CMF / CRF Details

CMF ID: 7009

Improve pavement friction (Chip Seal)

Description: Chip seal treatment to improve pavement friction

Prior Condition:  No Prior Condition(s)

Category: Roadway

Study: Evaluation of Pavement Safety Performance, Merritt et al., 2015

 
Star Quality Rating:4 Stars  [View score details]
Rating Points Total:130
Crash Modification Factor (CMF)
Value:0.883
Adjusted Standard Error:
Unadjusted Standard Error:0.028
Crash Reduction Factor (CRF)
Value:
Adjusted Standard Error:
Unadjusted Standard Error:
Applicability
Crash Type:Run off road
Crash Severity:All
Roadway Types:Not specified
Street Type:
Minimum Number of Lanes:2
Maximum Number of Lanes:2
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:All
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
Area Type:All
Traffic Volume:Minimum of 170 to Maximum of 24792 Annual Average Daily Traffic (AADT)
Average Traffic Volume:2751 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:
Average Major Road Volume :
Average Minor Road Volume :
Development Details
Date Range of Data Used:2000 to 2011
Municipality:
State:CA,MN,NC,PA
Country:USA
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (miles):2448 miles before, 2448 miles after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Nov 01, 2015
Comments: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.