CMF / CRF Details

CMF ID: 4203

Increase yellow interval and add all red interval

Description: The average increase in the yellow time was 0.8 seconds (minimum of 0.5 sec and maximum of 1.6 sec). The average increase in the all red interval was 1.2 seconds (minimum of 1.0 sec and maximum of 2.0 sec).

Prior Condition:  Signalized intersection with yellow interval and no all red interval. The average increases in the yellow and all red times were 0.8 seconds (minimum of 0.5 seconds and maximum of 1.6 seconds) and 1.2 seconds (minimum of 1.0 second and maximum of 2.0 seconds), respectively.

Category: Intersection traffic control

Study: Evaluation of Safety Strategies at Signalized Intersections, Srinivasan, et al., 2011

Star Quality Rating:3 Stars  [View score details]
Rating Points Total:90
Crash Modification Factor (CMF)
Adjusted Standard Error:
Unadjusted Standard Error:0.146
Crash Reduction Factor (CRF)
Value:1  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:14.6
Crash Type:All
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:Urban
Traffic Volume:
Average Traffic Volume:
Time of Day:All
If countermeasure is intersection-based
Intersection Type:Roadway/roadway (not interchange related)
Intersection Geometry:3-leg,4-leg
Traffic Control:Signalized
Major Road Traffic Volume:Minimum of 5950 to Maximum of 31600 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume:Minimum of 2650 to Maximum of 20225 Annual Average Daily Traffic (AADT)
Average Major Road Volume :17417 Annual Average Daily Traffic (AADT)
Average Minor Road Volume :8484 Annual Average Daily Traffic (AADT)
Development Details
Date Range of Data Used:1992 to 2002
Municipality:San Diego, San Francisco, Howard County, and Montgomery County
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (sites):11 sites after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Dec 06, 2012
Comments:Assumed 2 crashes per site in both the before and after periods to estimate sample size.