Statistical Analysis of Safety Improvements and Integration Into Project Design Process

US Transportation Collectionhttps://doi.org/10.5703/12882843171212020PDFTech ReportTarko, Andrew P.Romero, MarioLizarazo, CristhianPineda, RaulPurdue University. Joint Transportation Research ProgramIndiana. Dept. of TransportationUnited States. Department of Transportation. Federal Highway AdministrationPurdue University. Joint Transportation Research ProgramIndianaUnited StatesCountermeasuresCrash modification factorsCrash ratesEconomic impactsImprovementsPerformance measurementSafety managementSoftwareStatistical analysisRoadway safetyScoping projectFHWA/IN/JTRP-2020/09SPR-4216Final ReportRoadHAT is a tool developed by the Center for Road Safety and implemented for the INDOT safety management practice to help identify both safety needs and relevant road improvements. This study has modified the tool to facilitate a quick and convenient comparison of various design alternatives in the preliminary design stage for scoping small and medium safety-improvement projects. The modified RoadHAT 4D incorporates a statistical estimation of the Crash Reduction Factors based on a before-and-after analysis of multiple treated and control sites with EB correction for the regression-to-mean effect. The new version also includes the updated Safety Performance Functions, revised average costs of crashes, and the comprehensive table of Crash Modification Factors\u2014all updated to reflect current Indiana conditions. The documentation includes updated Guidelines for Roadway Safety Improvements. The improved tool will be implemented at a sequence of workshops for the final end users and preceded with a beta-testing phase involving a small group of INDOT engineers.110