Development of Crash Modification Factors for Lane Departure Countermeasures

Project status

In progress

Start date: 07/01/14
End date: 10/31/17


Principal investigators:

About the research

Lane departure crashes make up a large percentage of rural crashes for states in the midwest. Since agencies have limited resources, they rely on studies that demonstrate the effectiveness of a particular countermeasure in order to make decisions about which countermeasures should be selected. Most agencies prefer countermeasure effectiveness to be stated in terms of crash modification factors (CMFs) since they are easily understood and commonly used by agencies. Developing data driven performance measures for safety is one of the main MTC themes and robust CMFs have not been developed for a number of lane departure countermeasures.
The objective of this research is to develop CMFs for several lane departure countermeasures that have been used in Iowa. The research includes selecting sites where the countermeasures have been installed, identifying control sites, extracting site characteristics, reducing crash data, conducting analyses, and summarizing results. The team will attempt to develop CMFs for the following countermeasures:

·         Centerline and shoulder rumble strips

·         Cable median barrier

·         Paved shoulders

·         Safety Edge

·         Various expressway intersection countermeasures (as decided by the team and TAC)


Tech transfer summary: Safety Edge Crash Modification Factors Tech Brief (1.29 mb pdf) Dec 2017



  • Federal Highway Administration State Planning and Research Funding
  • Iowa Department of Transportation
  • Midwest Transportation Center