Maryland designs for calmer traffic on urban highway

By Michael Brenneis
Arterials bounded by urban or suburban development cease to function exclusively as throughways, and are good candidates for reconfiguration to support the land uses that surround them. As more bicyclists and pedestrians use a corridor, conflict with motor vehicles and resulting crashes can increase. These corridors can be dangerous places. When residents demand protection from traffic dangers to create more walkable, livable neighborhoods, state DOTs are increasingly called on to shift their focus from exclusively measuring the level of service provided to drivers, to designing for the safety and accessibility of pedestrians and cyclists.
The Maryland Department of Transportation State Highway Administration is following this approach in the densely settled areas north of Washington D.C.—along the highway 97 (Georgia Avenue) corridor—by reducing speed limits, narrowing travel lanes from 12 feet to 10 feet, and adding continental-style crosswalks and pedestrian-activated crossing signals.
According to a new article in the ITE Journal, engineers who are newer to the field seem drawn to this approach. Although engineers view speed distribution as a key factor when setting speed limits—and rounding speed limits to the nearest 5 mph of the 85th percentile is still common practice—traffic engineers with ten or fewer years in the field see context, bicyclist and pedestrian activity, and policy as important factors when setting speed limits.
The Maryland example stands out as good policy coming to fruition. Several other state DOTs—including those in Massachusetts, California, and Washington—have endorsed the NACTO Urban Street Design Guide and are having varying degrees of success incorporating the suggested designs, which include traffic calming measures and pedestrian countermeasures similar to those being installed in Maryland.
Michael Brenneis is an Associate Researcher at SSTI.