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Train Control Upgrade Project

Project Timeline 
Winter 2018
Spring 2023
Preliminary Engineering and Detail Design
Summer 2024
Current Phase or Stage
Predicted Completion
Project Status
Muni Metro train
Improve service across the entire Muni light rail system

The Plan

The Train Control Upgrade Project (TCUP) is a comprehensive capital program designed to improve Muni Metro light rail service by providing operations staff with the tools necessary to deliver reliable, speedy, high-frequency transit to, from, and within downtown San Francisco. The TCUP invests in the core rail system by replacing the over 20-year old automatic train control system (ATCS) in the Market Street Subway while expanding modern train control to the surface. In the first five years, the project will pilot a new communications-based train control (CBTC) system on the street-level Embarcadero and Third Street corridors, which serves high-traffic destinations such as Oracle Park, Chase Center, Mission Bay and UCSF, and will modernize the existing automatic train control system (ATCS) in the Market Street Subway by overlaying the same CBTC system so that Muni Metro train control is provided by a single CBTC system. Over the full 10-year span of the project, CBTC will subsequently expand to the surface branches of the J, K, L, M, N, and T lines.


  1. Automatic Train Control System (ATCS)

ATCS is a type of train control system that is currently in use in the Market Street Subway. ATCS controls the automatic movement of Light Rail Vehicles (LRV) with electronic loop cables that permit communication between the trains and signal infrastructure in the subway. The system enforces a minimum safety separation between trains based on safe braking distances from the last known position of preceding trains. ATCS also permits trains to move through the tunnel at a faster pace than allowable when vehicles are operated entirely under human control. Current Muni Metro transit service is not possible without this technology.

  1. Communications-based Train Control (CBTC) 

Unlike the existing ATCS, newer 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 outside the subway. 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 existing ATCS and use automatic headway management to adjust the speed and dwell time of trains. On the surface, the CBTC 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 and more directly accessible to the control center staff. The greater visibility CBTC lends to our control center and operators will result in more effective train management and better LRV service for the entire Muni Metro system.

Project Objectives and Benefits

  • Increase the capacity of the Muni Metro system
  • Maintain the high standards of safety currently provided in the subway and extend modern safety protections to surface operations
  • Enable shorter, more consistent travel times and headways
  • Provide a train control system that supports Muni Metro service at all times
  • Support configurable and flexible service changes and contingency operations
  • Continually update the new system to include the latest service-proven components and software

Technological Upgrades

  1. Service improvement features
  • Reduce train bunching and gaps on the network through automatic headway management
  • Reduce surface delays through coordination between the train control system and traffic signals
  • Eliminate major subway delays and improve reliability by replacing outdated ATCS equipment
  • Reduce delays due to portal entry by providing a single CBTC system for all of Muni Metro
  • Increased rail capacity and lower headways due to CBTC management on the surface

2. Safety improvement features

  • Automatic enforcement of train separation
  • 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.