CMF / CRF Details

CMF ID: 7754

Widen shoulder


Prior Condition: Roadways with narrow shoulders

Category: Shoulder treatments

Study: Validation and Application of Highway Safety Manual (Part D) in Florida, Abdel-Aty et al., 2014

Star Quality Rating: 2 Stars   [View score details]
Crash Modification Factor (CMF)
Value: 0.82
Adjusted Standard Error:
Unadjusted Standard Error: 0.09
Crash Reduction Factor (CRF)
Value: 18 (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 9
Crash Type: All
Crash Severity: All
Roadway Types: Not specified
Number of Lanes: >2
Road Division Type: All
Speed Limit: 45-70
Area Type: Rural
Traffic Volume: Minimum of 2000 to Maximum of 50000 Annual Average Daily Traffic (AADT)
Time of Day: All
If countermeasure is intersection-based
Intersection Type:
Intersection Geometry:
Traffic Control:
Major Road Traffic Volume:
Minor Road Traffic Volume:
Development Details
Date Range of Data Used: 2005 to 2010
State: FL
Country: USA
Type of Methodology Used: Before/after using comparison group
Sample Size (sites): 30 sites before, 30 sites after
Sample Size (site-years): 60 site-years before, 60 site-years after
Sample Size (miles): 102.07 miles before, 102.07 miles after
Sample Size (miles): 204 mile-years before, 204 mile-years after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Mar-08-2016
Comments: CMFs of widening shoulder width on rural multi-lane highways

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The information contained in the Crash Modification Factors (CMF) Clearinghouse is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in the CMF Clearinghouse. The information contained in the CMF Clearinghouse does not constitute a standard, specification, or regulation, nor is it a substitute for sound engineering judgment.