CMF / CRF Details

CMF ID: 7766

Install shoulder rumble strips and widen shoulder width

Description: A combination of adding shoulder rumble strips and widening shoulder width

Prior Condition: Roadways without shoulder rumble strips and 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]
Rating Points Total: 60
Crash Modification Factor (CMF)
Value: 0.4
Adjusted Standard Error:
Unadjusted Standard Error: 0.08
Crash Reduction Factor (CRF)
Value: 60   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 8
Crash Type: Run off road
Crash Severity: All
Roadway Types: All
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)
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 :
Average Minor Road Volume :
Development Details
Date Range of Data Used: 2005 to 2010
State: FL
Country: USA
Type of Methodology Used: 1
Sample Size (sites): 30 sites before, 30 sites after
Sample Size (site-years): 60 site-years before, 60 site-years after
Sample Size (miles): 122 miles before, 122 miles after
Sample Size (miles): 244 mile-years before, 244 mile-years after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Mar-08-2016
Comments: CMFs of installing shoulder rumble strips and widening shoulder width on rural multi-lane highways apply to single-vehicle run-off-road crashes The number of crashes in the after period were not reported in this study, however, they have been recorded as 300 to give 10 points as a beneift of doubt for one or more of the following: (1) number of miles/sites in the reference/treatment group, (2) number of crashes in the references/treatment group, (3) reporting AADTs for the aggregate dataset but not for the disaggragate dataset used for CMF development.