The board of directors of Denver’s Regional Transportation District approved last month a public-private partnership consortium’s $2.085-billion proposal to build and operate 44 miles of new commuter rail, including a line serving Denver International Airport.

Denver Transit Partners is sponsored by Fluor Enterprises Inc., a division of Irving, Tex.-based Fluor Corp., and Australia’s Macquarie Capital Group Ltd. They are joined by partners Ames Construction, Balfour Beatty Rail Inc., Alternate Concepts Inc. and HDR Inc.

The proposal came in $300 million lower than RTD’s budget estimate of $2.4 billion for the Eagle P3 project. The bid also promises to open the central line between Denver and DIA by January 2016, 11 months ahead of RTD’s deadline.

The competing bidder was a consortium known as Mountain-Air Transit Partners, which included Siemens, Veolia Transportation, Kiewit and HSBC Bank.The two teams spent two years working on proposals. RTD will pay the Mountain-Air Transit Partners a $2.5-million stipend in exchange for the intellectual property in its proposal.

Voters had approved a ballot measure in 2004 to fund the fast-tracked transit program, called FasTracks, through sales- tax increases. Since then, the estimated cost for building 122 miles of rail and 18 miles of bus rapid transit has risen to $7 billion from $4.7 billion and sales-tax revenues have fallen short of projections. “We said three years ago that public-private partnerships would be a vital part of keeping our FasTracks program moving forward,” said RTD Chairman Lee Kemp at the June 15 board meeting.

The first stages of construction, which include relocation of utilities and freight tracks along the DIA route, are slated to begin before summer’s end. The Eagle P3 project will design and construct the 11.8-mile east corridor to DIA, the 11.2-mile Gold Line north and west from downtown, a short segment of the Northwest Rail corridor to south Westminster and a commuter-rail maintenance facility.

Denver Transit Partners also will operate and maintain rail service on the lines for 40 years, receiving annual performance-based payments from RTD.

FasTracks faces a $2.4-billion gap, although in its 2010 annual program evaluation RTD estimates the overall cost has dipped to $6.5 billion. In addition to pondering a potential second ballot measure for another sales-tax increase, RTD expects the project to attract $1 billion next year through the Federal Transit Administration Full Funding Grant Agreement process.

A task force was created in 2009 to look at getting out requests for proposals for the remaining FasTracks corridors before this November, when a second ballot measure to increase sales taxes might occur. “We want to lock in an idea of the costs of those corridors,” says RTD general manager Phil Washington. With the P3 award, RTD will have 47 miles of new rail under construction or under contract, representing nearly 40% of the total FasTracks network.

A joint venture of Herzog Contracting Corp., St. Joseph, Mo., and Stacy and Witbeck Inc., Alameda, Calif., is well under way with its $343-million contract for the west corridor, a 12.1-mile segment of FasTracks. It is the first of the lines in construction; work began last year and is slated to finish by 2013. The project includes 500,000 sq ft of retaining wall, 12 stations and 14 major bridges, including a 1,540-ft structure with a 240-ft-long cast-in-place box-girder main span, says John West, DTCG project manager.