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South Station Tower One Interlocking 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. They are designed to make it impossible for a signal to send a train along a route unless it is safe.

The Tower One interlocking plays an essential role in the operation of South Station: it controls all rail traffic in and out of the second largest multimodal transportation facility in New England.

We’re upgrading the Tower One signal system to improve the reliability and resiliency of service at South Station. This work will also support future growth of the MBTA and Amtrak.

Design contract awarded: February 2021
Projected completion: Summer 2027
Budget: Estimate in progress
Status: Final design; construction expected to start in spring 2022

Building a Better T

As part of our $8 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

Why We’re Doing this Work

The existing Tower One signal system is outdated and sometimes causes service interruptions—due to the number of trains traveling through the interlocking, even a 5-minute shutdown can create residual delays.

The Tower One project will:

  • Replace the existing signal system
  • Upgrade switches, tracks, and power systems
  • Address settling that has occurred at switch points
  • Replace generators to support power loads required by today’s equipment

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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 $8 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