CMF / CRF Details

CMF ID: 4394

Install safety edge treatment

Description: The safety edge is a low-cost treatment that is implemented in conjunction with pavement resurfacing and is intended to help minimize drop-off-related crashes.

Prior Condition:  Rural highways prior to resurfacing and installation of safety edge treatment

Category: Shoulder treatments

Study: Safety Evaluation of the Safety Edge Treatment, Graham et al., 2011

 
Star Quality Rating:4 Stars  [View score details]
Rating Points Total:120
Crash Modification Factor (CMF)
Value:0.575
Adjusted Standard Error:
Unadjusted Standard Error:0.229
Crash Reduction Factor (CRF)
Value:42.488  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:22.855
Applicability
Crash Type:Other
Crash Severity:K (fatal),A (serious injury),B (minor injury),C (possible injury)
Roadway Types:Principal Arterial Other
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:
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
Area Type:Rural
Traffic Volume:Minimum of 1170 to Maximum of 14662 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:1999 to 2008
Municipality:
State:IN
Country:
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (miles):148 miles before, 148 miles after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Dec 06, 2012
Comments:For drop-off-related crashesPaved shoulder study sites 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.