CMF / CRF Details

CMF ID: 7754

Widen shoulder

Description:

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:3 Stars  [View score details]
Rating Points Total:75
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
Applicability
Crash Type:All
Crash Severity:All
Roadway Types:Not specified
Street Type:
Minimum Number of Lanes:2
Maximum Number of Lanes:
Number of Lanes Direction:
Number of Lanes Comment:> = 2 Lanes
Crash Weather:Not specified
Road Division Type:All
Minimum Speed Limit:45
Maximum Speed Limit:70
Speed Unit:mph
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: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
Municipality:
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 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.