Study Details

Study Title: Flashing Yellow Arrow Signal Safety Evaluation

Authors: Storm et al.

Publication Date:NOV, 2020

Abstract: The Minnesota Department of Transportation (MnDOT) requested a high-level comparison of the safety performance of flashing yellow arrow (FYA) signal heads in Minnesota and FYA signal heads studied in other states. A literature review was performed on the Crash Modification Factor (CMF) Clearinghouse for FYA CMFs, which showed decreases in crashes for converting protected-permissive and permissive only signals to FYA, and increases in crashes for converting protected-only signals to FYA. A naïve before-after analysis was performed to estimate Minnesota CMFs for converting protected-permissive, permissive-only, and protected-only signals to FYA signals. Though a naïve before-after analysis does not control for potential bias due to regression to the mean, the analysis used a linear adjustment to control for changes in traffic volume and only included sites without major changes in geometry between the before and after periods. The estimated Minnesota CMFs showed similar trends to CMFs in the literature review. For left-turn crashes, the Minnesota CMFs ranged from 0.79-0.82 for converting protected-permissive and permissive-only to FYA and ranged 1.05-1.45 for converting from protected-only to FYA. The study concluded the safety performance of FYA signals in Minnesota is similar to the safety performance of FYA signals in other states.

Study Citation: Storm, R., R. O'Keefe, R. Srinivasan, B. Lan, S, Klump, R. Herring, and B. Wemple. "Flashing Yellow Arrow Signal Safety Evaluation." Report No. TBD. Minnesota Department of Transportation. Roseville, Minnesota. (November 2020).


CMFs Associated With This Study

Category: Intersection traffic control

Countermeasure: Changing left turn phasing from permissive to flashing yellow arrow (FYA)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.38961.12 StarsAllK,A,B,CAllAll
0.46753.32 StarsAllAllAllAll
0.52747.32 StarsLeft turnAllAllAll
1.023-2.31 StarRear endAllAllAll
0.19580.52 StarsOtherAllAllAll
0.44855.22 StarsOtherAllAllAll
0.40159.92 StarsAllK,AAllAll
0.53472 StarsAllK,A,BAllAll

Countermeasure: Changing left turn phasing from protected to flashing yellow arrow (FYA)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.30569.52 StarsRear endAllAllAll
0.14285.82 StarsOtherAllAllAll
1.162-16.22 StarsOtherAllAllAll
1.241-24.11 StarAllK,AAllAll
1.247-24.71 StarAllK,A,BAllAll
0.76723.32 StarsAllK,A,B,CAllAll
0.86613.42 StarsAllK,A,B,CAllAll
0.81618.42 StarsAllAllAllAll
3.06-2061 StarRear endAllAllAll
0.61338.72 StarsOtherAllAllAll
0.68331.72 StarsOtherAllAllAll
0.30569.52 StarsAllK,AAllAll
1.094-9.42 StarsAllK,A,BAllAll
0.9029.82 StarsAllK,A,B,CAllAll
0.79520.51 StarAllK,AAllAll
1.356-35.62 StarsAllK,A,BAllAll
1.445-44.52 StarsLeft turnAllAllAll
1.011-1.12 StarsAllAllAllAll
1.21-212 StarsLeft turnAllAllAll
0.44755.32 StarsRear endAllAllAll
0.27272.82 StarsOtherAllAllAll
0.9594.12 StarsOtherAllAllAll
0.50849.22 StarsAllK,AAllAll
1.3431 StarAllK,A,BAllAll
0.9346.62 StarsAllK,A,B,CAllAll
1.146-14.62 StarsAllAllAllAll
1.052-5.21 StarLeft turnAllAllAll
1.076-7.62 StarsAllAllAllAll
1.424-42.42 StarsLeft turnAllAllAll
1.115-11.51 StarRear endAllAllAll
0.37632 StarsOtherAllAllAll
1.003-0.32 StarsOtherAllAllAll

Countermeasure: Changing left turn phasing from protected-permissive to flashing yellow arrow (FYA)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.88311.71 StarAllK,AAllAll
1.082-8.22 StarsAllK,A,BAllAll
0.59340.72 StarsAllK,A,B,CAllAll
0.76223.82 StarsAllAllAllAll
0.81718.32 StarsLeft turnAllAllAll
0.86813.21 StarRear endAllAllAll
0.9792.11 StarAllK,AAllAll
1.071-7.12 StarsAllK,A,BAllAll
0.57742.32 StarsAllK,A,B,CAllAll
0.74262 StarsAllAllAllAll
0.79220.82 StarsLeft turnAllAllAll
0.9079.31 StarRear endAllAllAll
0.72227.82 StarsOtherAllAllAll
0.74325.72 StarsOtherAllAllAll