CMF / CRF Details

CMF ID: 8978

Install oversized chevron signs

Description: Curve warning treatment with oversized chevron signs

Prior Condition:  smaller 12x18in or 24x30in signs

Category: Signs

Study: Safety Evaluation of Two Curve Warning Treatments: In-Lane Curve Warning Pavement Markings and Oversized Chevron Signs, Lyon et al., 2017

 
Star Quality Rating:3 Stars  [View score details]
Rating Points Total:105
Crash Modification Factor (CMF)
Value:0.852
Adjusted Standard Error:
Unadjusted Standard Error:0.189
Crash Reduction Factor (CRF)
Value:14.8  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:18.9
Applicability
Crash Type:All
Crash Severity:K (fatal),A (serious injury),B (minor injury),C (possible injury)
Roadway Types:Not specified
Street Type:
Minimum Number of Lanes:
Maximum Number of Lanes:
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:Not specified
Traffic Volume:Minimum of 173 to Maximum of 27235 Annual Average Daily Traffic (AADT)
Average Traffic Volume:
Time of Day:Not specified
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:
Municipality:
State:IA,KS,MO
Country:USA
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (crashes):259 crashes before, 109 crashes after
Sample Size (sites):91 sites before, 91 sites after
Sample Size (miles):19.57 miles before, 19.57 miles after
Sample Size (miles):223.25 mile-years before, 139.36 mile-years after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Nov 17, 2017
Comments:Small sample size, use with caution