Highway Safety Policy Research Articles

Development of Highway Safety Policies by Discriminating Freeway Curve Alignment Features

In the Republic of Korea, severe crashes with injuries and fatalities have most frequently occurred in freeway sections with combinations of horizontal and vertical curves. To address this issue related to geometric complexness, this study quantitatively verified the adequacy of Korean highway safety policy and identified supplemental strategies required for the freeway sections with horizontal and vertical curve combinations. Based on in-depth road geometric data, this study combined K-means clustering with binomial logit regression to identify the effects of contributing factors on cluster-based crash severity levels. Resultantly, six clusterbased crash severity estimation models were produced. Single vehicle to roadside protective facility and multivehicle crash types were significant to decrease the likelihood of injury crashes for both full-and three cluster-based regression models. Compared with full data model, driver’s age, action, crash occurrence time, and traffic management related factors were significantly identified in only single cluster. The resultant findings show that multidirectional highway safety policies are further required for the current Korean highway safety policy associated with curve alignment features. This study will assist in researchers and field practitioners’ decision-making for future cost-effective highway safety policies provision related to freeway sections with geometric complexness.

Drugged driving: increased traffic risks involving licit and illicit substances.

Driving under the influence of drugs poses risks for traffic safety. Most research attention has been focused on the most prevalent drugs of abuse, such as alcohol, illegal drugs, and prescription drugs with high abuse potential. The objectives of this study were to determine the types of drugs used by convicted DUI offenders on the day of their arrest, prevalence of poly-substance use, and offender characteristics associated with different drug use patterns. Data were collected from 6,339 individuals enrolled in the court-mandated Mississippi Alcohol Safety Education Program. After alcohol, cannabis was the most frequently used substance, followed by sedative medications and prescription analgesics. Among poly-substance users, 78.4% reported combining alcohol with other drugs. Findings could be used to inform public education campaigns, law enforcement training, and highway safety policies about the prevalence of combining alcohol with other drugs, as well as how poly-substance use further impairs traffic-related risks.

Public Perceptions of Pricing Existing Roads and Other Transportation Policies: The Texas Perspective

This work illuminates public opinion on various transportation policies and issues. Statewide survey results reveal considerable agreement on two issues (higher tolls for heavy vehicles and dedicated truck lanes) and reasonable support for conversion of non-tolled roads to tolled roads. Under congestion pricing, older persons report being more likely to reduce their travel during peak periods, members of larger households are more likely to change travel routes, and full-time workers are more likely not to change their current travel patterns. Other results tie into the information content of messages, highway safety policies and revenue generation for transportation agencies.

Use and Misuse of Motor-Vehicle Crash Death Rates in Assessing Highway-Safety Performance

Objectives. The objectives of the article are to assess the extent to which comparisons of motor-vehicle crash death rates can be used to determine the effectiveness of highway-safety policies over time in a country or to compare policy effectiveness across countries. Methods. Motor-vehicle crash death rates per mile traveled in the 50 U.S. states from 1980 to 2003 are used to show the influence on these rates of factors independent of highway-safety interventions. Multiple regression models relating state death rates to various measures related to urbanization and demographics are used. Results. The analyses demonstrate strong relationships between state death rates and urbanization and demographics. Almost 60% of the variability among the state death rates can be explained by the independent variables in the multiple regression models. When the death rates for passenger vehicle occupants (i.e., excluding motorcycle, pedestrian, and other deaths) are used in the regression models, almost 70% of the variability in the rates can be explained by urbanization and demographics. Conclusions. The analyses presented in the article demonstrate that motor-vehicle crash death rates are strongly influenced by factors unrelated to highway-safety countermeasures. Overall death rates should not be used as a basis for judging the effectiveness (or ineffectiveness) of specific highway-safety countermeasures or to assess overall highway-safety policies, especially across jurisdictions. There can be no substitute for the use of carefully designed scientific evaluations of highway-safety interventions that use outcome measures directly related to the intervention; e.g., motorcyclist deaths should be used to assess the effectiveness of motorcycle helmet laws. While this may seem obvious, there are numerous examples in the literature of death rates from all crashes being used to assess the effectiveness of interventions aimed at specific subsets of crashes.

Buckle up or Slow down? New Estimates of Offsetting Behavior and Their Implications for Automobile Safety Regulation

This study provides a detailed examination of the determinants of motor vehicle fatalities and offers a new assessment of the effects of automobile safety regulation. An empirical analysis is difficult because drivers are unlikely to remain passive in the face of changes in their safety environment. This offsetting behavior hypothesis is cast in a broad framework that brings together elements from the economics and cognition literatures. This approach allows us to highlight key maintained assumptions in previous analyses and to consider how econometric evidence can inform discussions about highway safety policy. The econometric estimates reveal that, while imprecisely estimated, offsetting behavior is quantitatively important and attenuates the effects of safety regulation on total motor vehicle fatalities. Cognitive elements, the relative costs of repairs, and the functional form of the estimating equation are shown to play prominent roles in the analysis of safety regulation. Our estimates imply that current highway policy initiatives—mandating restraint systems and relaxing restrictions on the maximum speed limit—are likely to have only a modest net effect on reducing motor vehicle fatalities.

Effects of child restraint laws on traffic fatalities in Eleven States

Mandatory child restraint laws in 11 states were evaluated for their effect on motor vehicle fatality rates among young children. Data from 1976 through 1983 were analyzed using a monthly time-series design involving 54 months' pre-law and 12 months' post-law data. The 11 states collectively had a mean of 8.8 and a standard deviation of 3.6 fatalities per month among young children. Such small frequency counts resulted in a large proportion of the variation being random. Statistical power analyses found fatality reductions of 20% to 25% following the child restraint laws would be statistically significant. Reductions of such a magnitude were not found for young children. Based on these findings, we recommend that evaluations of highway safety policies focusing on a specific age group within a single state not be limited to analyses of traffic fatalities alone. Studies employing analyses of the larger numbers of crash-induced injuries have identified modest but important casualty reductions not found when analyzing fatalities alone.

Effects of child restraint laws on traffic fatalities in eleven states.

Mandatory child restraint laws in 11 states were evaluated for their effect on motor vehicle fatality rates among young children. Data from 1976 through 1983 were analyzed using a monthly time-series design involving 54 months' pre-law and 12 months' post-law data. The 11 states collectively had a mean of 8.8 and a standard deviation of 3.6 fatalities per month among young children. Such small frequency counts resulted in a large proportion of the variation being random. Statistical power analyses found fatality reductions of 20% to 25% following the child restraint laws would be statistically significant. Reductions of such a magnitude were not found for young children. Based on these findings, we recommend that evaluations of highway safety policies focusing on a specific age group within a single state not be limited to analyses of traffic fatalities alone. Studies employing analyses of the larger numbers of crash-induced injuries have identified modest but important casualty reductions not found when analyzing fatalities alone.

Quantitative analysis of policy decisions

The use of quantitative models for highway safety policy analysis is discussed. The importance of interaction between managers and model analysts is emphasized for the development and application of these models. Two examples are presented. First, the trade-off between injury cost and fuel savings as a function of vehicle weight reduction is analyzed. Second, passive restraint effectiveness and its interaction with vehicle size is studied.

A critical analysis of federal highway safety policy

The contention that is examined and documented in the following article is that the most critical issues in highway safety throughout the world are policy-related; that is, solutions are dependent upon policy commitments to achieve an optimum balance between risk, resources and mobility. Emphases on purely technological solutions and upon actions derived from emotional, intuitive policies are leading to large expenditures and disappointing results. For the 1966–1971 period, increases in expenditures for highway safety in the United States have been in the order of $10–$20 billion. Most of these costs have been borne by the highway user, not through taxation but through executive action based upon the 1966 Highway Safety Acts. While the fatality rate is lower per hundred-million vehicle-miles of travel, the total annual number killed on U.S. highways has increased from 53,000 to 56,000 from 1966 to 1972. A type of cost effectiveness approach is suggested, based upon specific policy goals in terms of maximum annual fatalities, available resources and desired mobility. It is argued that for a given level of resources, the greatest reduction in fatalities will be derived if funds are used to implement corrective measures that have the lowest cost per life saved.