One of the easiest ways to beat the Washington region’s traffic congestion might soon be to ride the bus — but not the buses of today stuck in the backups.

When traffic bogs down, buses on some highways and major roads might soon be allowed to breeze past on the shoulders.

A group of Washington area public officials and transportation agencies is considering which roads and highways have enough shoulder room to allow buses to bypass backups. Supporters say doing so would lure more people out of their cars by providing a faster and more reliable bus ride. That would be a relatively easy and more affordable way to relieve congestion and move more people than widening roads, they say.

“It’s hard to think of any [traffic relief measure] more within reach without requiring enormous expenditures,” said Arlington County Board member Chris Zimmerman (D), who is co-chairing the task force organized by the Metropolitan Washington Council of Governments.

The group’s other co-chair, Carol Krimm, a Frederick city alderman, said she believes more people would forego the daily stress and expense of driving if they could ride a bus that stayed on schedule. Other congestion relief options — such as widening Interstate 270 between rapidly growing Montgomery and Frederick counties — would cost billions, she said.

“We can’t just sit back and wait for money that’s not coming,” Krimm said.

Buses have been using shoulders to bypass congestion in several cities for 20 years, but the idea has spread in recent years as traffic has worsened and money for major transit and road construction has remained tight.

In the Minneapolis-St. Paul area, which helped pioneer the idea, buses use a network of shoulders spanning more than 250 miles. Other cities that allow it include San Diego, Miami, Atlanta and Cleveland.

In the Washington region, some buses use shoulders on a 1.3-mile section of the Dulles Toll Road near the West Falls Church Metro station and occasionally along U.S. 29 near Burtonsville. A Metrobus route that used the Beltway shoulders on the Maryland side of the American Legion Bridge was discontinued in 2003 because of low ridership.

In most cities with bus-on-shoulder programs, buses are permitted to use the shoulders only when severe backups occur. As a safety precaution, most must travel within 15 mph of the prevailing speed in the regular traffic lanes and cannot exceed 35 mph.

Local transportation experts say the Washington area’s relatively narrow and often curvy and hilly roads could pose challenges. Shoulder space can be tight on highways that have been widened over the years. The area also has many bridges and overpasses that would be difficult to widen enough to accommodate buses, which would create choke points as buses merged into and out of regular traffic. Bus drivers using shoulders also must navigate around vehicles at exit and entrance ramps.

“One issue we really have to look at is how a bus would move in and out of the [regular] travel lanes,” said Nancy Gourley, Loudoun County’s transit chief. “Safety needs to be paramount.”

The council of governments group will determine which roads might be suitable. They would need to have shoulders at least 10 feet wide and pavement thick enough to withstand buses’ heavy loads, said Eric Randall, a council transportation engineer who is assisting the group.

Randall said the panel will focus on the Capital Beltway, Interstate 395, I-66, I-270, I-95 and Route 50. It is scheduled to release its findings in May. The Virginia Department of Transportation is also studying the possibility of allowing buses on the shoulders of I-66 inside the Beltway.

Studies show running buses on shoulders is popular with drivers and passengers, Randall said, but there is limited data showing such programs’ effectiveness.

A study this year sponsored by the Federal Transit Administration found that “the apparent reason for the absence of performance data is that no problems have arisen and the [buses on shoulders] concept appears intuitively beneficial.”

Jack Requa, Metro’s assistant general manager for bus services, said traffic congestion is a leading cause of buses running behind schedule. Backups contribute to Metro buses averaging speeds of 10 to 15 miles per hour, he said. Even cutting five to 10 minutes off a 40-minute bus route could help Metro improve service, he said.

“We’re always looking for ways that high-occupancy vehicles like ours could have any form of priority,” Requa said.

Randall said upgrading shoulders costs between $30,000 and $250,000 per mile, depending on how much they need to be widened or repaved. Expenses also would include signs and police enforcement to keep other motorists off the shoulders.