A wrong-side signal problem was eliminated, leaving human error as the only possible cause.

There's no indication there was a signal problem, but all signals are being checked in that location.

Insert jacks themselves can be the source of intermittent signal problems.

One train was delayed 23 minutes because of signal problems in Mineola, she said.

This has been known as the phantom signal problem.

But such technology would probably be costly and, in the New York area, it could encounter signal problems.

During this period, the tower was moved closer to Columbia, but the signal problems remained.

But signal problems occur if he rotates the antenna even slightly.

False activations are the most common signal problem, officials say.

In the more than 400 accidents in the Times analysis, 30 percent of the signal problems were listed as confirmed.