Metro is forecasting that the first segment of the Silver Line currently under construction will cost $112 million to operate over the next three years, including fuel and energy costs.


But riders' fares are expected to pay for only $47 million of that, leaving an estimated $65 million bill on the table for local jurisdictions and taxpayers.

Even once the trains run for a full year -- expected in fiscal 2015 -- the agency is expecting a $16 million gap between revenue and expenses. Riders' fares would cover a smaller share of the costs than elsewhere in the system, an agency report says, covering 66 cents for every dollar in expenses compared with the 71 cents covered per dollar in the entire system.

Leaders in Loudoun and Fairfax counties earlier this month asked for estimates of how much it will cost them to run the new Metrorail line before they have to decide whether to fund construction of the second phase, which would extend the line to Washington Dulles International Airport and beyond.

Fairfax County supervisors specifically wanted to know the costs over the next 15 years -- both with and without Loudoun's involvement in case its neighbor pulls out. Northern Virginians are already paying a sizeable share of the construction costs that could top $5 billion if the full 23 miles are built.

The report, slated to go before Metro's board of directors on Thursday, offers the first peek of how much ridership will offset the operating expenses. But it doesn't break down how much each jurisdiction would be expected to pay. The transit agency divvies up costs based on a formula that takes into account ridership, population and the number of stations in the area.

Metro estimates riders will take 14.4 million trips per year on the first 11 miles of the line. Nine million of those trips would be made by new riders. The remaining 5.4 million would be riders who already take Metro and modify their current routes, which doesn't add much fare revenue.

The first two years for the Silver Line may be the toughest for the new rail line, because costs will mount before trains start running in December 2013.

To get ready, the agency plans to hire 363 new workers in the next fiscal year that starts July 1, including 107 track and rail car mechanics, 12 train operators, 23 station managers, 26 cops, plus gardeners, plumbers and masons.

That means Metro and its partners are on the hook for covering $20 million in fiscal 2013 for startup costs, then an estimated $29 million the next year when trains run for six months.