A Conrail official said Saturday that the Paulsboro railroad bridge damaged during a derailment Nov. 30 will be replaced rather than repaired.

Spokesman Michael C. Hotra said Conrail would design and construct a new movable bridge over the Mantua Creek in Paulsboro.

The decision was made because the current bridge is in a locked position, allowing rail traffic to pass above, but not boat traffic beneath.

Under federal regulations, the bridge is to be closed from Dec. 1 to March 1 each year, when it normally reopens to boat traffic. But it can't reopen to boats this year, Hotra said.

"Conrail has submitted a request with the U.S. Coast Guard," he said, "to extend this order and keep the bridge in a fixed position until September 2014, when the new movable bridge is expected to be complete."

Officials decided to act because repairing the draw function on the existing bridge would take the same amount of time as building a new one, he said. There was no other substantive issue driving the decision, he said.

He could not say what the cost difference would be between repairing or replacing the span.

"We have been in touch with slip owners, the local marina, and other boaters impacted by this request," Hotra said.

Federal authorities have inspected the bridge and pronounced it safe for train traffic, he said.

Last year, four tankers derailed and fell into the creek. One ruptured, releasing dangerous vinyl chloride into the air. Many residents, who were displaced from their homes for days, have filed lawsuits against Conrail.

A preliminary review by the National Transportation Safety Board found that the bridge had not been locked properly for rail traffic when the derailment occurred, officials said. It has been in a locked position ever since, Hotra said.

Contact Bonnie L. Cook

at 215-854-2611 or bcook@phillynews.com.