DDOT Long Bridge Replacement, Environmental Impact Statement

Serving as the only railway link between Virginia and the District of Columbia, the Long Bridge is a two-track railroad bridge over the Potomac River used by Amtrak, Virginia Railway Express, CSX Transportation, and Norfolk Southern. The Long Bridge project proposed improvements along the rail corridor to achieve four-track capacity, more reliable service, and better infrastructure for this critical thoroughfare.

Options under consideration included replacing the Long Bridge, which was constructed in 1904, replacing or constructing several rail and pedestrian bridges along the corridor, as well as improving related track infrastructure. The plan to build a more connected, green, and sustainable region required the preparation of an Environmental Impact Statement, and Schnabel was a member of the team responsible for its development.

Our role involved providing concept-level geotechnical recommendations and evaluating geotechnical risks to support an alternatives evaluation and concept development of the proposed Long Bridge corridor improvements. The project scope extended from the Rosslyn Interlocking in Arlington, Virginia, to the L’Enfant Interlocking near 10th Street SW in the District of Columbia. We performed a desktop study of historic geotechnical information to characterize the subsurface conditions along the corridor and catalog the data for future project use.

Using the data we gathered during the desktop study, we developed concept-level geotechnical recommendations for new bridge foundations, retaining walls, and embankments proposed across the corridor using the available historic geotechnical information. We evaluated several options to mitigate embankment settlement, including ground improvement at new or widened bridge approaches. We also supported the selection of the preferred alignment by evaluating geotechnical risks along the corridor and potential impacts to existing structures from various alignment alternatives.

^{Photo: Leandro Neumann Ciuffo}