About the research
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 displays effectiveness was not due to its novelty.
Vendor: Speed Measurement Labs