Protected intersections fully comply with existing design standards.
“The Manual on Uniform Traffic Control Devices (MUTCD) is about markings and signs,” says Nick Falbo, senior planner for Alta Planning + Design. “Protected intersections are about geometric design, using geometry to manage speed and mitigate conflicts. The design looks different than what we’re used to, but it complies with all requirements for markings and signs.”
Although intersection elements comply with geometric design standards like the American Association of State Highway and Transportation Officials’ “Green Book,” there’s no national formal design guide.
“States and cities are leading the way,” Falbo says. For example, the Massachusetts DOT Separated Bike Lane Planning & Design Guide has a 40-page chapter illustrating the design.
There is a parting of the ways when it comes to signaling, however.
MUTCD doesn’t include provisions for signal faces with bicycle symbols. It calls for standard circular signals to control bicycles and doesn’t prohibit using arrows for bikeways. In 2013 FHWA issued an MUTCD Interim Approval for using bicycle signal faces under limited conditions that prohibits simultaneous green or leading bicycle interval phasing.
The rules’ implications depend on how the intersection is configured. If it uses standard traffic control signals there are no special requirements. But certain signaling restrictions may not be compatible with specific components of the protected intersection design.
“A signal engineer should be involved,” Falbo says.
Under the Interim Approval, jurisdictions seeking to use bicycle signal faces must go through the MUTCD experimentation process. Those that have report better bicyclist compliance with traffic control and lower bicycle crash rates.
States also have latitude in adopting the national standard.
Some use MUTCD as the basis for developing their own traffic control device manuals. For example, California’s MUTCD allows bicycle signal faces and the City of Davis has been using them since the 1990s.
The city’s Cannery intersection doesn’t yet feature dedicated bicycle signaling. “However, the signal is equipped with the hardware and it could be implemented when the bike volume justifies it,” says Public Works Senior Civil Engineer Roxanne Namazi.
Protected intersections include accessibility features such as curb ramps, tactile warnings in pedestrian safety islands, and pedestrian signal heads.
“There’s some concern about the pedestrian crossing of the bikeway for people with vision disabilities because bicycles operate fairly silently and lack audible clues,” says Falbo. “This isn’t an issue if pedestrians can actuate the signal from the sidewalk without having to enter the pedestrian safety island.”