Workers recently broke through the end of a 1,000-foot tunnel being built to carry Purple Line trains beneath a neighborhood in the Long Branch area of Silver Spring. (Evelyn Hockstein/For The Washington Post)

A federal judge on Tuesday dismissed a second lawsuit brought by opponents of the Purple Line, saying they hadn’t proven an “injury” under the law that they argued federal officials had violated in awarding $900 million in federal construction aid to the Maryland light-rail project.

U.S. District Court Judge Richard J. Leon also ruled that the plaintiffs were too late in filing a claim related to the project’s potential impact on historical sites.

Leon rejected the opponents’ argument that they would suffer “injury” as Metro riders because the Purple Line would take money and resources away from the region’s aging subway system. Leon agreed with government lawyers that the $900 million awarded by the Federal Transit Administration had not been diverted from Metro’s rehabilitation.

The lawsuit was filed by Chevy Chase residents John M. Fitzgerald and Christine Real de Azua, Bethesda resident Anna C. Haac, and the Friends of the Capital Crescent Trail advocacy group.

Fitzgerald, an environmental lawyer, said Tuesday that he hadn’t read the ruling and didn’t know if he and the others would appeal.

The 2017 lawsuit received far less public attention than the opponents’ first lawsuit filed in 2014 on environmental grounds. The initial lawsuit delayed the Purple Line’s construction start date for almost a year before an appeals court rejected it.

In the second lawsuit, opponents argued that federal transit officials hadn’t considered Metro’s “financial crisis” when they determined that Maryland could afford to pay its share of the Purple Line, which is projected to cost $5.6 billion over 36 years. The opponents also said government officials hadn’t properly considered the project’s impact on a historic post office in downtown Bethesda and a historic bridge in the Lyttonsville community of Silver Spring.

A third lawsuit filed in January by two of the same opponents is pending in U.S. District Court for the District of Maryland. In that lawsuit, the opponents argue that the U.S. Army Corps of Engineers improperly allowed Purple Line construction work that will harm streams and wetlands.