Our traffic signal inventory includes flashing 20 MPH school zone signs, intersection warning beacons, and stop-and-go (red/yellow/green) signals. The purpose of these devices is to provide for the safety of private vehicles, transit vehicles, bicycles, and pedestrians. The Department designs its traffic signals to provide the following:
* Allocation of the right-of-way in the safest way possible among all modes of transportation
* Maximum comfort and convenience for people crossing intersections on foot
* Reduction of red light running and its consequences
* Efficient movement of vehicles along arterial corridors for vehicles that are traveling at
below the speed limit
The Department owns and operates a total of 191 traffic signals, including:
* 134 stop-and-go signals
* 23 intersection warning beacons
* 34 school zone flashers
An additional 33 traffic signals are within the City boundary, but are operated by the District of Conservation and Recreation.
Some specific features of our traffic signals include:
* Light-Emitting Diode (LED) Lamps: Not only LED lamps brighter than the old incandescent lamps, they also last much longer and consume far less energy.
* Countdown Pedestrian Signals: In addition to the traditional WALK and DON'T WALK symbols, countdown signals display the number of seconds remaining until the end of the pedestrian phase. These signals help make it easier for the pedestrian to decide whether to start crossing.
* Leading Pedestrian Intervals (LPI): This is simply a head start for pedestrians at intersections where cars and pedestrians are allowed to cross an intersection at the same time. At intersections with LPI, the WALK sign is turned on 3-5 seconds before the green light, so that the first vehicle intending to turn right or left is forced to yield to the group of pedestrians that has already started to cross.
* Audible Pedestrian Signals: Many intersections are equipped with units that produce and audible tone (a chirp or a tap) when the WALK sign is on. The device is intended to assist the visually impaired.
Please contact the Traffic Engineering office at (617) 349-4715 with any questions about the City of Cambridge traffic signal system.