CMF / CRF Details

CMF ID: 8980

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: 4 Stars   [View score details]
Rating Points Total: 110
Crash Modification Factor (CMF)
Value: 0.731
Adjusted Standard Error:
Unadjusted Standard Error: 0.17
Crash Reduction Factor (CRF)
Value: 26.9   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 17
Crash Type: Nighttime
Crash Severity: All
Roadway Types: Not specified
Number of Lanes:
Road Division Type:
Speed Limit:
Area Type: Not specified
Traffic Volume: Minimum of 173 to Maximum of 27235 Annual Average Daily Traffic (AADT)
Average Traffic Volume:
Time of Day: Night
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:
State: IA, KS, MO
Country: USA
Type of Methodology Used: 2
Sample Size (crashes): 206 crashes before, 85 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