BALTIMORE -- CSX Transportation Corp. will begin limited drug testing of employes under an agreement with two unions that aims to avoid mandatory random drug tests for workers in safety-related jobs.

"This is as far opposite of random testing as we are going to get in this industry," said John McCown, spokesman for the Brotherhood of Locomotive Engineers.

The engineers' union and the United Transportation Union signed the agreement recently with the railroad company. Union members said they hope similar agreements could be negotiated with Conrail and Amtrak.

Sixteen people were killed and more than 170 injured in a Jan. 4 collision of an Amtrak and a Conrail train near Baltimore. Traces of marijuana were found in the blood and urine of both the Conrail engineer and brakeman.

The accident prompted calls for drug tests for employes in the airline, railroad trucking and bus industries. Legislation to that effect has been passed by a Senate committee and is awaiting further congressional action.

Passage of a law or a federal rule requiring random drug testing would automatically nullify the CSX agreement with the two unions. But union officials said they hoped that a successful limited testing program would convince Congress that random testing was unnecessary.

Random tests "take 95 percent of the people that are innocent and ask them to prove they are innocent through a very humiliating process," said union spokesman McCown.

The CSX pact, affecting 17,000 transportation industry workers, is the first such agreement in the industry, officials said.

The affected workers include engineers, brakemen, firemen, conductors and yardmasters -- jobs considered critical to safety. New employes in those job classifications are already required by federal regulation to undergo drug testing.

With the new agreement, CSX employes who are members of the unions will be tested only if they are injured on the job seriously enough to require a report to federal authorities or are involved in an accident resulting in $5,200 or more in damage.

Testing will also be required if appearance, behavior or speech create a "reasonable suspicion" that the employe has been using drugs or alcohol.

Workers will be tested after returning from layoffs or resuming work after 90 or more days off.

By agreeing on specific circumstances for testing, the unions say they are effectively eliminating random tests.

Amtrak spokesman Clifford Black said the company supports random testing, although it is waiting for federal action before conducting such tests. A spokeswoman for Conrail declined comment