In the UK right now, there's a campaign known as "20 is plenty." In other words, 20 miles per hour is deemed a desirable speed on roads other than highways and arterials. In Phoenix, however, we cap speed at 25 MPH on local streets and allow speeds up to 35 MPH on collectors. The speed limits on collector streets in particular should be lowered.

The trends in collector street usage support lower speed limits. In recent years, Phoenix has added countless miles of bike lanes on collector streets such as Maryland, Sweetwater, Cholla, 15th Avenue, and 36th Street. These bike lanes help create continuous corridors of several miles where bicyclists can travel without dealing with multiple lanes of automobile traffic. In addition, most of these streets are lined with residences rather than businesses. Several of them have schools located along them. The large number of children either walking or riding bikes on these collector streets is another reason to reduce speed limits.

To date, the City's main approach has been a collector street traffic calming program, funded by the 2006 bonds. It's a good effort, and the roundabouts and other traffic-calming mechanisms added have made collector streets more civilized. Nevertheless, there are still some drivers who accelerate to nearly 40 MPH between the traffic calming structures. Reducing the speed limits on collectors to 25 MPH would have a practical effect of making the actual top speed closer to 30 MPH since many drivers will settle at a perceived "reasonable and prudent" five miles over the posted limit in the absence of strict enforcement.

Although 10 MPH might seem a small difference from inside a car, it makes a huge difference to a pedestrian or bicyclist hit by a car. One commonly quoted set of statistics (link below) estimates a 70% death rate for persons struck by cars traveling at 40 MPH and an 80% survival rate for persons struck by cars traveling at 30 MPH. Let's improve the odds on our collector streets.