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Train Control Upgrade Program

Project Timeline 
Winter 2018
Planning: Winter 2018 - Summer 2020
Summer 2020
Detail Design: Summer 2020 - Summer 2026
Fall 2021
Construction: Fall 2021 - Fall 2027
Current Phase or Stage
Predicted Completion
Fall 2027
Project Status
SFMTA Muni Metro train icon
Improve service across the entire Muni light rail system


1. Automatic Train Control System (ATCS)

ATCS controls the automatic movement of Light Rail Vehicles (LRV) through the Muni Metro Subway. ATCS is a type of Communications-based Train Control (CBTC) system. 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. Communications-based Train Control (CBTC) system

Our current ATCS uses loop cable to permit communications between the train and the infrastructure in the subway. New CBTC technology uses WiFi or Cellular connections to precisely track and continually communicate with every LRV in service. The existing loop-cable based system cannot be used in situations where a train shares the road with cars. With the new technology, CBTC can manage train movements throughout the entire 74-mile light rail network.

In the subway, CBTC will work like the ATCS and use automatic headway management to adjust the speed and dwell time of trains in the subway. On the surface, the CBCT system will communicate adjustments to LRV operators who will remain in control of the train. While GPS is currently used to track LRVs on the surface, CBTC’s telecommunications technology is more accurate. The greater visibility CBTC lends to our control center and operators will result in more effective train management and better LRV service.

The Plan

The aging ATCS is frequently responsible for Muni Metro subway slowdowns. The Train Control Upgrade Program will replace the ATCS with a state-of-the-art CBTC system. The new CBTC system will reduce subway delays, enable lower headways, and deliver faster, more reliable service

First, the Train Control Upgrade Program will quickly deliver a CBTC on the surface to improve operations on the busy Third Street corridor. In addition to providing greater control over trains in this area, the CBTC will interface with traffic signals along the corridor to ensure the trains receive priority over other traffic. Next, the program will replace the train control system in the subway. Finally, the program will expand the CBTC program across the rest of the Muni Metro network.

Technological Upgrades

1. Service improvement features

  • Reduce bunching and gaps on the LRV network through automatic headway management
  • Reduce delays caused by LRVs waiting at traffic signals through coordination between the train control system and the traffic signals
  • Eliminate major subway delays by replacing outdated ATCS equipment with the latest generation of parts and equipment
  • Reduce delays due to portal entry because trains will not have to leave and re-enter the system as they leave and re-enter the subway
  • Prevent trains from failing in service by having trains enter the CBTC system in the yards; if trains fail entry checks, then they will stay in the yard with access to maintenance
  • Increased rail capacity due to lower possible headways on the surface
  • Improved ability to handle special event service for AT&T Park and Chase Center through coordination with traffic signals and closer train spacing

2. Safety improvement features

  • Automatic enforcement of train separations
  • Automatic enforcement of signals

Environmental Benefits

For almost 85 years Muni has continuously operated a network of vehicles, including light rail vehicles, that run on 100% greenhouse gas-free Hetch Hetchy hydroelectric power. Our light rail vehicle fleet played a key role in the City reaching its 2017 San Francisco Climate Action Strategy goals. Upgrading the Muni train control system from ATCS to CBTC will help the City meet future environmental goals by improving light rail vehicle service and growing ridership on the greenest transportation system in North America.

Additionally, the Train Control Upgrade Program is in line with the City’s voter-approved Transit-First Policy established in 1973. The policy prioritizes public transit, bicycling, and walking on SF Streets as an economically and environmentally preferable alternative to transportation by individual automobiles. By providing safe, reliable, rapid, and environmentally sustainable transit service, this project will support our city’s economic and population growth while reducing greenhouse gas emissions and resource consumption.