On Sept. 26, 2025, an expanded Howard Street Tunnel reopened in Baltimore, Md.

CSX noted that this historic and transformative more than $450 million infrastructure project will modernize freight rail transportation along the East Coast. The project marks a major milestone in the decades of effort by state, federal and private partners to deliver a long-sought boost to Maryland's economy and the nation's supply chain.

"The completion of the Howard Street Tunnel reflects the dedication of our people — a once-in-a-generation achievement that will drive commerce, jobs and growth across Maryland and the East Coast for decades," said Joe Hinrichs, president and CEO of CSX. "This project reinforces CSX's position as a high-performing, customer-focused railroad investing for profitable growth."

Fay photo

The Howard Street Tunnel (HST) stands as a testament to 19th-century engineering and continues to serve as a vital piece of modern infrastructure. Built in 1895 and extended in the 1980s, the brick-lined passage serves as CSX's main North-South rail line along the East Coast. As one of the last remaining single-track segments on the CSX network, it represents a unique challenge and infrastructure opportunity on one of America's busiest freight routes.

To address this issue, CSX awarded a $242 million contract in January 2024 to a joint venture (JV) between Skanska and Fay, S&B USA Construction to lower the tunnel floor to increase clearance, while also improving drainage. This work was performed as part of the overall HST project, a key CSX capital improvement initiative. It will eliminate clearance restrictions for double-stack trains along its vital I-95 rail corridor between Baltimore and Philadelphia, as well as from the Port of Baltimore's Seagirt Marine Terminal Intermodal Container Transfer Facility to consumer markets in the Midwest.

"Not only will this project improve a vital CSX rail corridor, but it will create a ripple effect that will strengthen the Port of Baltimore's ability to compete with other East Coast ports," said Ray Hagen, Fay's deputy project manager. "Its forward-looking improvements are expected to significantly boost productivity at the port and expand freight rail capacity throughout CSX's rail network."

Fay noted that HST is an 8,700-ft.-long brick and stone arch tunnel. It had a clearance of approximately 19 ft., which the JV increased to 21 ft. Due to its status as a historic landmark, the structure could not be removed and rebuilt. Instead, the JV excavated the tunnel's floor to lower the track and installed enormous new pre-cast concrete invert slabs, which will improve the drainage and support the weight of the trains.

Because of space constraints, the JV needed to come up with a customized crane design capable of carrying multiple 20,000-lb. precast concrete invert slabs to be laid along the length of the tunnel bed. The group came up with the initial idea of attaching a gantry crane atop a flatbed railcar, which would allow workers to safely move and efficiently position the slabs on the newly lowered tunnel floor. The final design and machine were the result of the JV's combined ideas and engineering in collaboration with Kelley Engineered Equipment and Wolf Hills Fabricators.

"The idea was to place a gantry crane on a railcar to create a machine that could lift and carry the enormous weight of the pre-cast sections into the tunnel," said Thomas Costabile, Skanska's onsite Construction Manager. "We needed to pre-cast, rather than allowing them to cure inside the tunnel because of CSX's tight construction timeline. Necessity really is the mother of invention."

First, the JV envisioned a single-beam gantry crane built on a train car, but due to the cross slopes inside the tunnel, the side load on the beam would not have been able to handle the loading.

"We ended up going with a double-beam system to allow for horizontal curves," said Ed Chaney, a Fay senior superintendent also involved in the project.

The design allows the crane to extend approximately 30 ft. past the base of the gantry, which makes it possible to set the inverts while also bearing their load.

Fay photo

Powered by electricity from the local grid, he noted that the gantry system is agile and quiet. It also illuminates the tunnel and eliminates the need for diesel generators and trucks transporting loads of equipment and workers in and out of the tunnel. Crews worked around the clock, installing an average of six of approximately 1,190 total segments each day.

The process of placing the concrete invert segments was completed in the following order: all the materials and equipment arrived by rail through the tunnel's eastern portal. Crews started by excavating the floor of the tunnel, removing the original invert and excavating to the desired depth. To do so, the JV used specialized Mecalac excavators, which they chose to work within the confined space.

"The excavators each have a unique two-piece boom with a low profile," said Chaney. "They're designed to swing in a nine-foot, seven-inch radius."

All excavated material was then hauled out in crawler carriers on a rotating chassis to eliminate backing trucks through the tunnel. Once outside the tunnel, the material was transferred into 40-cu.-yd. side-dump gondola cars for the trip to the excavated material placement area, roughly three miles from the tunnel.

While nearly double the length of the average rail car at approximately 120 ft. long, the gantry's structure was compact enough to navigate the curves in the tunnel. The precast slabs were delivered beneath the back end of the crane, which lifted the concrete invert slabs and carried them through the crane to the front, past the base of the gantry. Then, the crane set three slabs, one at a time, in the excavated area. Workers then grouted each section through grout ports to ensure a sound foundation and installed rebar on the sides to cast concrete wing structures. Once those cured, the track was bolted in place, the crane advanced forward, and the whole process was repeated.

CSX coordinated with a nearby railroad via a joint-use agreement, enabling CSX trains to operate on neighboring tracks during construction. With uninterrupted 24/7 access to the tunnel and no interference from live rail traffic, the JV could proceed without delays. The gantry crane solution also played a big role in efficiently advancing the work, and the project finish date was over a full year ahead of the original schedule.

"The JV partners cut two years off this challenging project, with CSX accepting the substantially complete work in mid-September," said Hagen.

This project is a progressive design-build, a collaborative project delivery method in which the design-build team — the JV, plus designers Hatch and WRA — was selected by CSX based on technical qualifications and a preliminary price estimate. Then, the design-build team worked with CSX to further define their needs through a transparent process, which helped establish a guaranteed maximum price at approximately 60 percent design development.

Fay photo

The team noted that this alternative approach adds a level of partnership and results in a well-planned solution and a mutually agreed price instead of basing the cost on the preliminary price estimates. This level of collaboration and teamwork has helped overcome many of the challenges the project encountered, including unanticipated areas of hard rock.

Most of the work on this project was centered in the tunnel. Once the project is fully completed, it is expected to have a lifespan of 75 years.

CSX reported that the tunnel was originally built from 1890-95, serving as a vital artery in America's transportation network for more than 125 years. A press release stated that with the tunnel project completed, and once additional clearance projects are complete in early 2026, a key I-95 corridor bottleneck will be cleared, and double-stacked intermodal trains will move through Baltimore.

"With this upgrade, CSX builds on its record of having the fastest and most efficient freight rail route along the I-95 corridor, giving customers a clear service advantage from Florida to the Northeast," the release stated. The project also unlocks new lane-conversion opportunities, enabling shippers to shift even more freight from highway to rail.

The project came about through a partnership between CSX, the State of Maryland, the Federal Railroad Administration and the U.S. Department of Transportation.

The overall project is expected to provide the East Coast with seamless double-stack capacity on rail. Double-stacking is a more cost-effective way to transport freight by rail compared to trucks, reducing congestion along the busy I-95 corridor, and delivering environmental benefits with less emissions. It will also increase business at the Port of Baltimore by approximately 160,000 containers annually and generate more than 13,000 new jobs. CEG