CMF / CRF Details

CMF ID: 6663

Widen shoulder

Description:

Prior Condition: Original shoulder width 8-12 ft

Category: Shoulder treatments

Study: Exploration and comparison of crash modification factors for multiple treatments on rural multilane roadways, Park et al., 2014

 
Star Quality Rating: 2 Stars   [View score details]
Rating Points Total: 70
Crash Modification Factor (CMF)
Value: 0.817
Adjusted Standard Error:
Unadjusted Standard Error: 0.068
Crash Reduction Factor (CRF)
Value: 18.3   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 6.8
Applicability
Crash Type: All
Crash Severity: All
Roadway Types: Not specified
Street Type:
Minimum Number of Lanes: 3
Maximum Number of Lanes:
Number of Lanes Direction: Both Directions
Number of Lanes Comment: Multi Lane
Crash Weather: Not specified
Road Division Type:
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
Area Type: Rural
Traffic Volume: Minimum of 2000 to Maximum of 50000 Annual Average Daily Traffic (AADT)
Average Traffic Volume:
Time of Day:
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: 2003 to 2012
Municipality:
State: FL
Country:
Type of Methodology Used: Other before/after
Sample Size (sites): 31 sites before
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Jun-22-2015
Comments: Before condition shoulder width between 8-12 ft. Study method was either EB or CG, the authors chose the method that had the lowest SE. 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.