In addition to requiring tollway authorities to use purple for pavement markings and electronic signs, the first major update to the Manual on Uniform Traffic Control Devices (MUTCD) since 2003 provides detailed direction for round-about signs, signals, and pavement markings and enhances walkability.

The Federal Highway Administration, which has administered the manual since 1971, received, considered, and incorporated 15,000 comments regarding proposed changes. “That's a significant amount of effort to develop a new federal standard, and they did it within six months,” says Dave McKee, director of technical assistance for the American Traffic Safety Services Association. “The guidelines are so detailed they address roundabouts that may include two or three arterial systems.”

To give pedestrians more time to cross a street, the formula for calculating walk time at intersections was changed from 4 feet/second to 3.5 feet/second. The deadline for updating countdown signals is Dec. 22, 2013.

Among other provisions, the agency is allowing 8-inch-diameter signals to be installed in low-speed urban areas by lowering the threshold from 40 mph to 30 mph.

States have two years to adopt the new manual as their statutory traffic signal standards. For more information and links to the manual itself, visit