Summary from: Roadway Safety Data Program | Development of Safety Performance Functions for Network Screening in Illinois

Background

In 2006, the Illinois Center for Transportation, Illinois Department of Transportation (IDOT), and the University of Illinois at Urbana-Champaign performed a research project to develop state-specific SPFs to use in the State’s network screening process. Prior to 2006, IDOT used the High Accident Location Identification System (HALIS) to identify High Accident Locations (HAL) and wet pavement cluster/segments that were based on crash frequency, rate, and equivalent property only. This project addressed the following specific challenges:

• linking crash and roadway data, given each had a different linear referencing system;
• establishing the criteria to assign each roadway segment to a peer group;
• using “reference points” to establish intersection locations;
• currency of crash and traffic data;
• processing a large volume of crash and roadway data; and
• helping users understand the meaning of the results.

Read the Case Study Development of Safety Performance Functions for Network Screening in Illinois for more detailed information.