The Montgomery County Council has changed its mind on what kind of transit line to build in the rapidly growing and heavily congested Interstate 270 corridor, voting Tuesday to recommend a busway over the light rail system it endorsed in 2009.

The unanimous recommendation now goes to Maryland Gov. Martin O’Malley (D) as he considers which mode and route to submit in a highly competitive bid for federal construction money.

A 15-mile Corridor Cities Transitway (CCT) would connect the Shady Grove station at the end of Metro’s Red Line in Rockville with the Clarksburg area, via Gaithersburg and Germantown. The county has targeted much of its future development for the area, and Montgomery officials say it is key to economic and job growth, particularly the county’s ability to continue attracting life science companies. Much of the approved development for the area can’t go forward without a transitway to prevent further traffic congestion.

Affordability and timing seemed to be the biggest considerations for council members. Several cited a recent state study that found a busway, called Bus Rapid Transit (BRT), would provide significantly higher economic benefits than light rail because its lower cost would make it affordable a decade earlier.

A rapid bus system is estimated to cost $491 million to build, while a light rail system is projected to cost $772 million.

“[Bus] rapid transit would occur approximately 10 years faster” than light rail, said Council President Roger Berliner (D-Potomac-Bethesda). “The consequence of that is huge in terms of economic benefit to our county.”

Rick Kiegel, the Maryland Transit Administration’s project manager on the transitway study, said state planners probably will make a recommendation on the mode and route to Maryland Transportation Secretary Beverley Swaim-Staley by early February. He said the governor is expected to make a decision by April.

Kiegel said state planners are leaning toward a busway because buses would have more flexibility to get into the upcounty’s more sprawling subdivisions. A busway also would jibe with local plans to build a countywide network of bus lanes.

Consensus among local and state officials is considered key in the federal competition for scarce transit construction money because any plan would need significant statewide support to come up with the state’s half of the construction funds.

The council had previously voted 6 to 3 to endorse light rail, a far more expensive option that state transit planners have since said would take an additional 10 to 12 years to build because of its higher price.

Council member Craig Rice (D-Upcounty) said upcounty residents want to feel more connected to the rest of Montgomery.

“This provides a reliable and more time-effective way to get people out of their cars and use mass transit,” he said.

Montgomery Executive Isiah Leggett (D), who had previously endorsed light rail, changed his mind in December.

“I would personally like to see light rail, but . . . I would like to see it during my lifetime,” Leggett told an audience at a public meeting in Germantown on Monday.

State transit planners say buses would run in their own lanes to avoid traffic congestion and would look much like trains on rubber tires. The line’s 16 stations would be spaced about a mile apart and have platforms that would allow for quick boarding and ticket machines where passengers would pre-pay.

Staff writer Victor Zapana contributed to this report.