The governors of Virginia and Maryland announced plans yesterday to study adding express toll lanes to 28 miles of the region's major commuter routes, including large portions of the Capital Beltway, as both states push to build the new-style highways.

Maryland will lead a study on adding toll lanes to 14 miles of the Beltway from Georgetown Pike across the American Legion Bridge and onto Interstate 270 to its juncture with Interstate 370.

Virginia transportation officials will lead a study on adding the lanes to 14 miles of the Beltway from Springfield across the Woodrow Wilson Bridge to Route 5 in Maryland. Officials said that study would consider transit options, because the replacement bridge now under construction is designed to carry Metrorail.

Combined with a plan already underway in Virginia to add toll lanes between Springfield and Georgetown Pike, the three stretches would bring express lanes to about half the 64-mile Beltway, including the entire 22-mile Virginia portion. If a map of the Beltway were a clock face, the lanes would stretch from about 4 to 10.

The studies will cost $1 million each and take about 18 months. It is difficult to say when the lanes would be built, but the minimum time is about five years after completion of the studies. The states could decide to turn the projects over to private companies to speed construction. The lanes already planned in Virginia, to be built and operated by two private firms, are scheduled to open in 2010.

Officials from both states said the lanes would virtually guarantee drivers a congestion-free ride, because tolls would vary with traffic, rising during peak times to control demand.

Drivers would need electronic transponders, such as those used by E-ZPass customers, to enter the new lanes. Gated tollbooths would be unnecessary. Electronic devices would read the transponders and charge motorists' accounts. Signs would tell them how much they were paying.

Whether carpoolers would be allowed to ride free must be decided, officials said.

Virginia favors the high-occupancy toll (HOT) lane system. Carpoolers would travel for free, while solo drivers could choose to pay. Maryland transportation officials favor charging all drivers.

HOT lanes were first pioneered in California a decade ago but have only recently become a popular trend in transportation planning as states look for solutions to traffic congestion. HOT lanes opened this summer in Minneapolis and are under construction in Denver and Houston.

Politicians and planners laud the express toll lanes as a way to give people a traffic-free option, albeit at considerable cost. They also say the concept allows for bus service on highways like the Beltway, because a congestion-free ride permits buses to maintain schedules. They are also attractive because toll revenue can be used to pay for them or to attract private firms to invest in them.

State officials in Virginia have pursued them as aggressively as anyone. Within the last 17 months, the state has announced plans to pursue HOT lanes on its portion of the Beltway and on a 56-mile stretch of Interstate 95 and Interstate 395 between Spotsylvania County and the 14th Street bridge. On Tuesday, a panel of transportation experts plans to recommend to the Virginia Department of Transportation one of two proposals for that project.

"We've tried looking at a referendum approach, we've tried tax reform and we had a transportation component that didn't get included," said Virginia Gov. Mark R. Warner (D). "Folks in the national capital area want action, and HOT lanes are a way to add capacity."

Warner said the close coordination with Maryland was designed in part to ensure that the idea does not fade when he leaves office in January or whenever a new administration takes over in Annapolis.

"I want to make sure this is far enough down the pike that nobody can unwind this," he said after a regional summit in Annapolis with Maryland Gov. Robert L. Ehrlich Jr. (R) and D.C. Mayor Anthony A. Williams (D).

Maryland transportation officials are studying express toll lanes on the rest of the Beltway.

Detractors worry that the lanes are too expensive for low-income drivers -- the estimated cost of a ride in the I-95/395 corridor, for example, is about $13 -- and some say toll lanes amount to double taxation. Carpoolers have come out against the I-95 plan over fears that it will ruin the popular practice of "slugging," in which drivers and riders form spontaneous carpools.

Despite the coordination between Maryland and Virginia, several significant issues remain. Virginia has joined with private firms to finance its HOT lanes, and Maryland officials have not decided how to proceed.

Disagreement over financing methods could make it difficult to build lanes that would run across state lines, because splitting the projects at the border could make them less enticing for investors.

Also, the two states must agree on whether Metrorail or highway lanes make more sense on the Wilson Bridge. Adding rail would leave no space for toll lanes. Rail supporters said they were pleased that the states would study building Metro over the bridge, but said they were concerned that the rush to build express toll lanes elsewhere would lead officials in the region to follow suit.

"HOT lanes themselves are not going to solve everything," said Laura Olsen of the Coalition for Smarter Growth.

Officials said that, even though the studies are coordinated, each state could adopt its own format without slowing drivers. For instance, if carpoolers rode free in Virginia, they would simply be charged a toll like everyone else once they crossed into Maryland.

"Technology used on one side of the bridge will go for naught unless the appropriate technology is on the other side of the bridge," Ehrlich said.

Traffic backs up on the Capital Beltway in Fairfax. High-occupancy toll lanes built by private firms have been approved for this stretch of the highway.