CASE STUDY NATIONAL

Bellevue, Washington installed 31 stationary radar signs as of January 2009. They had a budget of $50,000 to devote to traffic safety technologies and decided that the use of stationary radar signs would be a good opportunity for investment. The City relied on police enforcement to address speeding issues and concerns on streets that did not qualify for other traffic calming measures. These streets were primarily arterial with a posted speed of 30 mph or saw traffic volumes of greater than 3,000 vehicles per day. Speed radars were installed in these areas and began to expand to other streets that did not meet either of these criteria and could accommodate for other traffic calming techniques.

Three studies were done to determine the effectiveness over time. The first study was done for all 31 existing radar signs after having been installed from 1 – 3 years. Several locations showed little speed reductions during the first installation, and one even showed an increase in speeds. The second study focused on 22 located where signs had been in place for two or more years. These studies showed an increase in the effectiveness of the signs. It should be noted that some of the speed radars were replaced or repaired if they were not working well. The third study was done for ten locations where the radar signs had been there for six or more years. During this study, the radars showed an increase in effectiveness and have not lost effectiveness over time.

This study shows that motorists are starting to correct their driving habits and speeds when necessary. The public perception also remains positive with growing requests for new installations of these radar signs. The City has put funding aside in anticipation for repairs and replacements or upgrades for each sign every seven years.