CMF / CRF Details

CMF ID: 7730

Install left turn flashing yellow arrow signals and supplemental traffic signs

Description: Install left turn flashing yellow arrow signals with supplemental traffic signs with text "Left Turn Yield on Flashing Yellow Arrow"

Prior Condition:  Permissive phase of the PPLT control operated with a circular green indication

Category: Intersection traffic control

Study: Safety Effects of Traffic Signing for Left Turn Flashing Yellow Arrow Signals, Schattler et al., 2015

Star Quality Rating:4 Stars  [View score details]
Rating Points Total:120
Crash Modification Factor (CMF)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value:14.3  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Type:Left turn
Crash Severity:All
Roadway Types:All
Street Type:
Minimum Number of Lanes:2
Maximum Number of Lanes:7
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:All
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:
Intersection Geometry:3-leg,4-leg
Traffic Control:Signalized
Major Road Traffic Volume:Minimum of 3250 to Maximum of 37500 Average Daily Traffic (ADT)
Minor Road Traffic Volume:Minimum of 63 to Maximum of 14700 Average Daily Traffic (ADT)
Average Major Road Volume :17215 Average Daily Traffic (ADT)
Average Minor Road Volume :4576 Average Daily Traffic (ADT)
Development Details
Date Range of Data Used:2007 to 2013
Type of Methodology Used:Before/after using empirical Bayes or full Bayes
Sample Size (crashes):216 crashes before, 52.62 crashes after
Sample Size (sites):90 sites before, 90 sites after
Sample Size (site-years):270 site-years before
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Mar 08, 2016
Comments:CMFs of left-turn related crashed on signalized intersections, including not interchange related and interchange related intersections. Applies to approaches with dedicated left turn lanes and PPLT phasing before and after.