Construction on CSX’s Howard Street Tunnel in Baltimore has reached substantial completion, nearly two years ahead of the original August 2027 target. The $450 million project, managed by a joint venture of Skanska and Fay under S&B USA Construction, is part of CSX’s broader efforts to remove clearance limitations for double-stack freight trains along the corridor between Baltimore and Philadelphia.
The 8,700-foot-long tunnel, originally built in 1895, was raised by two feet—from 19 to 21 feet—without altering its historic brick-and-stone arch. The work involved demolishing and excavating the tunnel floor and installing nearly 1,200 precast concrete slabs, each roughly 18–19 feet wide, through the utilization of railcar-mounted specialized equipment.
Project managers credited the use of a progressive design-build approach for allowing adjustments to engineering plans during construction, reducing costs, and accelerating the schedule. Crews operated around the clock for seven and a half months to complete the work.
Officials said the improvement will increase freight capacity and efficiency on the Mid-Atlantic corridor and into the Midwest, serving the interests of shippers and supporting supply chains connecting the Port of Baltimore.
While the Howard Street Tunnel modernization has been completed, Skanska continues to expand its presence in the U.S., with its latest project being the $323 million Skanska–Flatiron JV contract at Los Angeles International Airport, announced on September 29, 2025.
CSX’s Howard Street Tunnel Modernization Project Completed: Factsheet
Location: Baltimore, Maryland, USA
Owner: CSX Transportation
Construction JV: S&B USA Construction (Skanska + Fay)
Project Value: $450 million
Original Completion Date: August 2027
Actual Substantial Completion: Mid-September 2025
Tunnel Length: 8,700 feet
Original Tunnel Height: 19 feet
Upgraded Tunnel Height: 21 feet
Construction Highlights:
Preserved the original 1895 brick-and-stone arch.
Demolished and excavated the tunnel floor to increase clearance.
Installed 1,200 precast concrete invert slabs, each 18–19 feet wide.
Used specialized railcar-mounted gantry crane for slab placement.
Operated 24/7 over seven and a half months.
Project Methodology: Progressive design-build approach allowing plan adjustments during construction, cost optimization, and accelerated schedule.
Impact:
Increased clearance for double-stack freight trains.
Boosted freight capacity and efficiency along the Baltimore–Philadelphia corridor and into the Midwest.
Enhanced supply chain reliability, including access to the Port of Baltimore.
Extended tunnel lifespan without constructing a new structure.
Key Partners:
Lead Designer: Hatch
Engineering Consultant: WRA
