The heavy traffic on the new Dulles Toll Road is a signal that motorists would be willing to pay tolls to finance renovation of the nation's deteriorating highways, a transportation group said Wednesday.

Donald T. Beldock, chairman of Basix Corp., told the House Surface Transportation Subcommittee that tolls could be a politically acceptable alternative to raising the gasoline tax to finance the billions of dollars in repairs needed on interstate highways.

"Toll roads are clearly one of the critically required mechanisms for financing the repair and maintenance of highways, bridges and tunnels," said Beldock.

Basix, which produces toll collecting equipment, formed a group last year called the Transportation Infrastructure Advisory Group, to promote tolls and other methods of financing road work. The two other members of the group are E.F. Hutton & Co. Inc. and Vollmer Associates, a transportation consulting firm that has done extensive analysis of toll roads.

Gerald V. Nielsten, a partner with Vollmer, released yesterday the results of a survey of drivers on the 13-mile Dulles Toll Road, which opened Oct. 2. He said the survey shows that drivers are willing to pay tolls for properly maintained and convenient roads.

The survey, conducted April 18, found that:

* Three out of four said they used the road to save time, and of those 60 percent said that they saved more than 10 minutes.

* 84 percent used the road to commute to work.

* 84 percent used the road five or more days a week.

* The average occupancy per vehicle was 1.6 persons a car.

A majority of the drivers paid 75 cents one way, or 6.5 cents a mile, which would total about $350 a year for regular, weekday commuters.

Greenbaum said he was aware that there was opposition to tolls from the trucking industry, the American Automobile Association and several politicians.

The toll advocacy group plans to use the survey to lobby Congress to drop federal restrictions on states that want to use tolls on interstate roads. Current law requires states to first pay back the federal contribution, normally 90 percent of the original cost of the road, according to Beldock.

Asked if the tolls would be an unfair cost to poor families, Beldock said that a users fee on interstate drivers is fairer than a gasoline tax, imposed on all drivers regardless of whether they use the interstate.