Sen. James Exon chided the Department of Transportation for underestimating the severity of heavy-truck access problems and suggested he may press ahead with corrective legislation.

The Nebraska Democrat, chairman of the Senate Commerce Committee's Surface Transportation Subcommittee, said he was seriously concerned that a handful of states were denying highway access to big trucks against congressional wishes.We can't have, under the guise of states rights, one or two states thumbing their noses at the intent of Congress, he said at a hearing exploring the truck access issue.

The trucking industry and some shippers have been complaining for years that eight Eastern states unfairly restrict the movement of 48-foot-long single trailers and twin-trailer combinations within their borders.

A 1982 law opened virtually all interstate highways to these bigger rigs. Many states also made thousands off miles of state roads available to longer trucks.

States also were instructed to provide reasonable access for trucks traveling to and from the designated highways. But some states have limited access sharply, forcing truck lines to use smaller trailers or travel circuitous routes.

The Transportation Department is expected soon to propose rules that would define reasonable access and terminal as a way of resolving the problem.

Sen. Exon also introduced legislation last year to broaden heavy-truck highway access. But he has said the bill was intended only to further debate and had not been pressing for its passage.

After hearing from several trucking companies and shippers at Thursday's hearing, Sen. Exon said he may reconsider his position and press for approval of his bill this year.

Earlier, he criticized the DOT for its slow handling of access disputes.

I think the problem is more complicated and has been delayed much longer . . . than you believe to be the case, he told Richard P. Landis, the associate administrator for motor carriers at the DOT, who was testifying before the committee.

Mr. Landis had acknowledged that access is a difficult and controversial issue, but added, The problems are limited . . . The solution is at hand.

Sen. Exon disputed that assessment.

If I felt the solutions were at hand, I wouldn't have called this hearing, he said.

Sen. Exon said heavy-truck access should have received more attention from DOT officials.

He compared the department's actions to the Interstate Commerce

Commission's handling of railroad regulatory issues. Sen. Exon said the ICC was failing to respond as the Congress directed in rail disputes.

He said the administration's implementation of the 1982 highway access law was the key issue, adding, I don't think things are working as well as they should in this area.

Mr. Landis said the department's proposal addressing highway access problems would be unveiled shortly.

Kevin Heanue, an aide to Mr. Landis, said many states and some highway safety groups had been urging the department to leave access decisions in the states' hands.

But Mr. Heanue added, The decision to move ahead (with the DOT access proposal) is based on the conclusion that there is a need for more uniformity and that pre-emption (of state authority) is needed to achieve it.

Thomas Donohue, president of American Trucking Associations, said his industry was making some progress in negotiating access solutions in some states, especially Pennsylvania.

But he blasted the DOT for not moving faster to publish its access proposal.