South Station Expansion – Tower 1 Interlocking

Rail/Transit, Rail
Bid Build
Boston, MA
Massachusetts Bay Transportation Authority

Middlesex is rebuilding and upgrading Tower 1 Interlocking and Cove Interlocking. Scope includes sitework, trackwork, structural, power, lighting, signals, and communication work.

Tower 1 interlocking area: (1) Replacement of trackwork. (2) Foundation & platform for a new 60ft x 10ft central instrument house. (3) Upgrading of the existing relay based signal system with a microprocessor based signal system. (4) Replacement of existing back-up power generator from 150kVA to 300kVA. (5) New lighting & replacement of floodlights. (6) Additions to the communications & security systems. (7) Replacement of trackwork & associated signal infrastructure within the Cove interlocking area.

By the Numbers

$2M
Civil Work

$13M
Track Work

$34M (35% of Project Value)
Electrical Work

$98.6M
Project Value

Scope of Work
  • End of the line layover facility
  • System installation
  • Positive train control
  • Program-wide signals and communications systems
  • Electrical Signal/Systems/PTC
  • Track work
  • Civil Work / Drainage / Culverts
  • Retaining Walls
Unique Challenges
  • 5 year project – most completed during 105 weekends of closure from 10PM Friday – 6AM Monday
  • No track work was allowed from December 1st to March 15th