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(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.64 36 3 Stars All All Not specified Urban
0.79 21 2 Stars All All Not Specified Urban
0.61 39 2 Stars All All Not Specified Urban
0.25 75 2 Stars All All Not Specified Urban
0.52 48 2 Stars All All Not Specified Urban
0.59 41 2 Stars All All Not Specified Urban
0.66 34 2 Stars All All Not Specified Urban
0.72 28 2 Stars All All Not Specified Urban
0.45 55 2 Stars All All Not Specified Urban
0.62 38 2 Stars All All Not Specified Urban
0.71 29 2 Stars All All Not Specified Urban
0.76 24 2 Stars All All Not Specified Urban
1.34 -34 2 Stars Single vehicle All Not Specified Urban
0.83 17 2 Stars Single vehicle All Not Specified Urban
2.06 -106 2 Stars Single vehicle All Not Specified Urban
0 100 2 Stars Single vehicle All Not Specified
1.37 -37 2 Stars Head on,Rear end All Not Specified Urban
1.9 -90 2 Stars Head on,Rear end All Not Specified Urban
1.01 -1 2 Stars Head on,Rear end All Not Specified
1.34 -34 2 Stars Left turn,Right turn All Not Specified Urban
0.98 2 2 Stars Left turn,Right turn All Not Specified Urban
1.65 -65 2 Stars Left turn,Right turn All Not Specified Urban
1.48 -48 2 Stars Left turn,Right turn All Not Specified Urban
0.16 84 2 Stars Angle All Not Specified Urban
0.25 75 2 Stars Angle All Not Specified Urban
0.14 86 2 Stars Angle All Not Specified Urban
0 100 2 Stars Angle All Not Specified Urban
0.84 16 2 Stars Vehicle/pedestrian All Not Specified Urban
0.71 29 2 Stars Vehicle/pedestrian All Not Specified Urban
0.94 6 2 Stars Vehicle/pedestrian All Not Specified Urban
0 100 2 Stars Vehicle/pedestrian All Not Specified Urban
0.7 30 2 Stars Vehicle/bicycle All Not Specified Urban
0.86 14 2 Stars Vehicle/bicycle All Not Specified Urban
0.59 41 2 Stars Vehicle/bicycle All Not Specified Urban
3.21 -221 2 Stars Vehicle/bicycle All Not Specified Urban
0.74 26 2 Stars Vehicle/pedestrian All Not Specified Urban
0.46 54 2 Stars Vehicle/pedestrian All Not Specified Urban
0.91 9 2 Stars Vehicle/pedestrian All Not Specified Urban
0 100 2 Stars Vehicle/pedestrian All Not Specified Urban
0.5 50 2 Stars All All Not Specified Urban
0.65 35 2 Stars All All Not Specified Urban
0.48 52 2 Stars All All Not Specified Urban
0.14 86 2 Stars All All Not Specified Urban
0.9 10 2 Stars All All Not Specified Urban
0.8 20 2 Stars All All Not Specified Urban
0.87 13 2 Stars All All Not Specified Urban
1 0 2 Stars All All Not Specified Urban
0.99 1 2 Stars All All Not Specified Urban
0.89 11 2 Stars All All Not Specified Urban
0.82 18 2 Stars All All Not Specified Urban
0.93 7 2 Stars All All Not Specified Urban
0.97 3 2 Stars All All Not Specified Urban
0.92 8 2 Stars All All Not Specified Urban
0.96 4 2 Stars All All Not Specified Urban
0.84 16 2 Stars All All Not Specified Urban
0.75 25 2 Stars All All Not Specified Urban
1.12 -12 2 Stars All All Not Specified Urban
1.27 -27 2 Stars All All Not Specified Urban
0.85 15 2 Stars All All Not Specified Urban
0.8 20 2 Stars All All Not Specified Urban
0.84 16 2 Stars All All Not Specified Urban
0.92 8 2 Stars All All Not Specified Urban
1.11 -11 2 Stars All All Not Specified Urban
0.98 2 2 Stars All All Not Specified Urban
0.96 4 2 Stars All All Not Specified Urban
1.06 -6 2 Stars All All Not Specified Not specified
0.92 8 2 Stars All All Not Specified Urban
0.95 5 2 Stars All All Not Specified Urban
0.71 29 2 Stars All All Not Specified Urban
0.97 3 2 Stars All All Not Specified Urban
0.99 1 2 Stars All All Not Specified Urban
1.06 -6 2 Stars All All Not Specified Urban
0.88 12 2 Stars All All Not Specified Urban
0.76 24 2 Stars All All Not Specified Urban
0.82 18 2 Stars All All Not Specified Urban
1 0 2 Stars All All Not Specified Urban
0.97 3 2 Stars All All Not Specified Urban
0.97 3 2 Stars Single vehicle All Not Specified Urban
1.03 -3 2 Stars Single vehicle All Not Specified Urban
0.92 8 2 Stars Single vehicle All Not Specified Urban
0.82 18 2 Stars Head on,Rear end All Not Specified Urban
0.9 10 2 Stars Head on,Rear end All Not Specified Urban
0.79 21 2 Stars Head on,Rear end All Not Specified Urban
0.9 10 2 Stars Left turn,Right turn All Not Specified Urban
1.01 -1 2 Stars Left turn,Right turn All Not Specified Urban
0.82 18 2 Stars Left turn,Right turn All Not Specified Urban
0.72 28 2 Stars Angle All Not Specified Urban
0.75 25 2 Stars Angle All Not Specified Urban
0.68 32 2 Stars Angle All Not Specified Urban
0.68 32 2 Stars Vehicle/pedestrian All Not Specified Urban
0.67 33 2 Stars Vehicle/pedestrian All Not Specified Urban
0.69 31 2 Stars Vehicle/pedestrian All Not Specified Urban
0.81 19 2 Stars Vehicle/bicycle All Not Specified Urban
1.04 -4 2 Stars Vehicle/bicycle All Not Specified Urban
0.7 30 2 Stars Vehicle/bicycle All Not Specified Urban
0.62 38 2 Stars Vehicle/pedestrian All Not Specified Urban
0.65 35 2 Stars Vehicle/pedestrian All Not Specified Urban
0.62 38 2 Stars Vehicle/pedestrian All Not Specified Urban
0.87 13 2 Stars All All Not Specified Urban
0.85 15 2 Stars All All Not Specified Urban
0.86 14 2 Stars All All Not Specified Urban
0.77 23 3 Stars All All Not Specified Urban
0.81 19 2 Stars All All Not Specified Urban
0.74 26 2 Stars All All Not Specified Urban
0.81 19 2 Stars All All Not Specified Urban
0.97 3 2 Stars Single vehicle All Not Specified Urban
1.03 -3 2 Stars Single vehicle All Not Specified Urban
0.93 7 2 Stars Single vehicle All Not Specified Urban
0.89 11 2 Stars Head on,Rear end All Not Specified Urban
1.03 -3 2 Stars Head on,Rear end All Not Specified Urban
0.83 17 2 Stars Head on,Rear end All Urban
1.01 -1 2 Stars Left turn,Right turn All Not Specified Urban
1 0 2 Stars Left turn,Right turn All Not Specified Urban
1.01 -1 2 Stars Left turn,Right turn All Not Specified Urban
0.49 51 3 Stars Angle All Not Specified Urban
0.56 44 2 Stars Angle All Not Specified Urban
0.46 54 2 Stars Angle All Not Specified Urban
0.76 24 3 Stars Vehicle/pedestrian All Not Specified Urban
0.76 24 2 Stars Vehicle/pedestrian All Not Specified Urban
0.77 23 2 Stars Vehicle/pedestrian All Not Specified Urban
0.8 20 3 Stars Vehicle/bicycle All Not Specified Urban
1.03 -3 2 Stars Vehicle/bicycle All Urban
0.7 30 2 Stars Vehicle/bicycle All Not Specified Urban
0.7 30 3 Stars Vehicle/pedestrian All Not Specified Urban
0.68 32 2 Stars Vehicle/pedestrian All Not Specified Urban
0.72 28 2 Stars Vehicle/pedestrian All Not Specified Urban
0.79 21 3 Stars All All Not Specified Urban
0.79 21 2 Stars All All All Urban
0.77 23 2 Stars All All Not Specified Urban