Government officials in the Washington region, as well as nationwide, are looking increasingly to bus rapid transit for new transit options as they face tightening public purses.

BRT plans are under way in Alexandria and Arlington County, where buses are planned to travel from Braddock Road to Pentagon City.

Alexandria expects to begin construction in July and start running buses in dedicated lanes in December 2013, said Abi Lerner, Alexandria's deputy director of transportation. Arlington expects to complete its half of the system in spring 2014.

Across the Potomac, Montgomery County officials have proposed a 160-mile system with 23 routes. The system is expected to cost at least $1.8 billion and take as many as 20 years to build.

Officials in both areas say BRT's advantages over rail include a comparatively lower cost and shortened building time frame.

Maryland Gov. Martin O'Malley approved BRT for the Corridor Cities Transitway, a 15-mile transit system traveling north from the Shady Grove Metro station along Interstate 270, citing cost as a major reason. Using BRT, the system is expected to cost $491 million. With light rail -- the original choice -- the price of construction increases to $772 million.

"We just simply don't have the money to do everything that we want to do," said Marilyn Balcombe, chairwoman of the CCT Coalition and a self-proclaimed recent BRT convert. "There are no federal dollars. There are no state dollars. And there's a desperate need."

Cost aside, advocates argue BRT is simply better -- just as fast as rail but more flexible, said Montgomery County Councilman Marc Elrich, D-at large.

If the county invests in high-end stations and dedicated guideways, developers will see the systems as permanent additions, Balcombe said.

But not everyone agrees.

"The critical issue for light rail is that it is absolutely fixed route transportation, and as such it encourages people to invest in development right next to it," said Ralph Bennett, president of Purple Line Now, which advocates for the 16-mile light rail planned to connect Bethesda to New Carrollton. "You do not find that same kind of real estate value increase next to BRT."

Buses also have a "PR problem," Balcombe added, expressing concerns that people will avoid BRT because of aversion to buses.

In Arlington, a new analysis found that replacing the planned streetcar on Columbia Pike with BRT would reduce the cost from more than $214 million to $47 million. But officials are not expected to change course, said spokeswoman Mary Curtius.

An anti-bus mentality is unproductive, said Robert Puentes, a senior fellow at the Brookings Institution's Metropolitan Policy Program.

"People will make rational decisions about how they travel regardless of mode," he said. "We can't just be fixated on one mode to the exclusion of others."