Methods to Identify Needed Highway Safety Improvements in South Dakota

US Transportation Collection2011PDFTech ReportWemple, ElizabethDePencier, DarrylJin, LiFranca, DiegoRuiz, ChrissMonsere, ChristopherKittelson & Associates, IncPortland State UniversitySouth Dakota. Dept. of Transportation. Office of ResearchUnited States. Department of Transportation. Federal Highway AdministrationSouth Dakota. Dept. of Transportation. Office of ResearchSouth DakotaUnited StatesHighway safetyCrash analysisGeographic information systemsNetworksResearchMethodologyEvaluationUrban areasHighway Safety Crash Analysis ToolPrioritizationNetwork screeningSD2009-07-F311087Final Report January 2009 to March 2011The South Dakota Department of Transportation (SDDOT) sought to develop a network screening program to proactively identify locations where potential crash frequency can be reduced, and for prioritizing improvements based on maximizing system safety benefits within budget constraints. This program also needs to respond to SDDOT\u2019s challenge of being unable to fully invest its safety funding, and to invest in the most worthwhile manner. In order to respond to these needs, the Research Team conducted several tasks including the review of national and state literature, the evaluation of the existing prioritization process, the identification of roadway and crash data available, and the analysis of alternative methodologies. The findings of these tasks identified the need, among other things, of an improved performance measure for analyzing crashes along segments and intersections. For the data currently available in South Dakota, the Excess Proportion of Specific Crash Type was recommended as the new performance measure. A high crash location analysis was found to be appropriate to address safety prioritization on urban locations, while a high crash location and systematic crash analysis was found to be more appropriate for rural locations. A GIS-based tool called Crash Analysis Tool was developed by the team to aid the application of the proposed methodologies. The main recommendations of the research project are: (1) for urban environments, adopt the excess proportion method as applied in the Crash Analysis Tool as a performance measure for identifying high crash locations, and (2) for rural environments, adopt the excess proportion method as applied in the Crash Analysis Tool for identifying sites with potential for safety improvements, and adopt the systematic method as a means for identifying treatments for programmatic implementation. Additional recommendations related to data needs, funding, and program evaluation are also part of the research project.143