The agency’s February 2025 fact sheet notes the bypass design is about 90% complete, with construction expected to begin this month and finish by 2029.

Jim Schneiderman, FlatironDragados executive vice president, said in a statement the project “will provide safer, more efficient rail service by reducing congestion and improving reliability.” He said the team “will continue to collaborate to ... identify innovative solutions to challenges.”

Agency technical documents show the flyover design uses concrete column piers supporting transverse steel floor beams with cast-in-place composite decks over the CSX freight mainline. The approach spans are designed with longitudinal steel plate girders and steel deck plating.

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This hybrid configuration was selected over deeper longitudinal girder systems to reduce the structure's vertical profile, maintain clearance over freight operations and simplify construction sequencing in a live rail corridor, according to the agency's January 2023 construction industry request for information.

Plans show that the bypass alignment will require approximately 400,000 cu yd of earthwork, embankments, and retaining walls to minimize impacts on nearby neighborhoods. Temporary shoofly tracks will be installed to keep freight and passenger trains running through the corridor during the multi-year build.

Dewatering systems, underground detention facilities and jack-and-bore culverts are planned to manage challenging subsurface conditions, as described in the authority's November 2024 roll maps.

Environmental assessments conducted under NEPA found no significant community impacts, the agency reported; a noise study performed determined post-construction sound levels at nearby homes will remain below 66 decibels, roughly equivalent to conversational noise. The agency stated it coordinated with the U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service and Virginia Dept. of Environmental Quality to address wetland and wildlife considerations.

Multiple Funding Sources

The project is funded through federal, state and local sources, including a $100- million Federal Railroad Administration Consolidated Rail Infrastructure and Safety Improvements grant, Northern Virginia Transportation Authority contributions and Amtrak funds. 

The bypass forms part of the rail agency's Transforming Rail in Virginia initiative, which also includes the Franconia–Lorton third track and Long Bridge North projects.

Scott Norman, executive vice president of Herzog, said the joint venture “looks forward to bringing this project in on time and on budget.”