Montgomery County planners designing a proposed rapid transit system are facing the unpleasant choice of further clogging main traffic arteries in the county by taking lanes for bus routes or condemning churches, houses and businesses to build new lanes.

The Planning Department wants to use existing lanes wherever possible and not cut into people's properties, said Mary Dolan, acting chief of the department's Functional Planning and Policy Division. Once the system is in place, the county can go back and build it up, adding additional lanes or even new routes.

Designing a complex, costly system will make getting approval from the County Council and funding from the state more difficult, she said.

And the county will need to claim property in order to replace sidewalks and build bike lanes, which will be required by the State Highway Administration, said Master Planner Larry Cole.

In some parts of the county, roads are so narrow that the county will have to take significant swaths of land just to build the minimum, Cole said. As an example, he pointed to the stretch of Georgia Avenue between the Forest Glen Metro station and Veirs Mill Road.

But failing to build additional lanes means that the buses could get stuck in the county's infamous traffic, said Jonathan Genn, who chairs a county task force work group dealing with the design of the system.

"To the maximum extent possible, we need fully dedicated rapid transit lanes," so that rapid transit buses are not sharing lanes with the rest of traffic, said Genn.

Where the county does not plan to immediately build additional lanes, it should be planning for the future, he said. If they don't claim right-of-way now, property owners might build into the space where the county could one day build more BRT lanes.

County Council President Roger Berliner, D-Bethesda and a Transit Task Force member, declined to comment on whose approach makes more sense, but he shared Genn's vision of building an optimal system.

"If we get to a place where we have compromised [the level of service], then we will have done ourselves a disservice," he said.

To determine whether routes are plausible or whether the county will need to build additional lanes, the Planning Board has commissioned a feasibility study, estimated to be completed before June, when the department expects to have a draft of the system. The public will have opportunities to give their thoughts on the draft before it goes to the county council and county executive in the fall.