Donald W. Reinfurt

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 childrens 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 childrens 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.

Increasing seat belt use in North Carolina

North Carolina has embarked on an ambitious multiyear program designed to increase seat belt and child restraint use and to reduce other traffic law violations, including alcohol-impaired driving. Increasing seat belt use, based on the Canadian model of a combination of intensive enforcement and publicity about the enforcement, was emphasized during the first phase. The program called “Click It or Ticket,” was implemented in October and November 1993 and followed up with a second enforcement blitz in July 1994. In all, 6,364 seat belt checkpoints were held, and 58,883 citations for not using belts along with 3,728 citations for not using child safety seats were issued at these checkpoints and by patrols. Driver belt use increased from 64% before the program to 80% in November 1993, dropped to 73% by May 1994, and then rose slightly higher to 81% in August 1994. Based on time-series analyses, it is estimated that 45 more fatalities and 320 additional serious injuries would have occurred during the 6 months following the program than were actually observed. Using a model based on the costs of medical care and emergency services, these estimated injury reductions translate to medical care cost savings of more than

Development of the bicycle compatibility index

7 million. To gauge public knowledge and opinion, several random digit telephone surveys were carried out following the two program blitzes. At least 75% of the respondents were aware of the program, and more than 85% of the total sample were in favor of such programs.

The analysis of categorical data from mixed models

Presently, there is no methodology that is widely accepted by engineers, planners, or bicycle coordinators that will allow them to determine how compatible a roadway is for allowing efficient operation of both bicycles and motor vehicles. Determining how existing traffic operations and geometric conditions affect a bicyclist’s decision to use or not use a specific roadway is the first step in determining the bicycle compatibility of the roadway. The Federal Highway Administration sponsored a study in which a methodology for deriving a bicycle compatibility index was developed. This tool can be used by bicycle coordinators, transportation planners, traffic engineers, and others to evaluate the capability of specific roadways to accommodate both motorists and bicyclists. It is intended to provide practitioners with the ability to assess the bicycle level of service present on existing facilities or on proposed facilities and can be used for operational, design, and planning analyses.

CHARACTERISTICS OF DRIVERS NOT USING SEAT BELTS IN A HIGH BELT USE STATE

This paper is concerned with contingency tables which are analogous to the well-known mixed model in analysis of variance. The corresponding experimental situation involves exposing each of n subjects to each of the d levels of a given factor and classifying the d responses into one of r categories. The resulting data are represented in an r X r X ... X r contingency table of d dimensions. The hypothesis of priincipal interest is equality of the one-dimensioinal marginal distributions. Alternatively, if the r categories may be quantitatively scaled, then attention is directed at the hypothesis of equality of the mean scores over the d first order marginals. Test statistics are developed in terms of minimum Neyman X2 or equivalently weighted least squares analysis of underlying linear models. As such, they bear a strong resemblance to the Hotelling T2 procedures used with continuous data in mixed models. Several numerical examples are given to illustrate the use of the various methods discussed.

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

A study was undertaken in North Carolina to determine the characteristics of the minority of drivers who were not using seat belts following an extensive publicity/enforcement campaign, which had increased statewide use to 80%. Vehicles and drivers whose seat belt use was observed at sites across North Carolina were matched against Division of Motor Vehicles registration and driver history files for vehicle owners. The study file consisted of those observed drivers who matched the owners with respect to sex, race, and approximate age. The results of this investigation indicate that nonuse of seat belts was associated with males; younger age (<35); older vehicles (pre-1985); vehicles other than cars, especially pickups; and poor driving records. Telephone survey information indicated that nonusers were less likely to have health care coverage, more likely to acknowledge having consumed large amounts of alcohol in the past year, and more likely to have an arrest record. When asked about enforcement of the belt use law, many nonusers said that they would not respond to higher fines but they would respond to driver license points. To change the belt use behavior of this hard-core nonuser population, it well may be necessary as was done in Canada to combine publicity/enforcement campaigns with driver license points as a penalty for nonuse.

Evaluating the North Carolina safety belt wearing 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.

CHANGE IN INJURIES ASSOCIATED WITH SAFETY BELT LAWS

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

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.

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

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.