An advisory panel of regional transportation officials recommended yesterday that Virginia partner with a private firm to build express toll lanes on a 56-mile stretch of Interstates 95 and 395, despite objections from many of the corridor's commuters.

The lanes would stretch from the 14th Street bridge to Spotsylvania County and would have three lanes in the northern half and two in the southern half.

The lanes, known as high-occupancy toll, or HOT, would be free for carpools of three or more people, but others could pay for the privilege of using them. Tolls would increase with the amount of traffic to keep the lanes from jamming.

With yesterday's approval, the proposal moves to acting Virginia Transportation Commissioner Gregory A. Whirley, who will decide whether to build them.

The panel chose a $1 billion proposal led by Fluor Virginia Inc. over one led by Clark Construction Group Inc. Fluor also has an agreement with the state to build HOT lanes on 14 miles of the Capital Beltway.

"I think the benefit of tonight's decision is that there will be one operator on both HOT lane facilities," said Michael Kulper of Transurban, a principal member of the Fluor team.

Fluor will pay the entire cost of the I-95 project in exchange for toll revenue. The company said it could open the lanes by 2007 and complete them by 2010.

Moving the I-95/395 project forward further expands a rapidly growing list of area roads that may include express toll lanes.

The state received several proposals to add express toll lanes to the Dulles Toll Road last week, two days after Virginia Gov. Mark R. Warner (D) and Maryland Gov. Robert L. Ehrlich Jr. (R) announced plans to study adding express lanes to parts of the Beltway and I-270. Maryland is also exploring adding the lanes to the rest of the Beltway and to roads in the Baltimore area.

Those proposals have moved along without considerable opposition, but the I-95 project has raised several concerns from commuters because it would convert existing lanes to a different purpose.

The lanes are now open to all drivers except during weekday rush hours, when they are limited to carpoolers, and many drivers object to the idea of paying to use the lanes at all times. They also say this will lead even more drivers to crowd into the regular lanes.

Opposition has also come from "slugs," the tens of thousands of carpoolers along the I-95 corridor who stand in line to form spontaneous carpools. Slugs are afraid that a fee-based highway would end their practice, because drivers might rather pay to use the lanes than pick them up. If that happens, the net result would be more cars on the road.

"I think it's going to significantly damage slugging, because right now, the only way to get into HOV lanes is to carpool," said Corey A. Stewart (R-Occoquan), who is a member of the Prince William Board of County Supervisors. "Now people will be able to get into HOV lanes themselves."

Carpoolers also are skeptical of promises that they will always be allowed to ride free. Similar promises were made concerning a toll road in California, but carpoolers now are charged a reduced fee during peak hours.