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.