As rail, transit, airline and port workers dug through debris, dealt with power outages and assessed damage on Tuesday, one thing became increasingly clear:
Restoring full transportation could take some time.
Hurricane Sandy's assault on the eastern United States so brutally flooded tracks and roads, felled trees and downed power lines, it could be days or weeks before travelers and cargo are moving around normally again, officials said.
The three major New York area airports, which serve the nation's busiest airspace, remained closed on Tuesday, and officials said they had no estimate for when the airports would fully reopen.
Late Tuesday, Port Authority of New York and New Jersey said it was possible that there would be limited service on Wednesday at John F. Kennedy International Airport. There was no indication that LaGuardia and Newark Liberty would offer service on Wednesday. The three airports handle 300,000 passengers a day.
Nearly 16,000 flights have been canceled since Sunday as a result of the storm, including 7,791 canceled on Monday, 6,047 on Tuesday and 635 so far for Wednesday, according to flight tracking service FlightAware.com.
Airlines said they planned to restart service Tuesday at some East Coast airports, including Boston and Philadelphia. Both Dulles and Reagan National in Washington, D.C., were open during the storm and airlines are starting to bring personnel and planes back; limited operations were expected to begin Tuesday afternoon, said Kimberly Gibbs, a spokeswoman with Metropolitan Washington Airports Authority.
"New York airports are still a question," JetBlue spokeswoman Allison Steinberg said on Tuesday. "We are waiting for condition reports from the Port Authority, but we are ready to deploy our plan to resume operations to JFK, LaGuardia and Newark tomorrow afternoon."
And even if the airports reopen, travelers' itineraries are likely to be tangled throughout the week as airlines sort out getting their people, planes and passengers into position.
"If flights (in the New York area) started to resume as early as tomorrow, it could be four to five days before we start to see schedules get back to normal," said Jeanenne Tornatore, a senior editor with online travel agency Orbitz Worldwide. "I think it will be into the late weekend."
Most Amtrak service along the busy Northeast corridor remained suspended for a second day Tuesday, but officials were working to reopen some service Wednesday.
"We have crews out there right now assessing and making necessary repairs," said Christina Leeds, an Amtrak spokeswoman.
United Parcel Service, the world's largest package delivery company, said it had resumed deliveries to hospitals and clinics in Manhattan and New Jersey where roads are safe.
But delivery remained halted in Washington, D.C., Baltimore and Philadelphia. UPS is "respecting areas where government officials only want emergency responders out in Delaware, New Jersey, Philly and parts of Maryland and Virginia," spokeswoman Susan Rosenberg said.
FedEx Corp said it was working to resume service on Wednesday in affected areas, but that hub airport closures and storm debris would affect service. "If you're at a house blockaded by fallen trees, we won't be able to get to it," said Scott Fiedler, a spokesman.
In New York, workers from the Port Authority and the Federal Aviation Administration are assessing damage at major airports, including power issues, possible damage to structures and other safety checks, the FAA and the Port Authority said.
Airlines needed to bring back planes, which were flown out to avoid the storm, to resume service.
"We are focused on reopening as quickly as possible. But we will not compromise safety," said Pasquale DiFulco, a spokesman for the Port Authority. "We need to walk the runways and make sure there's no debris."
He declined to estimate when they would reopen. "Certainly we would like to within the next few days seek to resume normal operations," he said. "But a lot of things are outside our control."
The reopening of New York's transit system will play a large role in reopening the airports, because many of the workers at security checkpoints, customs and concessions, and baggage handlers and flight crews, rely on public transportation to get to work. "That's going to be a key part of the equation," DiFulco said.
New York Mayor Michael Bloomberg said it could take four or five days to restore service on the city transit system, the nation's largest.
"The availability of public transportation will also play into the New York plan, too - so it remains very, very fluid," said JetBlue spokeswoman Steinberg.
About 220 travelers remain stranded at the airports - 100 at John F. Kennedy and 60 each at Newark Liberty and LaGuardia, DiFulco said. They were provided with cots and at least one food vendor was required to stay open 24 hours at each terminal.
"We hate to see anybody stranded," DiFulco said. "We're providing cots and water and working on food vouchers. We're doing everything we can to keep people comfortable."
Meanwhile, flights resumed Tuesday at Stewart International Airport, about 60 miles north of Manhattan, near Newburgh, New York. The first commercial flight since the storm was expected to arrive around noon Tuesday, DiFulco said.
Railway freight companies also were working to restore service. CSX Corp, the nation's second-largest publicly traded railway company, said its network remains closed from Richmond, Virginia, to Albany, New York, and that it had halted traffic originating on other lines traveling to most points between Boston and Philadelphia.
CSX said it still had a lot of its track to inspect, and that it had found flooding, downed trees and power outages along the route.
"Our engineering teams are out removing trees, making sure generators are up against power outages, and reinstalling crossing gates."
Norfolk Southern Corp said it was waiting for floodwater to subside, was clearing snow in western Virginia and West Virginia, and had a power line across tracks in Cleveland.
Airlines could lose $175 million in revenue from flights canceled because of the storm, said Michael Boyd, an aviation consultant with Boyd Group International in Evergreen, Colorado.
"None of it is life-threatening corporately, but it is significant," he said.
Boyd said Delta Air Lines, JetBlue and United would be among the carriers taking the hardest financial hit. He added that AMR Corp's American Airlines operates 25 percent of the flights at JFK.
"From the airline perspective, closing your major hubs for several days is worth of a lot of revenue," said Carter Leake, an analyst at BB&T Capital Markets in Richmond, Virginia.
Airlines have high fixed costs and the loss of revenue would likely lower profits, he added.
Philadelphia's airport did not close but Monday flights were canceled. "We had no damage to the facility, we had no flooding so we were very fortunate," airport spokeswoman Victoria Lupica said on Tuesday.
Germany's Lufthansa has an inbound and outbound flight, and cargo carriers have resumed some operations, she said.
Delta Air Lines said it resumed flights to Philadelphia on Tuesday afternoon.
Atlantic City's airport was closed except for military flights, but Spirit Airlines, the main commercial carrier there, may resume some service later on Tuesday, said Kevin Rehmann, a spokesman for the South Jersey Transportation Authority.
The area was hard hit as the hurricane came ashore Monday night. "The water is receding but it left behind lots of debris and mud and dirt," he said.
(Additional reporting by Nick Zieminksi and Emily Stephenson; Writing by Alwyn Scott; Editing by Phil Berlowitz)