Thomas L. Traynor

Regional economic conditions and crash fatality rates - a cross-county analysis

INTRODUCTION Most studies that evaluate the relationship between economic conditions and traffic fatalities focus on the time-series relationship between the two factors. This analysis considers the cross-sectional perspective by estimating the cross-county correlation between per capita income and fatalities per vehicle mile traveled (VMT) in Ohio. METHOD The empirical model employed in this analysis allows for interaction effects between per capita income and highway usage, in the determination of fatality rates. RESULTS The resultant least squares estimates indicate that a significant interaction effect exists between per capita income and the percentage of highway VMT, indicating a nonlinear correlation between per capita income and fatality rates. This correlation rises as the proportion of VMT on highways rises, such that there is an inverse relationship with fatality rates when the highway share of county VMT is low and a direct relationship with fatality rates when the highway share of county VMT is high. Additionally, population density, the presence of interstate highways in rural counties, the prior prevalence of severe alcohol abuse, and the proportion of teen drivers all proved to be significant correlates with county fatality rates. CONCLUSIONS These observations suggest factors that state and federal policy makers should consider when allocating resources that impact (whether directly or indirectly) traffic fatalities.

The Peltzman hypothesis revisited: An isolated evaluation of offsetting driver behavior

Nearly all of the previous investigations of driver behavior under varying safety conditions have only been able to evaluate the issue of offsetting driver behavior indirectly. Some studies note that engineering estimates of the aggregate improvements of automobile safety enhancements are substantively larger than economic estimates of the same effects. Others have found that non-occupants such as motorcyclists and pedestrians are under greater risk of incurring accidents when automobiles are made safer. Although these observations are consistent with the hypothesis that drivers respond to safety enhancements by driving less safely (having been instilled with a sense of greater protection provided by the safety improvements), they do not provide a direct evaluation of the relationship between driving environment and driver behavior. Thus, factors other than offsetting behavior may be generating these observed results. A few studies have tested the offsetting behavior hypothesis more directly, but only under highly specific safety conditions and narrow measures of driver behavior. This article undertakes an isolated analysis of driver behavior under varying safety conditions, with data which allows for more general changes to safety conditions and broader measures of driver behavior. Estimates obtained from the evaluation of individual accident reports lend support to the offsetting behavior hypothesis and imply that both aggressive behavior and nonaggressive (inattentive) driving behavior are likely to increase as the driving environment becomes safer.

The impact of state level behavioral regulations on traffic fatality rates

INTRODUCTION A state by year panel is analyzed to simultaneously explore the statistical correlation between state level traffic fatality rates and state level behavioral regulations regarding teen licensing, seat belt use, and driving under the influence (DUI) in a model that also controls for other correlates. METHOD By including measures of all three of these policies, the estimated policy effects should not be overstated due to underspecification bias. The panel includes the 48 contiguous U.S. states for the time period from 1999 through 2003. State fatality rates are measured as fatalities per million miles traveled. Measures of state policies regarding traffic safety related behavior are based on information gathered by the Insurance Institute for Highway Safety. Estimates are calculated via a time fixed effects model that uses the double-log form to allow for interaction effects between the independent variables. RESULTS Least squares estimates indicate that, on average, more restrictive graduated teen licensing and DUI policies significantly reduce traffic fatality rates, while stricter seat belt enforcement policies have a statistically insignificant negative impact on fatality rates.

The Relationship Between Regional Economic Conditions and the Severity of Traffic Crashes

Objectives: To evaluate the relationship between regional economic conditions and the severity of injury suffered by victims of traffic crashes. This analysis augments the research on the relationship between economic conditions and traffic safety by focusing on injury severity per victim, which isolates the protective effect to individuals from other traffic safety effects such as crashes per mile and aggregate exposure to crashes. Methods: A crash-specific data set from the State of Ohio is used together with county-level economic and demographic data to generate estimates that measure the impact of county-level per capita income and unemployment rate on the severity of injury suffered by each individual who is involved in a crash. The estimates are derived from an ordered probit model that controls for other factors that influence injury severity independently of economic conditions. Results: The resulting estimates indicate that on average, individuals involved in crashes that occur in relatively prosperous counties suffer less severe injuries than those in less prosperous counties, holding other influential factors constant. Regional per capita income has a proportionally greater impact on injury severity than does regional unemployment rate. Conclusions: The estimates indicate that regional economic conditions have a statistically significant beneficial impact on traffic safety by improving the level of injury suffered by crash victims. Therefore, state and federal public policy makers should consider this factor when allocating traffic safety–related resources among geographical regions.

Economic regulation and highway safety in the trucking industry: A limited dependent variable analysis

Abstract The above results lead to the conclusion that economic regulation of the trucking industry does not significantly effect highway safety. Although some of the individual economic variables are not statistically significant, they are consistent in sign throughout all four equations. This is not inconsistent with the concept that economic factors are significant determinants of highway safety. The tests presented in this paper instead evaluated the differential effect of economic factors on trucking safety versus non-truck safety. Also, in all four tests the signs of the key parameter (for regulatory change) are in the direction that indicates a positive relationship between reduced regulation and highway safety. These results are not necessarily inconsistent with other studies which show that imminent bankruptcy is a detriment to highway safety. Our results imply that if this is the case, it is not prevalent enough throughout the entire trucking industry to cause a significant change to total trucking safety or total highway safety. As the theoretical discussion implies, regulatory change could either improve or hinder highway safety depending on the relative magnitude of its effects on market price and carriage restrictions. An appeal to empirical evidence suggests that these factors netted out, and regulatory change did not have a statistically significant effect on highway safety. These tests provide valuable insight into the relationship between regulation and highway safety. Most tests until now only analyzed the profit-safety relationship, and therefore did not take into account other factors that are important to highway safety. As a final point, this analysis has theoretically motivated and empirically tested hypotheses concerning the net effect of economic regulation on highway safety. Unfortunately, data limitations prevented us from testing more detailed hypotheses on the underlying processes which link the two phenomena. Fruitful areas for future research would analyze the effects of specific aspects of regulatory legislation, such as operating restrictions and price controls, on per mile accident rates.

The impact of safety regulations on externalities

Empirical analyses of product safety regulations have indicated that such regulations induce compensating behavior (also known as offsetting behavior) by the users of products that pose risks to their health. Many of these analyses conclude that such compensating behavior causes externalities to rise. In such cases, regulations reduce the loss suffered by the user of the good when a harmful event occurs, encouraging a moral hazard response which creates externalities for others. Other studies find that although compensating behavior mitigates the beneficial impact of safety regulations, such externalities do not rise. This paper presents a model suggesting that although compensating behavior always occurs in response to product safety regulations, a dichotomy exists wherein regulations engineered to reduce the typical loss suffered by individuals per accident (or loss event) will increase externalities, while regulations engineered to reduce the number of accidents (or loss events) will reduce externalities.

Trucking Deregulation and Highway Safety – The Effect of the 1980 Motor Carrier Act

The relationship between deregulation in the trucking industry and highway safety is an important economic and social issue. Analyses thus far have concentrated on the relationship between the downward pressure imposed on freight rates by deregulation and total safety investment by firms. Two issues which have been ignored are the effects that deregulation had on route carriage restrictions and total firm mileage. We show that the inclusion of these factors yields a model in which the relationship between motor carrier deregulation and highway safety is dependent upon the relative effects of all three factors. Estimation of the model using accident data implies that trucking deregulation did not deteriorate highway safety and may have actually improved it.