Amtrak’s $6B Baltimore Tunnel Project Moves Closer to a Faster Northeast Corridor

KEY POINTS

• Amtrak is replacing its 153-year-old Baltimore & Potomac (B&P) Tunnel with a $6-billion twin-tube Frederick Douglass Tunnel, the railroad's largest-ever infrastructure investment.

• Crews have completed excavation and initial footings on the West Mulberry Street bridge, broken through a 345-foot utility siphon tunnel, and advanced manufacturing on two tunnel-boring machines while excavating a 60-foot-deep south portal launch pit.

• Amtrak and the Federal Railroad Administration eliminated a planned intermediate ventilation facility and raised parts of the tunnel alignment 10 to 22 feet to cut costs; tunnel boring is set to begin in 2028, with the Frederick Douglass Tunnel targeted to open in 2036.

Construction activity is accelerating on Amtrak’s $6-billion Baltimore & Potomac (B&P) Tunnel Replacement Program, one of the most ambitious rail infrastructure projects in North America.

The project will eliminate one of the most notorious bottlenecks on the Northeast Corridor and pave the way for more reliable passenger rail service between Baltimore, Washington and Virginia.

Why is the B&P Tunnel being replaced?

A key element is the replacement of the existing B&P Tunnel, a structure that dates to 1873 and remains Amtrak’s oldest tunnel. The aging tunnel is a critical link on the busiest passenger rail corridor in the United States, serving millions of passengers each year.

However, the deteriorating condition of the tunnel, water infiltration, capacity constraints and tight curves have made it a major source of delays. Trains are forced to slow to 30 mph through the tunnel.

What will the new tunnel system look like?

The replacement project, Amtrak’s largest-ever single infrastructure investment, will ultimately deliver a twin-tube tunnel system known as the Frederick Douglass Tunnel. The new route will remove a bottleneck on the Northeast Corridor and support speeds of up to 100 mph.

“Replacing the 153-year-old B&P Tunnel is critical to improving safety and reliability along the Northeast Corridor, America’s busiest passenger railroad,” explained Amtrak president Roger Harris. “This investment is advancing with a clear path forward as we work toward opening the new Frederick Douglass Tunnel in 2036.

“Successful delivery of this program will continue to rely on support and collaboration from all our partners to address and mitigate current and future challenges.”

Contractors have completed excavation work and installed initial footings for the bridge over West Mulberry Street, with concrete placement and bridge stabilization work now underway. Image: Amtrak

What construction progress has been made so far?

The first major construction contract was awarded in late 2023, with utility relocation efforts launching in 2024. Since then, significant progress has been made across multiple areas of the project.

One visible achievement has been reconstruction of the West Mulberry Street railroad bridge, the first of five bridges that must be rebuilt to accommodate the future rail alignment. Contractors have completed excavation work and installed initial footings, with concrete placement and bridge stabilization work now underway.

What's happening with the siphon tunnel and the TBMs?

Elsewhere, crews have reached a key milestone on a 345-foot-long utility siphon tunnel beneath the Northeast Corridor tracks. The contractor recently broke through the final section of rock pillar separating both sides of the tunnel, using controlled blasting.

The siphon tunnel is an essential enabling project for the Frederick Douglass Tunnel. It will carry water, sewer, communications and electrical infrastructure beneath both the existing and future railroad tracks.

The utility tunnel is considered an essential enabling project because existing municipal services must be relocated before major tunnel excavation can begin. Work now shifts toward rerouting utility lines through the new structure and reconnecting them to Baltimore’s municipal systems.

Meanwhile, manufacturing is advancing on the two giant tunnel-boring machines (TBMs) that will excavate the new tunnel tubes. The first machine is now more than 50 per cent complete and remains on track for deployment in 2028.

Construction has also begun on a massive south portal launch pit, a 60-foot-deep excavation that will serve as the starting point for the tunnel boring operation. Once excavation is completed, the enormous TBMs will be lowered into the pit and assembled underground.

The coming months will see extensive excavation, piling and site preparation work around the launch area as crews prepare for the transition from enabling works to full-scale tunnelling.

Utility relocations are ongoing throughout the corridor, particularly near the future North Ventilation Facility and north portal area. At West Baltimore MARC Station, construction is progressing on a relocated bus loop and related accessibility improvements.

What other bridge and utility work remains?

Additional bridge replacements remain ahead of schedule. Along with the Mulberry Street structure, crews must replace railroad bridges at Franklin Street and Warwick Avenue as well as roadway bridges at Edmondson Avenue and Lafayette Avenue. The Lafayette Avenue bridge replacement will require a complex multi-phase construction sequence and temporary relocation of nearby park space.

To improve affordability and constructability, Amtrak and the Federal Railroad Administration have spent more than a year reviewing potential design optimizations. Several refinements have now been incorporated into the project without changing its overall scope.

Among the most significant changes is the elimination of a planned intermediate ventilation facility and its connecting tunnel, reducing both cost and community impacts. Engineers have also modified the tunnel alignment by raising portions of the route between 10 and 22 feet, reducing excavation volumes while maintaining required safety standards.

Other changes include resequencing work and expanding opportunities for parallel construction activities.

When will tunnel boring begin?

Despite the progress, substantial work remains before tunnel boring begins. Crews continue soil stabilization, jet grouting, sewer installation, roadway modifications and site mobilization activities throughout the project corridor.

Once tunnelling begins in 2028, the two TBMs will excavate separate tunnel tubes beneath Baltimore, creating the backbone of a new rail corridor designed to serve the region for decades to come. Following tunnel excavation, crews will install tracks, power systems, communications infrastructure, ventilation equipment and life-safety systems before the line enters service.

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