Building a 2.25-mile rapid-transit route for buses in Arlington’s Crystal City corridor could cost at least $10.26 million, and that’s before the bus lanes are converted to a streetcar line, county documents show.

The Arlington County Board will vote Saturday on whether to award a general construction contract to W.M. Schlosser for the project, which has been planned since 2001. Schlosser’s bid was the lowest of three, at $9.9 million, but adding in a cushion for contingencies pushes the bid to $10.26 million.

Separate contracts and fees connected to the transitway — which will not be voted on Saturday — would increase the total cost by $1.7 million.

The project will create lanes dedicated to rapid transit on a route roughly one block over from and parallel to Jefferson Davis Highway, from 15th Street South to just south of South Glebe Road. Buses would turn around at Four Mile Run, just over the bridge from Alexandria’s bus transitway, which is already under construction.

[See a map of the route.]

Ultimately, Arlington and Alexandria hope to connect the two bus routes so that passengers can travel from the Braddock Road Metro station in Alexandria to just beyond the Crystal City Metro station at 18th Street South. Arlington officials, who plan to eventually convert the Crystal City transitway to a streetcar route, then want to connect the planned Columbia Pike streetcar line to this one.

The Crystal City project is being paid for with state and federal funds; the county’s transportation capital fund, which comes from a real estate tax on commercial and industrial land in the county; and developers in the Potomac Yard area.

A separate construction management contract, not subject to the approval of the Arlington County Board, will cost $937,000, and a third contract, to make glass windscreens, will cost $205,000. An independent inspection service will cost an additional $90,600. The cost of county staff and technical support will add another $551,000.

Alexandria’s portion of the bus transitway is expected to be in operation this summer. The 2.5-mile route will cost about $21 million, including the cost of the buses, stations and roadway.

This past spring, Arlington officials were surprised by public outrage at the $1 million price tag of a glass-and-steel “super-stop” for buses, and ultimately streetcars, along Columbia Pike.

Peter Rousselot of Arlingtonians for Sensible Transit, a citizens’ group opposed to the construction of the Columbia Pike streetcar, said that his group hasn’t taken a position on the Crystal City project, although “we support the idea of a [bus rapid-transit] service and an integrated regional system.”