Development of a Methodology to Evaluate the Highway Safety Improvement Program

The goal of this research study was to provide information and develop tools that can help the Idaho Transportation Department (ITD) conduct safety effectiveness evaluation consistently across the state, provide data-driven rationale for future investments, and to help prepare the evaluation section of the Highway Safety Improvement Program (HSIP) Annual Report. A method and a geographic information system (GIS) tool were developed to evaluate the safety effectiveness of individual projects and groups of projects. The tool uses readily available data to calculate four safety performance measures: crash frequency, crash rate, annual economic cost, and severe crash proportion. The tool output includes: an Excel file with safety performance measure data; GIS files for mapping the crash data; and a report that provides tables and charts for the safety performance measures, a Google Street View image, and crash map. In the future, ITD could implement the process through a different platform, such a web application, or modify the GIS tool for future needs. A case study evaluation was done for nineteen HSIP projects that were completed between 2014 and 2016