Maryland officials are scrambling to find another strategy to finance the $425 million expansion of an aging Baltimore freight rail tunnel, following CSX Transportation’s withdrawal from the project earlier this month.

Increasing the clearance inside the 120-year old, 1.4-mile Howard Street Tunnel to accommodate double-stacked container loads was considered essential to helping the Port of Baltimore compete with other East Coast ports for a share of post-Panama Canal expansion shipping traffic. Volume has already been on the rise, with 908,000 20-ft-equivalent container units passing through Baltimore during the 12-month period that ending June 30. A nearby 356-acre waterfront site, purchased by the state in May, was being eyed for the first major expansion of the port since the 1980s.

CSX, based in Jacksonville, Fla., had also agreed to a plan to split nearly two-thirds of the tunnel’s expansion cost with Maryland, with the remainder to be funded by a federal grant. But in a statement that characterized the move as a “business decision,” the railroad said the project “no longer justifies the level of investment.” No specific justification for the decision was provided

The railroad has undertaken other infrastructure projects in the region, including improving the 3,800-ft Virginia Ave. Tunnel in Washington, DC. That project, approximately midway through its 42-month construction schedule, is replacing a 1870s-era single-track tunnel with two new tubes that can accommodate double-stacked container trains. CSX is funding the project’s entire cost, estimated at $250 million.

Maryland officials hope to learn more about the railroad’s change of heart while it examining other funding options, such as assuming a larger share of the construction cost.