Financing for the $2.8-billion second leg of a northern Virginia rail transit line to run to Washington Dulles International Airport and beyond has taken a step forward with the closing of a $1.3-billion federal loan.

The U.S. Dept of Transportation said on Aug. 20 that it had closed a $1.28-billion Transportation Infrastructure Finance and Innovation Act (TIFIA) loan with the Metropolitan Washington Airports Authority (MWAA), which operates Dulles and Ronald Reagan Washington National airports and also is in charge of the rail project’s construction.

The closing covers the largest portion of an overall $1.87-billion TIFIA loan for the rail extension. Still to come are U.S. DOT closings with Virginia’s Fairfax and Loudoun counties for the remaining $600 million of the package.

DOT says that the $1.87-billion loan for the Silver Line is the largest to a single project in TIFIA’s history. Congress launched the loan program in 1998.

The loan will help finance phase two of the Silver Line, which is operated by the Washington Metropolitan Area Transit Authority. Phase two will extend the Silver Line 11.4 miles and include six new stations, including one at the airport.

The $2.9-billion phase one, which opened on July 25, is 11.7 miles long and runs from the East Falls Church Metro station to the Reston, Va., area.

MWAA on May 14 awarded a contract to a design-build team of Clark Construction Group and Kiewit Infrastructure South Co. for the major part of phase two. The joint venture, called Capital Rail Constructors, submitted a $1.2-billion proposal for the work, the lowest among five bidders.

MWAA spokesman Christopher Paolino says that phase-two construction has begun, including initial drilling for pylons supporting an aerial section of the line at Dulles airport. He says phase two will take about five years to complete.

Paolino also says that the closing of the authority’s part of the TIFIA loan “is extremely important.” He says, “It allows us to secure financing for the project well below the market rate we’d get if we…had to go to the bond market.”

Paolino says that will mean “significant savings,” especially for motorists on the nearby Dulles Toll Road. Their tolls will cover a large portion of the rail project’s cost. He says the TIFIA loan will allow the authority to keep toll levels constant for five years.

DOT Secretary Anthony Foxx said in a statement, “The first phase of the Silver Line has been an overwhelming success, and we look forward to ensuring the second half is just as successful, with the help of this $1.28 billion [loan] from the federal government.”