But before either step can be taken, train company officials, their contractors and environmental experts need to determine the best way to get thousands of remaining gallons of chemicals, now in a solid state, out of a damaged tanker.
The situation worsened Friday evening as readings showed higher levels of vinyl chloride in the air and authorities decided to evacuate residents who live near the accident site. The evacuation affected several hundred people - far more than the brief one immediately after the derailment.
National Transportation Safety Board members arrived Friday to start the work of piecing together how the accident happened on the swing-style rail bridge where there was another derailment three years ago. With increased health concerns close to the site, NTSB chairman Deborah Hersman said her investigators would initially focus on reviewing records, interviewing witnesses and other parts of the investigation that can be done away from the accident scene.
Meanwhile, local authorities said the job of lifting tanker cars was so immense that no cranes in the Philadelphia area were strong enough to handle it. One was being floated in by barge from New York Harbor - a full day's journey away - for the job.
While the machinery is big, the operation must be precise to avoid any further ruptures to derailed cars.
The derailment happened at about 7 a.m. Friday in Paulsboro, an industrial town directly across the Delaware River from Philadelphia International Airport. The train - two locomotives, 83 freight cars and a caboose - was making its way from Camden when seven cars derailed. Five of them were on the bridge and two were nearby.
Four of the tankers were filled with vinyl chlorine, a gas used to make the common plastic PVC. One of those cars ruptured, spewing some of the gas into the air.
The gas can make people dizzy or sleepy. Breathing very high levels can cause someone to pass out, and breathing extremely high levels can cause death. Most of the vinyl chloride is gone from the body one day after being breathed in.
More than 70 people who live or work in the area went to an emergency room, but none were found to have life-threatening conditions and most were discharged within hours.
The bridge was rebuilt after it buckled in August 2009 when nine cars carrying coal derailed. Officials blamed bridge misalignment for that accident.
Hersman said Friday that her agency will not rule on a cause during its initial, on-the-ground investigation.
On Friday, 17 NTSB workers were in Paulsboro starting to assess the integrity and history of the bridge, the mechanics of the train and the condition of its crew.
She said the cars would be moved only after they'd been documented.
For the ruptured one, the major concern was dealing with the solidified vinyl chlorine that remained inside. Tom Butts, chief of the Gloucester County Office of Emergency Management, said the chemical could be sprayed with water, which would turn it into gas, and then more water could be used to neutralize it as it dissipates into the air. But Hersman said the method of removing the vinyl chloride was not decided for certain by late Friday night.
Local authorities said residents should remain cautious and heed official announcements in case more of the gas gets into the air during the cleanup.
Assemblyman John Burzichelli, a former mayor of Paulsboro who was acting as the town's spokesman on Friday, said getting the rail fixed and reopened is important for commerce in a stretch of New Jersey with refineries and factories.
"This is heavy rail and this is heavy freight," he said.
As long as the bridge is out, he said, businesses will have to rely on barges and trucks to move goods.