CMF / CRF Details

CMF ID: 6825

Widen shoulder


Prior Condition: Narrower paved shoulder than after condition

Category: Shoulder treatments

Study: Safety Impacts of Highway Shoulder Attributes in Illinois, Bamzai et al., 2011

Star Quality Rating: 3 Stars   [View score details]
Crash Modification Factor (CMF)
Value: 1.51
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value: -51   (This value indicates an increase in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Type: Fixed object,Head on,Run off road,Sideswipe
Crash Severity: A (serious injury),B (minor injury),C (possible injury)
Roadway Types: Principal Arterial Interstate
Number of Lanes:
Road Division Type: Divided by Median
Speed Limit: 65
Area Type: Rural
Traffic Volume:
Average Traffic Volume:
Time of Day: All
If countermeasure is intersection-based
Intersection Type:
Intersection Geometry:
Traffic Control:
Major Road Traffic Volume:
Minor Road Traffic Volume:
Average Major Road Volume : NULL
Average Minor Road Volume : NULL
Development Details
Date Range of Data Used: 2000 to 2006
State: IL
Country: USA
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): NULL crashes
Sample Size (sites): NULL sites
Sample Size (site-years): NULL site-years
Sample Size (miles): NULL miles
Sample Size (mile-years): NULL mile-years
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Jun-22-2015
Comments: This CMF applies to rural interstates with a combined lane width and outside paved shoulder width greater than 20 ft. This CMF applies to shoulder related crashes, defined as head-on, fixed object, sideswipe opposite direction, and run-off-road.