat belt use regardless of race, ethnicity, or gender, but did not eliminate disparities adversely affecting minority youth. Continuous incorporation of service-learning in high school curricula could benefit quality improvement evaluations aimed at disparities elimination and might improve the safety behavior of emerging youth cohorts.     

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.     

Explaining state-to-state differences in seat belt use: A multivariate analysis of cultural variables

There is considerable variation in seat belt use within the United States despite extensive evidence that the use of seat belts saves lives. Previous studies have identified some important factors that affect belt use rates, including gender, age, race, vehicle type, seat-belt enforcement laws, and amount of fine for belt-use law violation. In this study, we examined the influence of additional socio-demographic factors on state-level use rates: education (percentage of high school educated population), racial composition (percentage White), median household income, political leaning (percentage Democrat), and a measure of religiosity. These variables, which collectively characterize the ‘culture’ of a state, have received little attention in seat-belt studies. The paper reports results from a multiple regression analysis of data from the 2008 Fatality Analysis Reporting System (FARS). Many of the use rate patterns in FARS data were consistent with those found in other data sets, suggesting that conclusions based on FARS data are likely to hold for the population-at-large. Of the five cultural factors considered in the study, three were identified as important in explaining the differences in seat belt use at the state level: religiosity, race (percentage White), and political leaning (percentage Democrat). The other two variables – income and education – were not significant. Hold-out analyses confirmed that this conclusion was consistent across different subsets of data. The findings from this study are preliminary and have to be confirmed on other data sets. Nevertheless, they demonstrate the potential usefulness of cultural factors in explaining state-to-state variation in seat belt use rates. If factors such as religiosity are indeed important, they can be used to develop culturally appropriate programs for increasing belt use.