A Montgomery County council committee voted unanimously Thursday to recommend building a transit line in the rapidly growing Interstate 270 corridor as a bus system rather than light rail, as the council recommended in 2009.

If the full council endorses a Bus Rapid Transit (BRT) system Tuesday, the recommendation would go to Maryland Gov. Martin O’Malley (D), who will choose a mode and route for a Corridor Cities Transitway. The 15-mile line would run between the Shady Grove Metrorail station in Rockville and the Clarksburg area, via Gaithersburg and Germantown.

The Maryland Transit Administration will submit O’Malley’s choice to the Federal Transit Administration as part of the state’s bid for federal construction funds.

Though the council previously endorsed light rail, members of the transportation committee said they were swayed by a recent state analysis showing that a busway would provide significantly higher economic benefits because it could be built 10 to 12 years earlier than more costly light rail.

State transit planners have said they are leaning toward BRT as the better option because of its lower cost and ability to better serve the more spread-out upcounty. Consensus among state and local officials is considered key to clinching highly competitive federal money. Building a busway in the I-270 corridor also would jibe with another recent proposal to build a countywide system of busways.

A rapid bus system in the I-270 corridor is estimated to cost $491 million to build, while a light rail system is projected to cost $772 million. Under the BRT plan, buses would run primarily in their own lanes to avoid traffic congestion.