CMF / CRF Details

CMF ID: 6887

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)
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:Single vehicle
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
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (crashes):131 crashes before, 38 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.