The railroad and trucking industries seldom see eye to eye, but they're united in opposing congressional proposals to place restrictions on the interstate transportation of waste.

Both industries also are vigorously opposing moves to classify used locomotive and truck oil as hazardous waste, an action that could cost them millions in disposal costs and increased liability.Those are just two of the many contentious issues Congress is wrestling with as it sits down to a job it may not complete this year, reauthorization of the Resource Conservation and Recovery Act. It is the major federal statute dealing with all aspects of waste generation, classification and disposal.

As space in the nation's remaining landfills has become scarcer, municipal solid waste often is shipped many miles before it is dumped. The practice has caused a public uproar in states that are net importers of solid waste. Frequently thwarted by the courts, those states have turned to Congress to enact regulations restricting or banning out-of-state waste.

Railroads stand to lose if Congress passes new laws restricting interstate waste movements because they are beginning to view the long-haul transportation of municipal solid waste as an emerging source of business.

David Tittsworth, director of the Environmental Transportation Association, which represents railroads and waste companies, said it would prefer no new transport restrictions, but it supports a compromise bill introduced by Rep. Rick Boucher, D-Va.

The bill would give local governments the authority to determine whether waste disposal facilities within their jurisdictions should be permitted to import out-of-state waste.

Richard F. Goodstein, a vice president of government affairs for Browning Ferris Inc., a giant waste hauling and disposal firm in Houston, also supported the Boucher bill's approach.

The American Trucking Associations estimates the trucking industry generates about 300 million gallons of used oil each year.

The Environmental Protection Agency and most states now consider such used oil and used oil filters a non-hazardous waste. That designation keeps disposal costs down and allows fleets to recycle their waste oil or burn it.

In a letter last week to Rep. Al Swift, chairman of the Energy and Commerce Committee's subcommittee on transportation and hazardous materials, Edwin L. Harper, president of the Association of American Railroads, said, "EPA's data on used locomotive crankcase oil specifically show that there is no basis for designating such oil as a hazardous waste."

Allen Schaeffer, ATA's director of environmental affairs, said trucking companies were also concerned about the possibility of increased state taxes on motor oil to subsidize used oil collection programs.

Other areas of concern for the trucking industry include:

* Scrap tires. The industry wants to prevent a national tire tax and wants Congress to provide incentives and grants to new technologies for tire disposal and use.

* Batteries. The industry sees no need for a federal recycling program. ATA says 37 states currently have battery exchange or trade-in programs in place.