Updated

Investigators are looking more closely at a stretch of track near the site of a deadly commuter train crash after finding abnormalities Wednesday in equipment that senses trains and transmits speed commands.

Equipment along a 740-foot stretch of track failed to recognize a device that simulates the presence of a train during the tests, said Debbie Hersman of the National Transportation Safety Board, which is leading the investigation into the crash that killed nine people. Five other stretches of track, or circuits, near the Maryland state line showed no problems.

"Whether trains are operated in automatic or manual, these circuits are vital," she said. "We're particularly interested in the speed commands that might be sent from that circuit when there's a train standing on that circuit."

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Hersman wouldn't elaborate on what she called "anomalies" found in the circuit, saying more tests were needed. Investigators planned to test the track with a six-car train Wednesday night.

The deadliest accident in Metrorail's 33-year history occurred Monday when a train plowed into another train that was stopped. The moving train was controlled primarily by computer at the time of the crash, but there is evidence the operator tried to slow it down.

Hersman said Wednesday that inspectors found 300 to 400 feet of markings on the rails, indicating some emergency braking took place before the crash. Hersman also has said the emergency brake control on the moving train was found pushed down, though it's not clear how or when that happened. The operator of the oncoming train was among the dead.

Hersman said investigators hoped to interview the operator of the other train on Thursday, a day after his release from the hospital.

NTSB officials say their investigations can take more than a year.

The cars destroyed in Monday's crash included some of the oldest in Metro's fleet. Federal officials wanted them phased out because of their tendency to compact in a crash, but Metro officials said the agency has lacked the money for replacements.

A union representing Metro transit workers also demanded changes in safety procedures. Jackie Jeter, the union's president, said cars from the aging series involved in the crash should be placed in the middle of trains, rather than at the front or back because they are less stable.

The union also asked that operators be allowed to choose whether to use automatic mode, which is typically employed during rush hour. Jeter demanded that Metro officials not mandate speeds at which trains should travel, saying operators were being pushed to move too fast.

Metro spokesman Steven Taubenkibel said the agency was looking into the union's demands.

The union isn't the only one to raise concerns about running trains in automatic mode.

In Chicago's 'L' train system, operators never use an automatic system, said Robert Kelly, president of the city's transit workers union.

"If it were left to me, I would never have a train operate in automatic mode or autopilot," said Kelly, a former train operator.

"The problem with this job is complacency," he said, noting the risk of problems increases when operators aren't forced to stay alert.

Robert Jones, who retired from Metro after 18 years as a train operator and then came back in 2007 to work part-time, disagreed.

Operators have to keep an eye on hundreds of people at each train station platform during rush hours and prepare to stop for any safety concerns. They also open and close the doors, which requires them to look back from a window to make sure no one gets caught in the doors.

"You have to be aware all of the time," Jones said. "It's a job that requires your full attention."

Metro has said it needs $12 billion over the next 10 years to maintain services and replace aging equipment such as the older railcars. The agency has long argued the federal government should contribute because its trains serve the capital, and many riders are federal workers.

Last year, Congress approved $1.5 billion in funds over 10 years, but with a condition that the District of Columbia, Maryland and Virginia match the amount. Now that all three jurisdictions served by Metro have agreed, Congress can move forward, officials said.

The region's congressional delegation introduced a measure Wednesday that would finalize plans to provide the funds.

"The safety of our citizens is our highest priority," said House Majority Leader Steny Hoyer, who represents Maryland.

Even with an infusion of cash to order new cars, Metro officials caution that it would still take about five years to get the equipment.

"It's not an off the shelf product," Metro spokeswoman Lisa Farbstein said. "It's something that's custom made."

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