Twin Peaks Tunnel Automatic Train Control System (ATCS) W1 Crossover Activation

Definitions

1. Automatic Train Control System (ATCS)

ATCS controls the automatic movement of Light Rail Vehicles (LRV) through the MUNI Metro Subway. The system enforces a minimum safety separation between trains based on a safe braking distance from the last verified position of the rear of a preceding train. ATCS also permits vehicles to move through the tunnel at a faster pace than allowable when vehicles are operated under human control. This system is critical in supporting the current transit service levels, which are not achievable without this technology.

2. Crossover

 A crossover is a pair of switches that connects two parallel rail tracks, allowing a train on one track to cross over to the other.

3. Interlock

 An interlock is an arrangement of signals that prevents conflicting movements through an arrangement of tracks.

The Plan

As planned, the trackwork for the W1 crossover was installed but not signaled during the Twin Peak Track Replacement. The W1 crossover is the crossover closest to West Portal station in the Twin Peaks tunnel. Signaling the W1 will allow outbound trains to turn around at the West Portal inbound platform and head back into the tunnel. This project will also integrate the interlock at West Portal and Ulloa streets to automatically coordinate train traffic through West Portal station. Signaling the W1 crossover will improve subway system flexibility and efficiency thereby improving light rail service, safety, and reliability.