The day before a train carrying toxic chemicals derailed on a swing bridge in Paulsboro, the crew of another train reported the span across the Mantua Creek had not closed properly when they attempted to use it, federal crash investigators reported this afternoon.

They also disclosed that there is no record of an inspection of the bridge's mechanical parts that was supposed to take place in September.

National Transportation Safety Board Chairwoman Deborah Hersman said a train crew preparing to cross the bridge about 3:15 a.m. Thursday — about 27 hours before the derailment — reported that they found the bridge "four inches shy of being closed."

The bridge, owned and operated by Conrail, is open to recreational boat traffic from March 1 through Dec. 1 and train crews must punch in a radio code to close it and obtain a green signal to advance during those months.

The crew of that train punched in the code several times before the bridge closed and they received a green light.

Two Conrail supervisors later that morning spent two hours inspecting the bridge and making adjustments "so it would work properly," Hersman said.

Four other trains crossed the bridge without incident that day. The last crew, however, reportedafter crossing the bridge around 11:15 p.m. that they received an audible notice over the radio from the bridge's automated open-close system that the bridge "failed to operate properly," indicating it remained closed and had not opened as it was supposed to.

The crew of the train that derailed the next morning found the bridge closed, but with a red signal light.

After the conductor walked the bridge and found nothing visibly awry, the engineer punched in the code three times in a failed attempt to get a green signal, Hersman said.

Following standard Conrail procedure, they radioed the Conrail control center in Camden and obtained permission to operate againt the signal.

It was about 7 a.m. Friday and only the two locomotives and few freight cars made it across the bridge when seven cars derailed and four tanker cars ended up in the creek,

Hersman said even if the bridge is closed, the signal will not change to green unless four "side locks" are "fully locked."

The latest developments followed a morning during which the residents of Paulsboro who have not been evacuated were told to "shelter in place" — close their windows and stay indoors — for the second time since the derailment after officials said they had detected higher levels of vinyl chloride than with which they were comfortable.

The order was lifted about 4 1/2 hours later, ars. Work crews trying to transfer the chemical from a derailed tanker stopped work.

Originally, officials had ordered that all residents stay inside their homes. That order was lifted about 11 a.m. But all public schools in the area will remain closed until further notice.

Officials had already extended an evacuation of the immediate area through Saturday. Dozens of people reported breathing difficulties immediately after the derailment, but the injuries were not considered serious.

Kathy Moore, a captain with the U.S. Coast Guard, the lead agency handling the cleanup at the site, said this morning officials noticed a rise in the level of vinyl chloride fumes about 6 a.m. this morning. However, she said the level was, "100 times" less than the threshold posing a serious danger. Nevertheless, officials were concerned enough that they took action. They were not clear why the level was rising.

The higher levels came after crews were trying to transfer the chemical from one of the rail cars. Already, she said, levels were dropping, but that officials were acting out of precaution. A temporary patch was put on one of the rail cars.

"The threshold for action is very, very low," Moore said.

A freight train derailed Friday in Paulsboro as it crossed tracks leading over a bridge over Mantua Creek that had collapsed as recently as 2009. The derailment caused a tanker of vinyl chloride to spill into the waterway and 12 residential blocks were evacuated. day, which means members of 48 households in the evacuation zone won't be able to get home for the rest of the week.

Conrail, owner of the tracks on which the 82-car train derailed, is providing hotel rooms and vouchers for everything from laundry to restaurants, officials said Sunday. But displaced residents expressed frustration, some saying they had spent the weekend in a state of uncertainty and simply wanted to return home. Some said they were running out of money despite Conrail's promises to reimburse their expenses.

The crew was crossing the bridge Friday morning at 7 m.p.h. - the speed limit is 10 m.p.h. - when the emergency brakes activated, NTSB representatives said. They looked back to see the bridge collapsing behind them. Removing the tankers from the creek is tricky, officials said. Crash debris in the water must be removed before crews can begin working on the cars.