Developing Methodology for Identifying, Evaluating, and Prioritizing Systemic Improvements

Traditional safety improvements have typically been applied in areas based on the number of crashes (i.e., hot or black spot approaches). However, this traditional approach has caused several negative externalities, such as more safety improvement projects are selected at crash condensed urban areas rather than sporadic rural areas. According to Texas Department of Transportation (TxDOT) crash statistics, fatal crashes in rural areas accounted for 55 percent of total fatal collisions in 2011 and 2012. Additionally, there were 1,679 fatal crashes in rural areas in 2012—a 9 percent increase from those reported in 2011. The systemic approach to highway safety improvements focuses on high-risk roadway features, rather than specific high-crash locations, and thus is more effective at reducing fatal/severe injury crashes on rural highways. This report proposes two systemic approaches for the State of Texas, one to project selection and one to roadway characteristic classification. The systemic approach to project selection focuses on reducing the number and severity of target crashes occurring on the TxDOT roadway network, and the approach to roadway characteristic classification deals with developing systemic improvements that focus on a particular countermeasure to have a positive impact on safety. Both approaches include the task to identify the types of preventable crashes that represent the greatest opportunities for reduction. For systemic approach to project selection, those crash types usually represent the greatest number of crashes across the system being analyzed. For the approach to roadway characteristics, those crash types represent the crashes that can be prevented by the countermeasure selected. The next task deals with the identification of risk factors associated with preventable target crash types. In the risk assessment, risk factors are evaluated using the weighting criteria based on the percentages of total crashes and the crash over-representation when compared to the proportion of highway mileage in a particular risk category (e.g. 10 ft lane width). A total risk factor weight calculated based on the total crashes and the crash over-representation is used to prioritize the roadway network locations for countermeasure implementation. The approach to project selection includes a benefit-cost analysis for selecting low-cost, effective countermeasures to remove/alleviate risk factors on roads by adding safety features. This systemic approach is beneficial for addressing not only rural crashes but also crash types less likely clustered in urban areas, particularly those involving pedestrians, bicyclists, and motorcyclists. The systemic approach to roadway characteristic involves identifying low-cost countermeasures for preventable crash types and candidate locations on high-risk rural roadways, as well as defining potential risk factors for preventable crash types. The researchers recommend that countermeasures associated with preventable crash types and roadway risk factors be considered as safety improvements on new highway construction as well as existing highways.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Technical Memorandum
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 94p

Subject/Index Terms

Filing Info

  • Accession Number: 01629711
  • Record Type: Publication
  • Created Date: Mar 22 2017 12:47PM