Leaders in Montgomery and Fairfax counties, concerned about massive congestion expected to surge on the American Legion Bridge later this year, have requested that state transportation officials permit exclusive bus lanes there or allow motorists to use the shoulders during peak hours.

However, transportation officials said they question whether either option would fix the traffic pain that local officials on both sides of the Potomac River have predicted with the opening of Beltway express lanes in Virginia.

The new high-occupancy toll, or HOT, lanes end just north of the Dulles Toll Road, and drivers are expected to hit a bottleneck at the bridge, where the Capital Beltway enters Maryland, causing traffic backups, especially for those who work in Virginia and drive home to Maryland in the evening.

The traffic quandary has created strange bedfellows, as Montgomery and Fairfax counties -- Potomac rivals entangled in a constant scramble for jobs -- are joining forces to push state officials to implement a short-term fix that would keep already lengthy commutes from getting even worse.

"[W]e urge you to review options for peak hour use of shoulders as exclusive bus lanes or opening the shoulder for general purpose traffic and establishing an HOV lane in the outside lane during peak periods, similar to I-66," a new letter penned by Fairfax County Board of Supervisors Chairwoman Sharon Bulova and Montgomery County Council President Roger Berliner said.

But transportation officials say a host of questions remain about whether the blueprint pushed by Montgomery and Fairfax leaders is feasible.

"We're not quite there yet," David Buck, spokesman for the Maryland State Highway Administration, said, adding that state officials needed a few more months to find a short-term fix to ease traffic there. "There are some challenges, and we don't know if they can be overcome yet."

Maryland officials also are working on ways to alleviate congestion on the Beltway between the Dulles Toll Road in Virginia and the west I-270 spur in Maryland over the long term, but Montgomery and Fairfax say they need help in the meantime.

However, Buck said that shoulders along interstates are not constructed to handle traffic since they're designed as emergency lanes. He also said that any such reconstruction would come at a "substantial cost."

Local officials agree that some kind of bus service is needed to help commuters moving across the bridge, which carried 232,000 vehicles a day in 2010.

Berliner said the brewing problem at the bridge is emblematic of a transportation predicament engulfing Montgomery County, the economic engine of Maryland.

"We desperately need transportation funding in the state," he said. "If the state is unwilling to step up and provide this funding, we need to understand the consequences. 'No' is not an acceptable answer."