PHILADELPHIA, JAN. 30 -- The control tower operator who fled his post after Friday morning's wreck of Amtrak's Night Owl apparently realized he had put the train on a collision course moments before it slammed into a maintenance vehicle, investigators said today.

"He said 'My God, I put him on Track No. 2,' or words to that effect," said National Transportation Safety Board member Joseph T. Nall at a briefing here tonight.

The employee, Tom Connor, disappeared after the Washington-to-Boston overnight train, carrying 160 passengers, struck maintenance equipment at nearly 90 miles per hour, injuring 25. Officials said the train was not diverted to a clear track, as it should have been, while maintenance work was performed on the track it normally takes.

Nall said Amtrak employees interviewed today said they observed Connor "pace nervously, gather up his personal belongings and leave" soon after the collision.

"{Connor's} attorney said he would arrange for a meeting Monday afternoon, but he didn't specify a time or place," said John Jacobsen, an Amtrak spokesman. "He said he'd call us back. He is a big missing link."

Nall said he seeks to question Connor before his memory fades. Investigators also said it would be almost futile, so many days after the crash, to determine whether Connor had been using illegal drugs or alcohol. Alcohol levels in a test so long after the incident would show almost nothing, although traces of some drugs might be detected. Other Amtrak employees involved in the accident were tested for drug and alcohol use.

Nall said other employees in the tower "didn't see anything unusual about Connor's behavior relating to drugs or alcohol."

The accident occurred early Friday morning in Chester, about 15 miles south of here. Trains in the Northeast Corridor, Amtrak's busiest line, were running up to 25 minutes late today because only one track near the accident site was in service, as railroad crews worked to repair the three tracks torn up by the collision. Two tracks were reopened later today, an Amtrak spokesman said.

Track 2, on which the 10-car train struck a 17-ton piece of maintenance machinery, is not expected to be back in service until next week because a bridge was heavily damaged, Amtrak officials said.

Rails on three tracks were bent and hundreds of railroad ties were plowed up when the train, traveling at 87-to-90 miles per hour, struck a ballast regulator, used to level and spread gravel in the track's road bed. Amtrak officials estimated the damage to the tracks and structures at $300,000.

Investigators from Amtrak and the safety board have determined that the force of the collision pushed the ballast regulator about half a mile past the first of two bridges. The ballast regulator caught the abutment of the second bridge, throwing the train off the track, officials said. The engine flipped 180 degrees. The ballast regulator smashed through the engine cab, and as it tumbled down the embankment, the engineer, Mark Kenny, 36, was thrown through the windshield.

Kenny, of Brick Township, N.J., and a passenger, Robert Davis, 43, of Queens, N.Y., were hospitalized overnight. Twenty-three others aboard were treated for minor injuries and released.

Jed Dodd, general chairman of the Pennsylvania Federation of the Brotherhood of Maintenance of Way Employees, which represents the maintenance workers, said tonight his union has long argued that derailments such as Friday's could be prevented if maintenance machinery were equipped with devices that would activate signals. That could have warned the engineer of the Night Owl the track was occupied.

But Clifford Black, an Amtrak spokesman, said reliable technology has not been developed for the lighter-weight and smaller maintenance equipment.

The Night Owl left Washington at 10:20 p.m. Thursday and was scheduled to arrive in Philadelphia at 12:43 a.m.

Shortly after 10 p.m., a 14-mile section of Track 2 around Chester was put out of service by a maintenance foreman. A safety clip was attached to switches inside the control tower to assure that the switches were not inadvertently moved, Amtrak officials said. Sometime later, officials said, it was removed.

"Somebody had to have taken the device off," Jacobsen said. "That's why we want to talk to Connor. What is the explanation?"