Investigation of Policy-Based Statewide Safety Measure Quantification

Principal Investigator:

Keith Knapp, Former Research Manager, Humphrey School of Public Affairs

Project Summary:

Many factors that contribute to fatal crashes are related to human behavior. One method of adjusting these behaviors is through the enactment and enforcement of legislatively-based safety improvement measures (LSIMs). The objective of this research was to investigate the feasibility of a research-based rural safety policy improvement index (RSPII) to quantify the state-by-state impacts of LSIMs. Recently completed LSIM summaries categorized the direct safety impacts of 23 behavioral highway safety countermeasures as "proven" with "high-quality" research. It was concluded that a RSPII was feasible and six LSIMs were selected for consideration with a RSPII framework. The LSIMs selected include the implementation of a comprehensive graduated driver licensing program, primary seat belt law, motorcycle helmet use law, sobriety checkpoints, ignition interlocks, and automated speed enforcement. A six-step RSPII framework and a pilot application are documented in the final report. Two estimation methods were used to quantify the rural roadway safety impacts of primary seat belt law implementation. It was estimated that 488 fatalities or 248 unbelted front seat passenger vehicle occupant (at least 13 years old) deaths could be avoided if this were to occur. More detailed applications for all six LSIMs selected will be completed in Phase II of this project.

Six legislatively-based safety improvement measures (LSIMs) were proposed for evaluation within a rural safety policy improvement index (RSPII) framework during Phase I of this project. This report documents the step-by-step application of the RSPII framework and its rural roadway crash fatality reduction results for these LSIMs. Several approaches to the framework application were completed for each LSIM and the results compared. It was estimated (based on the selection of one framework outcome for each LSIM) that rural roadway crash fatalities could be reduced by 209 from the primary enforcement of seat belt use, 299 from universal motorcycle helmet use, 322 from the regular application of sobriety checkpoints, 120 from graduated driver licensing program upgrades, 268 from the mandatory ignition interlock installation, and 699 from automated speed enforcement. These estimates cannot be summed, however, because the fatalities impacted by these LSIMs sometimes overlap. The assumptions and generalizations required to overcome challenges to the RSPII framework application will also have an impact on its results. Additional LSIM research is suggested and it is recommended that the estimates in the final report be used as a starting point for rural roadway safety discussions and the completion of more accurate individual state RSPII framework applications.

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