Two years from now, Muni buses will have traffic signal priority at 600 intersections throughout the city, SFMTA Transit Effectiveness Project (TEP) Manager Julie Kirschbaum told the agency’s board of directors today.

The signals will speed buses along all of Muni’s priority “rapid” route network, which encompasses half of San Francisco’s roughly 1,200 signalized intersections, she said.

Transit-priority traffic signals would substantially speed up Muni trips by “allow[ing] us to extend greens and reduce the amount of time buses spend sitting at signals,” said Kirschbaum in an update on the TEP [PDF] presented to the board.

The signals, which would use GPS to hold green lights for buses and trains as they approach an intersection, will be installed using $20.3 million from the Prop B street improvements bond measure approved by voters last November. “It really is a substantial investment,” said Kirschbaum.

Although staff is currently performing environmental review and public outreach on physical street improvements recommended in the TEP, other improvements are moving ahead, like signal priority and system-wide all-door boarding, which is expected to begin on July 1.

When the rest of the TEP is implemented by 2017, said Kirschbaum, it will add other street improvements to facilitate signal priority, including colored bus-only lanes, right-turn lanes for other vehicles, and bus stops moved to the far side of intersections.

Some intersections already have transit-priority signals, but staff said they use outdated technology, and many have been poorly maintained. The new signals will also replace stop signs on some routes.