Study Details

Study Title: Safety Effects of Intersection Signalization: a Before-After Study

Authors: Jensen

Publication Date:JAN, 2010

Abstract: This paper presents a before-after crash and injury study of intersection signalization in an urban area. Conversion from yield to signal control at 54 intersections in central Copenhagen, Denmark, is analyzed. Police recorded crashes, which occurred at converted intersections as well as crashes up to 500 meters away on roadways leading up to converted intersections, are included in the study. The method used accounts for general crash and injury trends, changes in traffic volumes, and also regression-to-the-mean effects in the before period. The best estimates for mean safety effects of intersection signalization are decreases in crashes and injuries of respectively 21 and 17 percent at 3-armed intersections, and 39 and 33 percent at 4-armed intersections. These findings are in line with previous studies. The safety benefits at converted intersections are primarily due to significant reductions in right-angle crashes. Safety is also improved on roadways up to 100 meters away from the center of the converted 3-armed intersections, and up to 200 meters away from converted 4-armed intersections. About 60 percent of the total safety improvement occurred on the roadways and only about 40 percent occurred at the converted intersections. In total, for converted intersections and roadways up to 200 meters away, the best estimates for mean safety effects of intersection signalization are decreases in crashes and injuries of respectively 19 and 21 percent near and at the 3-armed intersections, and 26 and 33 percent near and at the 4-armed intersections.

Study Citation: Jensen, S. U. "Safety Effects of Intersection Signalization: a Before-After Study." TRB 89th Annual Meeting Compendium of Papers CD-ROM. Washington, D.C. 2010.


CMFs Associated With This Study

Category: Intersection traffic control

Countermeasure: Convert from yield signal control to signalized control

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.72282 StarsAngleAllNot SpecifiedUrban
0.75252 StarsAngleAllNot SpecifiedUrban
0.68322 StarsAngleAllNot SpecifiedUrban
0.68322 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.67332 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.69312 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.81192 StarsVehicle/bicycleAllNot SpecifiedUrban
1.04-42 StarsVehicle/bicycleAllNot SpecifiedUrban
0.7302 StarsVehicle/bicycleAllNot SpecifiedUrban
0.62382 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.65352 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.62382 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.87132 StarsAllAllNot SpecifiedUrban
0.85152 StarsAllAllNot SpecifiedUrban
0.86142 StarsAllAllNot SpecifiedUrban
0.77233 StarsAllAllNot SpecifiedUrban
0.81192 StarsAllAllNot SpecifiedUrban
0.74262 StarsAllAllNot SpecifiedUrban
0.81192 StarsAllAllNot SpecifiedUrban
0.9732 StarsSingle vehicleAllNot SpecifiedUrban
1.03-32 StarsSingle vehicleAllNot SpecifiedUrban
0.9372 StarsSingle vehicleAllNot SpecifiedUrban
0.89112 StarsHead on,Rear endAllNot SpecifiedUrban
1.03-32 StarsHead on,Rear endAllNot SpecifiedUrban
0.83172 StarsHead on,Rear endAllUrban
1.01-12 StarsLeft turn,Right turnAllNot SpecifiedUrban
102 StarsLeft turn,Right turnAllNot SpecifiedUrban
1.01-12 StarsLeft turn,Right turnAllNot SpecifiedUrban
0.49513 StarsAngleAllNot SpecifiedUrban
0.56442 StarsAngleAllNot SpecifiedUrban
0.46542 StarsAngleAllNot SpecifiedUrban
0.76243 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.76242 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.77232 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.8203 StarsVehicle/bicycleAllNot SpecifiedUrban
1.03-32 StarsVehicle/bicycleAllUrban
0.7302 StarsVehicle/bicycleAllNot SpecifiedUrban
0.7303 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.68322 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.72282 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.79213 StarsAllAllNot SpecifiedUrban
0.79212 StarsAllAllAllUrban
0.77232 StarsAllAllNot SpecifiedUrban
0.9102 StarsAllAllNot SpecifiedUrban
0.8202 StarsAllAllNot SpecifiedUrban
0.87132 StarsAllAllNot SpecifiedUrban
102 StarsAllAllNot SpecifiedUrban
0.9912 StarsAllAllNot SpecifiedUrban
0.89112 StarsAllAllNot SpecifiedUrban
0.82182 StarsAllAllNot SpecifiedUrban
0.9372 StarsAllAllNot SpecifiedUrban
0.9732 StarsAllAllNot SpecifiedUrban
0.9282 StarsAllAllNot SpecifiedUrban
0.9642 StarsAllAllNot SpecifiedUrban
0.84162 StarsAllAllNot SpecifiedUrban
0.75252 StarsAllAllNot SpecifiedUrban
1.12-122 StarsAllAllNot SpecifiedUrban
1.27-272 StarsAllAllNot SpecifiedUrban
0.85152 StarsAllAllNot SpecifiedUrban
0.8202 StarsAllAllNot SpecifiedUrban
0.84162 StarsAllAllNot SpecifiedUrban
0.9282 StarsAllAllNot SpecifiedUrban
1.11-112 StarsAllAllNot SpecifiedUrban
0.9822 StarsAllAllNot SpecifiedUrban
0.9642 StarsAllAllNot SpecifiedUrban
1.06-62 StarsAllAllNot SpecifiedNot specified
0.9282 StarsAllAllNot SpecifiedUrban
0.9552 StarsAllAllNot SpecifiedUrban
0.71292 StarsAllAllNot SpecifiedUrban
0.9732 StarsAllAllNot SpecifiedUrban
0.9912 StarsAllAllNot SpecifiedUrban
1.06-62 StarsAllAllNot SpecifiedUrban
0.88122 StarsAllAllNot SpecifiedUrban
0.76242 StarsAllAllNot SpecifiedUrban
0.82182 StarsAllAllNot SpecifiedUrban
102 StarsAllAllNot SpecifiedUrban
0.9732 StarsAllAllNot SpecifiedUrban
0.9732 StarsSingle vehicleAllNot SpecifiedUrban
1.03-32 StarsSingle vehicleAllNot SpecifiedUrban
0.9282 StarsSingle vehicleAllNot SpecifiedUrban
0.82182 StarsHead on,Rear endAllNot SpecifiedUrban
0.9102 StarsHead on,Rear endAllNot SpecifiedUrban
0.79212 StarsHead on,Rear endAllNot SpecifiedUrban
0.9102 StarsLeft turn,Right turnAllNot SpecifiedUrban
1.01-12 StarsLeft turn,Right turnAllNot SpecifiedUrban
0.82182 StarsLeft turn,Right turnAllNot SpecifiedUrban
0.64363 StarsAllAllNot specifiedUrban
0.79212 StarsAllAllNot SpecifiedUrban
0.61392 StarsAllAllNot SpecifiedUrban
0.25752 StarsAllAllNot SpecifiedUrban
0.52482 StarsAllAllNot SpecifiedUrban
0.59412 StarsAllAllNot SpecifiedUrban
0.66342 StarsAllAllNot SpecifiedUrban
0.72282 StarsAllAllNot SpecifiedUrban
0.45552 StarsAllAllNot SpecifiedUrban
0.62382 StarsAllAllNot SpecifiedUrban
0.71292 StarsAllAllNot SpecifiedUrban
0.76242 StarsAllAllNot SpecifiedUrban
1.34-342 StarsSingle vehicleAllNot SpecifiedUrban
0.83172 StarsSingle vehicleAllNot SpecifiedUrban
2.06-1062 StarsSingle vehicleAllNot SpecifiedUrban
01002 StarsSingle vehicleAllNot Specified
1.37-372 StarsHead on,Rear endAllNot SpecifiedUrban
1.9-902 StarsHead on,Rear endAllNot SpecifiedUrban
1.01-12 StarsHead on,Rear endAllNot Specified
1.34-342 StarsLeft turn,Right turnAllNot SpecifiedUrban
0.9822 StarsLeft turn,Right turnAllNot SpecifiedUrban
1.65-652 StarsLeft turn,Right turnAllNot SpecifiedUrban
1.48-482 StarsLeft turn,Right turnAllNot SpecifiedUrban
0.16842 StarsAngleAllNot SpecifiedUrban
0.25752 StarsAngleAllNot SpecifiedUrban
0.14862 StarsAngleAllNot SpecifiedUrban
01002 StarsAngleAllNot SpecifiedUrban
0.84162 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.71292 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.9462 StarsVehicle/pedestrianAllNot SpecifiedUrban
01002 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.7302 StarsVehicle/bicycleAllNot SpecifiedUrban
0.86142 StarsVehicle/bicycleAllNot SpecifiedUrban
0.59412 StarsVehicle/bicycleAllNot SpecifiedUrban
3.21-2212 StarsVehicle/bicycleAllNot SpecifiedUrban
0.74262 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.46542 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.9192 StarsVehicle/pedestrianAllNot SpecifiedUrban
01002 StarsVehicle/pedestrianAllNot SpecifiedUrban
0.5502 StarsAllAllNot SpecifiedUrban
0.65352 StarsAllAllNot SpecifiedUrban
0.48522 StarsAllAllNot SpecifiedUrban
0.14862 StarsAllAllNot SpecifiedUrban