The Safety Priority Index System is a method originally developed in 1986 by the Oregon Department of Transportation (ODOT) for identifying potential safety problems on state highways. SPIS complies with the Federal Highway Safety Improvement Program (HSIP) and has been accepted by the Federal Highway Administration (FHWA) as fulfilling the requirements of the HSIP.
When Oregon began developing its Safety Management System in response to the 1991 ISTEA, it identified SPIS as one of several essential building blocks. SPIS has been recognized as an effective problem identification tool for evaluating state highways for segments with higher crash histories.
Several modifications to SPIS have been implemented over the years. Following the study, “An Evaluation of the Safety Priority Index System (SPIS),” completed by Dr. Robert Layton of the Transportation Research Institute at Oregon State University modifications were implemented in the 1998 SPIS reports. In 2005 the programs were rewritten in response to changes to the Crash Database, improvements to the reports were incorporated. It is expected to rewrite the SPIS programs again in 2009 to include all public roads in Oregon (not just state highways).
SPIS Formulation
The basic purpose of the SPIS program is to perform network screening on the state highway network and to identify and prioritize those sites that have promise as sites for potential safety improvements and merit further investigation. The process of conducting detailed engineering studies is an expensive one, therefore, only the sites with the highest ranking (top 5%) are investigated. The best candidates for safety projects will most likely be sites that rank high in terms of safety cost-effectiveness (see the Highway Safety Program Guide for more information on project selection). SPIS Formulation
Each year, a list of the top 10% SPIS sites are generated and the top 5% sites are investigated by the five Region Traffic manager's offices. These sites are evaluated and investigated for safety problems. If a correctable problem is identified, a benefit/cost analysis is performed and appropriate projects are initiated, often with funding from the Highway Safety Improvement Program (HSIP). Regions report the results of their site evaluations to the State Traffic Engineer. These results are incorporated into the Highway Safety Improvement Program (HSIP) 5 percent report to FHWA by August 31 of each year.
Page updated: July 14, 2009
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