Evaluation of the effects of North Carolina's 0.08% BAC law.

This study was conducted to determine whether the lowered BAC limit for drivers in North Carolina resulted in fewer alcohol-related motor vehicle crashes. We used time-series analysis to examine several indicators of alcohol involvement in both injury and fatal crashes between 1991 and 1996. Data from NC crash files as well as the Fatality Analysis Reporting System (FARS) are used. We also examined several indicators used in previous research on lower BAC limits using a before-after design to compare North Carolina with 37 states that did not change their BAC limit for 24 months before and after the BAC limit was lowered. When controlling for the pre-existing downward trend in drinking driver crashes, along with other pertinent factors such as amount of travel and number of weekends per month, there was no evidence of either a significant shift or a change in the downward trend of alcohol-related crashes associated with the lowered BAC limit. In conclusion, although the lower BAC limit was actively enforced and a substantial proportion of drinkers were aware of the new BAC limit, the drinking-driving population in North Carolina, at the time the lower limit took effect in October 1993, was simply unresponsive to this change.

Relationship of parent driving records to the driving records of their children.

Many studies have shown that young driver crash rates can be influenced by such factors as lifestyle characteristics and licensing systems. However, the influence of parents on their teenage children's crash and violation rates has not received much attention. The present study used data from the North Carolina driver history file to match the crash and violation records of young drivers between the ages of 18 and 21 with those of their parents. Results indicate that children's driving records in the first few years of licensure are related to the driving records of their parents. Children whose parents had three or more crashes on their record were 22% more likely to have had at least one crash compared with children whose parents had no crashes. Likewise, children whose parents had three or more violations were 38% more likely to have had a violation compared with children whose parents had none. Logistic regression models showed that these relationships held when controlling for household type and child gender.

The role of driver distraction in crashes: an analysis of 1995-1999 Crashworthiness Data System Data.

Five years (1995-1999) of national Crashworthiness Data System (CDS) data are analyzed to determine the role of driver distraction in traffic crashes and the specific sources of this distraction. Results show that 8.3 percent of the drivers were distracted at the time of their crash; after adjustment for the large percentage of drivers with unknown distraction status, the percentage rose to 12.9 percent. The most frequently cited sources of driver distraction were persons, objects or events outside the vehicle (29.4% of distracted drivers), adjusting the radio, tape or CD player (11.4%), and other occupants in the vehicle (10.9%). Other specific distractions (moving objects in vehicle, other objects brought into vehicle, adjusting vehicle or climate controls, eating and drinking, cell phones, and smoking) were each cited in only one to four percent of the cases. The likelihood of being distracted and the source of distraction varied by driver age but not by gender. Results are discussed in light of the limitations inherent in the CDS and other crash data, and the need for expanded data collection initiatives.

Usage patterns and misuse rates of automatic seat belts by system type.

This study examined seat belt usage in North Carolina by drivers of 4,151 late model cars equipped with a variety of restraint system types. We measured usage by restraint type (automatic belt, air bag, manual belt), by make/model and by driver characteristics (age, sex, and race). Usage ranged from a high of 94.2% for motorized shoulder belts (but with only 28.6% lap belt usage in these cars) to 73.9% usage of manual lap/shoulder belts in cars equipped with air bags. Various types of misuse of the shoulder belt (e.g. excessive slack, detachment from the door, placement under the arm) were observed in nearly 6% of the sample.

The economy as a factor in motor vehicle fatalities, suicides, and homicides.

The effect of the economy as reflected by employment and unemployment rates on motor vehicle fatalities, suicides, and homicides is examined using several national databases. First, regression models are fit to these fatality data-overall as well as for a variety of age-race-gender subgroups. Then time series models-autoregressive integrated moving average (ARIMA) and structural time series analysis-were fit to the data, both with and without the economic indicators, to examine the relative ability of the models to forecast subsequent fatalities. No evidence was found using any of the modeling techniques that knowledge of yearly values of rates of employment, unemployment, and nonlabor force leads to improved forecasts of the level of motor vehicle fatalities, suicides, or homicides in the total U.S. population or within various subpopulations of interest.

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.

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.