Identification and Assessment of Risks Involved in Operations and Maintenance Activities on Highways: Crash Data Analysis and Development of Severity-Frequency Lists

Mobile operations and highway maintenance work is among the riskiest activities of state highway agencies. Over the past ten years 1,300 fatal-major crashes occurred in Iowa due to mobile operations. Additionally, another 8,234 minor injury crashes, 11,447 possible injury crashes, and 34,038 property damage type of crashes occurred in Iowa in the same time frame (as reported in Iowa DOT crash database). A literature review of risk mitigation of mobile operations in other states has indicated that the topic has been addressed, but typically in very narrow areas (e.g. weather or nighttime operations). Few studies have analyzed risk in moving operations and maintenance (O/M) activities using a system-level analysis. This study provides a broad examination of the different risks that are identified and assessed through expert panel review and analysis of the statewide crash data from 2001 to 2010. A statistical model was developed to identify the significant factors and an analysis of severity and frequency of those factors resulted in development of lists for top ten severe and frequently occurring factors. The combination of these two lists proposed that the Interstate routes and the region located between the advanced warning sign and the work zone are most critical with respect to overall risk. The top ranked five factors from each of the severity and frequency lists were also identified and analyzed.