30+ radar speed signs in Bellevue, WA

Perhaps the most comprehensive field study on the effectiveness of radar speed signs was just conducted by the city of Bellevue, Washington. Results were so overwhelmingly positive that the city rewrote their own rulebook on when and how to use these traffic-calming displays.

Prior to the study, Bellevue city officials viewed radar speedcheck signs as a secondary fallback option for applications where speedbumps, traffic circles or other physical traffic calming measures just could not be installed. But that has changed. Due in most part to the results of their own study, Bellevue has now installed more than thirty permanently mounted radar speed displays around school zones, on neighborhood streets and other locations where speeding traffic is a concern – and in many cases, in locations where speedbumps might once have been employed.

Old habits are hard to break. It doesn’t take a scientist to conclude that a big obstruction in the street (speedbump) will tend to slow drivers, and so installing them has often been the knee-jerk response that many cities exhibit when speeding traffic becomes an issue. 

What simple observation may not show, however, are some of the signficiant drawbacks to speedbumps. Drivers, for instance, oftentimes increase their speed from bump to bump. Speedbumps slow fire trucks, ambulances and other emergency vehicles and may increase traffic noise and present a hazard to bicyclists and handicap pedestrians.  The installation of speedbumps often result in simply shifting traffic from a main through route to quiet neighborhood side streets.

According to the Bellevue report, radar speed signs have a similar effect in slowing traffic, without the drawbacks associated with traffic calming road obstructions. Speedcheck signs have no effect on emergency vehicles or bicycles. They don’t cause increased traffic noise and they don’t cause damage to your automobile.

Perhaps most surprising to those following the Bellevue study is that the radar speedcheck signs continued to be effective over a long period of time. In some cases average traffic speeds continued to decrease years after the radar displays were first installed.

The Bellevue report not only provided evidence of the effectivness of radar speedcheck signs but also provided experienced recommendations on choosing and installing the displays. A review of these findings coming up in our next blog post.