Evaluation of safety treatments for roadside culverts.

Final report; 2004-2009.PDFTech ReportTRP-03-201-09IHRB TR-517CulvertsHighway safetyBenefit cost analysisRoadsideNebraskaMidwest Roadside Safety FacilityAlbuquerque, Francisco Daniel B.Sicking, Dean L.Lechtenberg, Karla A.Midwest Roadside Safety FacilityIowa. Highway Research BoardUnited States. Federal Highway AdministrationNTL-HIGHWAY/ROAD TRANSPORTATION-Bridges and StructuresNTL-SAFETY AND SECURITY-Highway SafetyNTL-ECONOMICS AND FINANCE-ECONOMICS AND FINANCEUS Transportation CollectionRoadside cross-drainage culverts have been found to impact vehicle accident injury levels.Designers have commonly used three safety treatments to protect errant drivers from culvert accidents.These treatments have included: culvert extension, guardrail installation and grating. In order to definewhich safety treatment is the most appropriate, benefit-cost analysis has used accident cost reduction toestimate societal gains earned by using any safety treatment.The purpose of this study was to estimate accident costs for a wide range of roadway and roadsidecharacteristics so that designers can calculate benefit/cost ratios for culvert safety treatment options underany particular scenario.This study began with conducting a parametric study in order to find variables which havesignificant impact on accident cost changes. The study proceeded with highway scenario modeling whichincluded scenarios with different values for combinations of roadway and roadside variables. Thesevariables were chosen based upon findings from the parametric study and their values were assigned basedupon highway classification. This study shows that the use of different culvert safety treatments should beflexible to roadway and roadside characteristics. It also shows that culvert extension and grating were thesafety treatments found to produce the lowest accident costs for all highway scenarios modeled. Therefore,it is believed that the expanded adoption of culvert extension and culvert grates can improve overallhighway safety