The Federal Transit Administration this month spurned supporters of a Metrorail tunnel under Tysons Corner in two separate reports, challenging the quality of multimillion-dollar engineering work for the underground track and refusing to open up the proposal for new consideration.

The conclusions from the FTA represent another blow to the local movement to bring back the tunnel plan and demonstrate the agency’s unwillingness to entertain serious changes to the Dulles Corridor Metrorail Project this late in the planning process, as well as their lack of faith in the independent tunnel engineering.