Heavy traffic is seen during rush hour in Vienna headed westbound on Interstate 66. (Marvin Joseph/The Washington Post)

If you take a bus that uses Interstate 66 to get you to your destination, you could soon experience some relief from the traffic congestion that plagues the corridor.

The Virginia Department of Transportation is launching a new program this fall that will allow buses traveling I-66, inside the Beltway, to use the shoulder when traffic is backed up.

The Bus-on-Shoulder pilot program, expected to start in mid-November, is part of a new strategy to improve the commuting experience of transit users in the delay-prone corridor. Transportation officials say it could help save bus riders time and improve the performance for many bus routes that are often stuck in traffic gridlock during the morning and evening rush hours— and increasingly during non-peak times too.

About 30 buses travel the corridor during each rush hour when traffic congestion is generally at its worst. During the pilot, those buses will be able to move to the shoulder lane when traffic speeds drop below 35 miles per hour. Buses using the shoulder will need to maintain a speed of 25 miles per hour.

The one-year pilot follows years of study on how to improve I-66. “Everybody knows that there is a lot of congestion there,” said Bud Siegel, the project manager with VDOT. He said bus-on -shoulder operations are a low-cost strategy the agency can employ to mitigate congestion.

The concept is not new to the region.VDOT began a similar operation along the Dulles Connector in 2000. Shoulder operations also have been successful in more than a dozen states across the country. The Minneapolis-St. Paul region has put nearly 300 shoulder-miles in operation for buses since its program began program 20 years ago. VDOT officials say the I-66 pilot is modeled after the Minnesota program.

In addition to being one of Northern Virginia’s most congested corridors, I-66 also is known for its unpredictability. The 7.4 miles of shoulder lanes should provide a measurable improvement for bus commuters, officials said.

Nick Perfili, section chief for the Fairfax Connector, projects a potential time savings for several of the county’s bus routes, including a route that travels to the Pentagon via the Dulles Connector Road and I-66. Other buses that take I-66 from the county bus garage to their first stop should potentially improve their ontime arrivals.

“I think the whole world is stuck in traffic in this area,” Perfili said. “We will benefit in the morning, in the afternoon and evening commutes. We are going to see improvements in the reliability of travel time in the corridor.”

Metrobus, Loudoun County Transit, and the Potomac and Rappahannock Transportation Commission also use I-66 and would benefit from the pilot too.

VDOT is finalizing agreements with each transit agency that spell out the rules for use. The state has identified these four sections of I-66 where buses will be able to safely use the shoulder:

• Eastbound Dulles Connector extending the existing bus-on-shoulder operation which ends at the ramp to the West Falls Church Metro station to the merge onto eastbound I-66 near the Great Falls Street overpass.

• Eastbound I-66 from the U.S. 29 overpass near Spout Run Parkway to North Quinn Street.

• Westbound I-66 from beyond the Rosslyn Tunnel (North Nash Street) to the U.S. 29 overpass near Spout Run Parkway

• Westbound I-66 from the North Quincy Street underpass to the auxiliary lane beyond North Fairfax Drive (beyond Exit 71).

Only authorized transit buses will be allowed to travel on the shoulders. Shoulder use for emergencies will continue to be a priority, officials said.

Crews are finishing up work on the shoulders in preparation of the pilot launch, Siegel said. In some locations, workers have paved over what used to be gravel, relocated mile-marker signs and installed new signs indicating that buses can use the shoulder. In some portions of the corridor, shoulders have been widened and trees have been trimmed. The improvements have cost about $600,000 and were paid for by the state, officials said.

As the region’s traffic congestion continues to challenge transit service, regional transportation officials say similar bus-on-shoulder operations are options to be considered as cost-effective strategies to make bus travel more attractive and efficient and ultimately increase transit ridership.