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Radar Speed Display

Status: Complete

Description: The MwSWZDI has evaluated radar actuated speed displays in several contexts. One of the most significant criticisms of previous evaluations has been that data were only collected for a relatively short time period (e.g., one week or less). Popular thought is that the displays are effective for only a few days, after which the novelty effect dissipates and drivers begin to ignore the device. This evaluation was conducted on a two-lane rural commuter route just west of Lawrence, Kansas. Data were collected for approximately one hour each work day for approximately 8 weeks. The speed display was present for five weeks, with one and a half weeks of before data and one and a half weeks of after data. The data showed statistically significant reductions in mean speed, 85th percentile speed, and percent speeding. Mean and 85th percentile speed reductions were both about 5 mph. Percent speeding dropped from about 80% (baseline) to about 40% when the display was present. The percent of drivers traveling at least 5 mph over the speed limit dropped from about 30% to less than 5%. The reductions were consistent for the entire deployment, demonstrating that the speed display’s effectiveness was not due to its novelty.

Report: MwSWZDI-2003-Meyer-Speed_Display.pdf 592 kb (published 2003)

State conducting research: Kansas


  • Speed Measurement Labs


  • Meyer, Eric (University of Kansas)
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