Connecticut River Mainline (CRML) Bridge 47.90 in Northfield, Massachusetts, is a single‑track, single‑span masonry stone arch structure originally built in 1848 for the Boston & Maine Railroad. For more than a century, the bridge carried freight service with minimal passenger operations until MassDOT Rail and Transit Division acquired the line and began a major effort to restore and modernize the corridor. To prepare the 175‑year‑old structure for expanded freight and passenger rail service, STV served as engineer of record and delivered a full rehabilitation program that strengthens the bridge while preserving its historic character.
What challenges did STV address?
The aging stone arch bridge required significant upgrades to support modern rail loading, drainage and safety requirements. Working within a historic structure with limited shutdown opportunities, STV needed to evaluate short‑ and long‑term alternatives, address aging timber deck components and help MassDOT determine appropriate capital planning. Restoring the bridge quickly and safely while maintaining the structural integrity of the original masonry arch posed a complex engineering challenge.
What solutions did STV deliver?
STV provided preliminary and final design, bridge inspection and full construction phase services, including resident engineering. The team used accelerated bridge construction (ABC) methods to replace the existing timber deck with a ballasted precast concrete deck panel system, along with new drainage elements and a safety walkway. All deck replacement work was completed during a 72‑hour weekend shutdown, including setting precast panels, performing closure pours, waterproofing and restoring track. The project received the 2024 Bronze Award from ACEC Massachusetts.
How does this project benefit the community?
The upgraded bridge improves reliability and safety for both freight and future passenger rail service, supporting MassDOT’s long‑term vision for expanded rail in Western Massachusetts. The modernized structure preserves a historic asset while enabling increased service capacity and operational resilience.
Key stats and accolades
- 72 hours of accelerated bridge construction
- Bridge originally constructed in 1848
- Ballasted precast concrete deck panel system installed
- Supports expanded freight and passenger service
- ACEC Massachusetts Engineering Excellence Award
