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South Station Signal and Track Improvements Project

The Tower One interlocking signals and tracks leading to from South Station
An interlocking is a group of signals that controls train movements across junctions, where tracks meet. They are designed to make sure trains only proceed along a route if it is safe.

The South Station Signal and Track Improvements Project will focus on the Tower One interlocking and Cove interlocking, which control all rail traffic in and out of South Station, the second largest multimodal transportation facility in New England.

We’re upgrading the Tower One track and signal system and the Cove track system to improve the reliability of service at South Station. This work will also support future growth of the MBTA and Amtrak. We are using Widett Circle to stage materials and equipment for the critically important Tower One project, which is under construction. 

Design contract awarded: January 2021
Construction contract awarded: May 2023
Projected completion: Early 2028
Budget: $169 million
Status: Construction started in May 2023 

Building a Better T

As part of our $9.6 billion, 5-year capital investment plan, we're renovating stations, modernizing fare collection systems, upgrading services for our buses, subways, and ferries, and improving the accessibility of the entire system.

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Why We’re Doing this Work

Tower One Interlocking

The existing Tower One signal system is outdated and sometimes causes service interruptions—due to the number of trains traveling through the interlocking, even a 5-minute shutdown can create residual delays. At Tower One interlocking, we will:

  • Replace the existing master signal system with a new signal instrumentation house that will manage all rail traffic in the South Station interlocking 
  • Replace all of the major interlocking track switches, interconnecting tracks, power systems, lighting, and security features 
  • Replace the existing switch heater system for the train tracks with a state-of-the-art, wirelessly controlled system 
  • Address settling that has occurred at switch points 
  • Replace generators to support power loads required by today’s equipment 

Cove Interlocking

The trackwork at Cove interlocking is nearing the end of its service life. To ensure reliable train routing continues, we will:

  • Replace the top and bottom layers of track bed
  • Replace all of the major interlocking track switches, interconnecting tracks, power systems, lighting, and security features.
Map showing the limits of Tower 1 Interlocking and Cove Interlocking construction along the train tracks between South Station and Back Bay station. Tower 1 Interlocking starts at South Station and crosses over I-90 to Cove Interlocking and Cove Interlocking crosses under I-93 and runs along I-90.
Map showing the limits of Tower 1 Interlocking and Cove Interlocking construction along the train tracks between South Station and Back Bay station.

Contact Us

For questions and comments related to the South Station Tower One Interlocking Project, please contact Tower1SSX@mbta.com.

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Building a Better T

As part of our $9.6 billion, 5-year capital investment plan, we're renovating stations, modernizing fare collection systems, upgrading services for our buses, subways, and ferries, and improving the accessibility of the entire system.

Learn more

Related Projects

View all projects