CMF / CRF Details

CMF ID: 8396

Install w-beam guardrail

Description: Install w-beam guardrail

Prior Condition:  No roadside barrier

Category: Roadside

Study: Evaluation of the Safety Effectiveness of Installing Roadside Barriers with Different Driver, Vehicle, Weather, and Time of Day Conditions, Park et. al., 2016

 
Star Quality Rating:4 Stars  [View score details]
Rating Points Total:130
Crash Modification Factor (CMF)
Value:0.74
Adjusted Standard Error:
Unadjusted Standard Error:0.08
Crash Reduction Factor (CRF)
Value:26  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:8
Applicability
Crash Type:Run off road
Crash Severity:K (fatal),A (serious injury)
Roadway Types:Principal Arterial Other Freeways and Expressways
Street Type:
Minimum Number of Lanes:2
Maximum Number of Lanes:5
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:
Minimum Speed Limit:50
Maximum Speed Limit:70
Speed Unit:mph
Speed Limit Comment:
Area Type:Not specified
Traffic Volume:Minimum of 35000 to Maximum of 104600 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:2003 to 2011
Municipality:
State:FL
Country:
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (sites):127 sites before, 127 sites after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Jan 17, 2017
Comments:CMF is based on a Full Bayes analysis. 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.