Operations and Signalling
The Green Line is signalled with advisory wayside signals except on surface portions in street medians or in-street running. Wayside signal territory stretches from Lechmere to the surface portals at Kenmore, and along the D-Riverside branch. There are no automatic protection devices, as the vehicles are equipped with track brakes, giving the operator the ability to stop quickly. However, collisions do occur. Interlockings are controlled through a wayside Automatic Vehicle Identification (AVI) system that relies on the operator properly entering the destination manually on a roto-wheel in the train cab.
The Green Line is monitored from the 45 High Street rapid transit control room. Responsibility for controlling service is shared by the control room and field personnel located along the right of way. Track circuit and signal indications are not transmitted to the operational personnel sites. In lieu of track circuit indications, the AVI system is displayed in the control room to provide a periodic update to train position wherever AVI detectors exist. The AVI system user interface was solely text based until the current control room was opened, in which a new schematic display based on AVI data was instituted. Track circuit indications are available digitally in three signal houses but not transmitted to central control—at Park Street interlocking, at the new North Station interlocking, and at the new Kenmore interlocking.
Plans to reinstitute a crossover for through movements from the terminating (inner) northbound platform at Park Street towards Government Center are expected to increase capacity on the Green Line.
Read more about this topic: Green Line (MBTA)
Famous quotes containing the word operations:
“There is a patent office at the seat of government of the universe, whose managers are as much interested in the dispersion of seeds as anybody at Washington can be, and their operations are infinitely more extensive and regular.”
—Henry David Thoreau (1817–1862)