By Robin Rieger

PAULSBORO, N.J. (CBS) – Warning signs of trouble on Conrail’s Jefferson Street Bridge in Paulsboro, prior to the seven-car derailment Friday, are numerous according the NTSB who mentioned Monday 23 trouble tickets or work that needed to be done on the span since December 1st 2011.

“There are nine trouble tickets since October 27,” said Deborah Hersman, NTSB Chairman.

On November 19, Hersman said, “A crew walked the bridge and they noted it was not locked.”

The NTSB says November 29th, after another locking issue, two Conrail supervisors spent two hours making adjustments to fix it.

Four additional trains passed over the bridge. The last one at 11:15 the night before the derailment crossed successfully on a green signal, but the crew heard over the radio ten minutes later – “an enunciation stated bridge failed to operate properly again this is minutes after they had successfully cleared the bridge,” said Hersman.

The derailment the next morning punctured one of four cars carrying toxic vinyl chloride. At 2 Monday morning, crews finished removing what they could of it and put a patch on the rail car. Four hours later elevated levels of vinyl chloride prompted a shelter in place for residents

“There is no indication that the product removal operation contributed to the heightened levels,” said US Coast Guard Captain Kathy Moore.

The coast guard says a large crane from New York that removed the plane that was the “Miracle on the Hudson” will be coming here to assist in the train cars removal after the rest of the vinyl chloride is removed.