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Impact of red light cameras on car crashes. To combat
Chapter 8, Problem 40E(choose chapter or problem)
Problem 40E
Impact of red light cameras on car crashes. To combat red-light-running crashes—the phenomenon of a motorist entering an intersection after the traffic signal turns red and causing a crash—many states are adopting photored enforcement programs. In these programs, red light cameras installed at dangerous intersections 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 newly adopted photored enforcement program and published the results in aJune 2007 report. 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 and saved in the REDLIGHT file.
Intersection |
Before Camera |
After Camera
|
|
1 2 3 4 5 6 7 8 9 10 11 12 13 |
3.60 0.27 0.29 4.55 2.60 2.29 2.40 0.73 3.15 3.21 0.88 1.35 7.35 |
1.36 0 0 1.79 2.04 3.14 2.72 0.24 1.57 0.43 0.28 1.09 4.92 |
Analyze the data for the VDOT. What do you conclude? Based on Virginia Transportation Research Council, “Research report: The impact of red light cameras (photo-red enforcement) on crashes in Virginia.” June 2007.
Questions & Answers
QUESTION:
Problem 40E
Impact of red light cameras on car crashes. To combat red-light-running crashes—the phenomenon of a motorist entering an intersection after the traffic signal turns red and causing a crash—many states are adopting photored enforcement programs. In these programs, red light cameras installed at dangerous intersections 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 newly adopted photored enforcement program and published the results in aJune 2007 report. 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 and saved in the REDLIGHT file.
Intersection |
Before Camera |
After Camera
|
|
1 2 3 4 5 6 7 8 9 10 11 12 13 |
3.60 0.27 0.29 4.55 2.60 2.29 2.40 0.73 3.15 3.21 0.88 1.35 7.35 |
1.36 0 0 1.79 2.04 3.14 2.72 0.24 1.57 0.43 0.28 1.09 4.92 |
Analyze the data for the VDOT. What do you conclude? Based on Virginia Transportation Research Council, “Research report: The impact of red light cameras (photo-red enforcement) on crashes in Virginia.” June 2007.
ANSWER:Step 1 of 3
The sample mean is the simple average of any sample to be analyzed. The sample is derived from the population under study that needs to be studied from the basic level of analysis. Considering average or mean is the simple measure of central tendency, the average of all sample observations is taken as the sample mean.