CMF / CRF Details

CMF ID: 6885

Install dynamic speed feedback sign

Description: System consisting of a speed measuring device and a message sign that displays feedback to those drivers who exceed a predetermined threshold. It may be the actual speed, a message such as SLOW DOWN, or activation of a warning device, such as beacons or a curve warning sign

Prior Condition: High-crash curve sites with identified speeding problem

Category: Advanced technology and ITS

Study: Evaluation of Dynamic Speed Feedback Signs on Curves: A National Demonstration Project, Hallmark et al., 2015

Star Quality Rating: 4 Stars   [View score details]
Rating Points Total: 110
Crash Modification Factor (CMF)
Value: 0.95
Adjusted Standard Error:
Unadjusted Standard Error: 0.01
Crash Reduction Factor (CRF)
Value: 5   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 1
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: Undivided
Minimum Speed Limit: 50
Maximum Speed Limit: 65
Speed Unit: mph
Speed Limit Comment:
Area Type: Rural
Traffic Volume: Minimum of 400 to Maximum of 8400 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: 2005 to 2013
State: AZ, FL, IA, OH, OR, TX, WA
Country: USA
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 160 crashes before, 53 crashes after
Sample Size (sites): 20 sites before, 20 sites after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Nov-01-2015
Comments: This CMF applies to two-lane rural horizontal curves.