Baltimore’s Red Line light-rail transit project has jumped over a bureaucratic hurdle, winning federal approval to begin preliminary engineering of the 14½-mile east-west route.

The Federal Transit Administration will formally notify the Maryland Transit Administration (MTA) this coming week that there is enough ridership and financial information to begin detailed planning and preliminary engineering, including federal and state environmental impact statements.

The FTA estimates that the transit line will cost $2.2 billion, or $400 million more than the prior estimate of $1.8 billion. The new number includes the projected cost of inflation during the years of construction, 2016-2020. The $1.8 billion figure was based on 2009 dollars.

The FTA did not award any federal money to do the preliminary engineering. But the agency’s notification says the federal government expects to pay 50% of the project’s construction cost out of its New Starts transit fund, with the remaining $1.1 billion coming from the state. The state’s portion would come from the Maryland Transportation Trust Fund supported by motor fuel taxes and vehicle registration and drivers license fees.

The controversial line – supported by Gov. Martin O’Malley, Mayor Stephanie Rawlings-Blake and downtown business interests – would go from the Social Security Administration complex in Woodlawn to the Johns Hopkins Bayview Medical Center.

The line would run mostly in the median strip of existing roads with a one-mile tunnel under Cooks Lane and a three-mile tunnel between Martin Luther King Blvd. and Boston Street through downtown, Harbor East and Fells Point.

The line is expected to transport about 48,100 weekday riders in its opening year (2020) and 50,700 riders by 2030, according to the FTA’s notification letter.

This figure is down from the 60,000 daily riders originally projected by the MTA in its application for federal funding as a New Starts project.