CMF / CRF Details

CMF ID: 4920

Install a "Vehicles Entering When Flashing" (VEWF) system (combination of overhead and advance post mounted signs)

Description: Safety effectiveness of "Vehicle Entering When Flashing" (VEWF) intersection conflict warning systems at stop-controlled intersections

Prior Condition: stop-controlled

Category: Signs

Study: Evaluation of the Safety Effectiveness of "Vehicle Entering When Flashing" Signs and Actuated Flashers at 74 Stop-Controlled Intersections in North Carolina, Simpson and Troy, 2013

Star Quality Rating: 3 Stars   [View score details]
Rating Points Total: 105
Crash Modification Factor (CMF)
Value: 0.75
Adjusted Standard Error:
Unadjusted Standard Error: 0.115
Crash Reduction Factor (CRF)
Value: 25   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 11.5
Crash Type: All
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:
Minimum Speed Limit: 45
Maximum Speed Limit: 55
Speed Unit: mph
Speed Limit Comment:
Area Type: All
Traffic Volume:
Average Traffic Volume:
Time of Day:
If countermeasure is intersection-based
Intersection Type: Roadway/roadway (not interchange related)
Intersection Geometry: 4-leg
Traffic Control: Stop-controlled
Major Road Traffic Volume: Minimum of 3000 to Maximum of 30000 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume:
Average Major Road Volume :
Average Minor Road Volume :
Development Details
Date Range of Data Used: 1996 to 2010
State: NC
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 67 crashes after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Aug-01-2013
Comments: A linear assumption was used to account for changes in traffic volume at the treatment sites (instead of SPFs).