Less than a week after a tragic train wreck in Graniteville, a federal agency urged railroad companies Tuesday to tighten safety procedures involving switches or face tougher government regulation.

The Federal Railroad Administration said companies should make sure their rules require train crews who handle hand-operated switches to advise a dispatcher after they restore track switches to their normal position.

The agency also said a train’s conductor and engineer should sign a form saying they know in what position they left the switch. Switches divert a train from main tracks to side tracks.

Federal investigators suspect that a switch left in the wrong position caused Thursday’s Norfolk Southern crash, in which a 42-car freight train ran down a side track and smashed into a locomotive parked at a textile mill.

Nine people died from chlorine inhalation after one of the tanker cars split open in the nation’s worst railroad chemical accident since 1978.

“An improperly lined switch invites disaster and can be easily avoided,” Robert Jamison, the FRA’s acting chief, said in a statement.

The agency said the Graniteville wreck and the same type of wreck two days later in Bieber, Calif., prompted concern about switch safety. In the California case, a freight train was diverted onto an industrial track and struck two rail cars, injuring two railroad employees and causing nearly $1 million in damage.

FRA data show there were 23 train accidents caused by improperly aligned switches during the first nine months of 2004.

Tuesday’s safety advisory focuses on sections of railroad track that do not have signals warning trains of impending danger ahead, such as a misaligned switch. Several experts interviewed this week by The State said Thursday’s crash could have been avoided if a signal system had been in place. They said that although the engineer braked, he apparently did not have enough time to stop the train once he realized there was a problem.

Railroad administration spokesman Warren Flatau said the safety advisory does not have the force of law, but companies face regulation from the agency if they do not take measures recommended.

“Absolutely,” he said. “As we check their level of compliance, that will aid in determining if additional and specific” regulations should be imposed.

Spokesmen for South Carolina’s two major railroads, Norfolk Southern and CSX, said their corporations would check to make sure their procedures are sound and implement any new rules they deem necessary.

“We are reviewing our current regulations and comparing them to the new information from the FRA,” Norfolk Southern spokesman Frank Brown said. “We will take the appropriate actions swiftly.”

U.S. Sen. Jim DeMint, R-S.C., and U.S. Rep. Gresham Barrett, R-S.C., are expected in Graniteville today.

DeMint spokesman Wesley Denton said the senator hopes train companies will comply with the advisory and avoid tougher regulations.

Reach Fretwell at (803) 771-8537 or sfretwell@thestate.com. The Associated Press contributed to this report.