Impact of red light cameras on car crashes. To combat red-light-running crashes many states have installed red light cameras at dangerous intersections to photograph the license plates of vehicles that run the red light. How effective are photo-red enforcement programs in reducing red-light-running crash incidents at intersections? The Virginia Department of Transportation (VDOT) conducted a comprehensive study of its photo-red enforcement program. In one portion of the study, the VDOT provided crash data both before and after installation of red light cameras at several intersections. The data (measured as the number of crashes caused by red light running per intersection per year) for 13 intersections in Fairfax County, Virginia, are given in the table. Analyze the data for the VDOT. What do you conclude?
Intersection | Before Camera | After Camera |
1 | 3.60 | 1.36 |
2 | 0.27 | 0 |
3 | 0.29 | 0 |
4 | 4.55 | 1.79 |
5 | 2.60 | 2.04 |
6 | 2.29 | 3.14 |
7 | 2.40 | 2.72 |
8 | 0.73 | 0.24 |
9 | 3.15 | 1.57 |
10 | 3.21 | 0.43 |
11 | 0.88 | 0.28 |
12 | 1.35 | 1.09 |
13 | 7.35 | 4.92 |
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