The Utah Transit Authority has released its "best estimate" schedule for when four new TRAX light-rail lines will be built and commuter rail extended to Provo.

The transit agency met Wednesday with a subcommittee of its board of trustees to give an update about the status of the rail projects and outline a tentative financial plan for construction. Since November, when residents of Salt Lake and Utah counties approved separate quarter-cent sales-tax increases for the transit lines, UTA has worked to finish studies and plans for the rail lines.

All five lines are estimated to cost about $2 billion and are projected to be finished by 2015. First on the list for completion is the mid-Jordan TRAX line, slated for 2011.

Mike Allegra, UTA's assistant general manager and chief capitol development officer, said he was hesitant in announcing completion dates, because contractors selected to build the lines could change the time lines. UTA has already released some bids to build the rail projects and anticipates it will have contractors selected by the end of the year.

"We're bringing on the contractors now so we can get their input," Allegra said. "Depending on construction and what they tell us, things could change."

But for now, the mid-Jordan TRAX line remains first on the list, after which UTA anticipates completing commuter rail from Salt Lake City to Provo and the West Valley TRAX line by 2012. TRAX lines to the Salt Lake City International Airport and Draper are expected to be done by 2014.

Most of UTA's expenditures on the project are anticipated to happen between 2008 and 2011, according to Ken Montague, UTA general manager of support services. The agency believes it has the capacity to bond for the projects and complete them by 2015, although cash flow at some times could be tight, Montague said.

"Can we do this — borrow the funds — and complete the projects?" Montague asked board members. "We believe that we can."

UTA's finance plan could involve a number of bonding strategies, ranging from variable-rate bonds to restructuring current debt to build the lines. Several bond rating agencies will visit UTA this month to review UTA's system and help the agency determine how best to finance construction.

Allegra said he is confident that the agency is making good progress. "In my opinion, the majority of the work is what you do in advance of construction," he said.

In addition to planning for the five new rail lines, UTA is now constructing an extension of its north-south TRAX line to the Salt Lake City Intermodal Hub. Construction on the extension is scheduled for completion in 2008. The TRAX line will serve as a connection to UTA's commuter-rail line, the FrontRunner.

A 44-mile segment of commuter rail from Pleasant View, in Weber County, to Salt Lake City is now about 75 percent complete and also is scheduled to be finished in 2008.

On Monday, UTA finished welding a 35-mile continuous segment of rail for commuter rail from Salt Lake to Ogden. The agency said it could begin testing trains on that 35-mile segment as early as next week.