Virginia is moving toward putting express lanes -- or possibly rail -- along traffic-clogged Interstate 66.

The commonwealth next month plans to issue a request for ideas from companies on how to install tolled express lanes, bus or rail along the highway, from the Capital Beltway to Gainesville, Virginia Secretary of Transportation Sean Connaughton said Tuesday.

The Northern Virginia highway is notorious for its stop-and-go traffic. State officials in February finished a study that found most of its traffic during morning and evening rush hours usually travels at no more than 30 mph.

The study also found the state would have to add a dozen extra lanes to parts of the highway to keep traffic flowing freely through 2040, if it didn't find another solution, like express lanes or transit.

Connaughton said that after the state receives ideas from private companies, the Commonwealth Transportation Board will choose which solution for I-66 it wants to pursue -- express lanes, rail, bus or a combination -- and then conduct further study and find a contractor.

Though some Northern Virginia leaders support extending Metrorail along the highway, Connaughton has said that he thinks it would be logical to connect express lanes on Interstate 66 with the Beltway Express Lanes. Express lanes charge a toll for a congestion-free ride but offer a free trip to carpoolers with a special E-ZPass tag.

"We think having [an express lanes] system that ties into Northern Virginia, and hopefully someday Maryland, will be great for the whole region," Connaughton said Tuesday.

New express lanes would be limited to a 25-mile stretch of the highway outside the Beltway, but the lanes would have to extend to the District eventually, even if local leaders oppose them, Connaughton warned at an event with regional transportation leaders Tuesday.

"If you don't want us to widen the road, then we're going to have to figure out a way to get more capacity out of the road, and I think express lanes are a way to do it," Connaughton said. "The jurisdictions inside the Beltway are essentially erecting a fence. They're very focused on Metro, which is a positive thing, but at the end of the day, you have to have a balanced transportation system."

Arlington County in 2009 sued to block similar express lanes planned for Interstate 395 from crossing its borders.