CMF / CRF Details

CMF ID: 9169

Install in-lane curve warning pavement markings

Description: Pavement marking showing the word "Slow" and an arrow to alert drivers to an upcoming curve in the road.

Prior Condition: No Prior Condition(s)

Category: Delineation

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

Image: View the countermeasure image.

Star Quality Rating: 3 Stars   [View score details]
Rating Points Total: 95
Crash Modification Factor (CMF)
Value: 1.67
Adjusted Standard Error:
Unadjusted Standard Error: 0.452
Crash Reduction Factor (CRF)
Value: -67   (This value indicates an increase in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 45.2
Crash Type: Run off road
Crash Severity: All
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:
Traffic Volume: Minimum of 590 to Maximum of 7600 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:
State: IA, PA
Country: USA
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 8 crashes before, 18 crashes after
Sample Size (miles): 0.82 miles before, 0.82 miles after
Sample Size (miles): 8.57 mile-years before, 17.37 mile-years after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Nov-17-2017
Comments: Sample size is small, use with caution. Excludes intersection-related and animal-related crashes.