As US rail, transit, airline and port workers dug through debris, dealt with power outages and assessed damage from massive storm Sandy, it was increasingly clear that restoring full transportation would take some time .

The storm flooded tracks and roads, felled trees and downed power lines. It could be days or weeks before travelers and cargo are moving again normally, officials said.

The three major New York area airports, which serve the nation's busiest airspace, remained closed on Tuesday, but officials later said two of the three -- John F. Kennedy International Airport and Newark Liberty International Airport -- would reopen on Wednesday with limited service.

However, they still had no estimate for a full restoration of service. The Port Authority of New York and New Jersey said LaGuardia Airport remained closed. Between them, the three airports handle 300,000 passengers a day.

Nearly 19,000 flights have been canceled since Sunday, 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 Metropolitan Washington Airports Authority spokeswoman Kimberly Gibbs.

JetBlue spokeswoman Allison Steinberg said the carrier planned to resume operations at New York area airports on Wednesday afternoon.

Even with JFK and Newark resuming limited services, travel itineraries will likely be tangled throughout the week as airlines get staff, planes and passengers into position.

"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.

Necessary repairs

Most Amtrak service along the busy Northeast corridor remained suspended for a second day Tuesday, but officials were working to reopen some services Wednesday.

"We have crews out there right now assessing and making necessary repairs," said Amtrak spokeswoman Christina Leeds.

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.

No deliveries were being made in Washington, D.C., Baltimore and Philadelphia. Government officials only want emergency responders out in such areas, as well Delaware, New Jersey, and parts of Maryland and Virginia, a UPS spokeswoman said.

FedEx Corp said it was working to resume service in affected areas on Wednesday, 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 spokesman Scott Fiedler.

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, before service could resume.

"We are focused on reopening as quickly as possible. But we will not compromise safety," said Port Authority spokesman Pasquale DiFulco. "We need to walk the runways and make sure there's no debris."

He declined to estimate when they would reopen, saying "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.

New York Mayor Michael Bloomberg said it could take four or five days to restore service on the largest U.S. transit system.

"The availability of public transportation will also play into the New York plan, too -- so it remains very, very fluid," said JetBlue spokeswoman Steinberg.

Stranded

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 given 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 doing everything we can to keep people comfortable."

Flights resumed Tuesday at Stewart International Airport, about 60 miles (95 km) 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 were also 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, that it had found flooding, downed trees and power outages, and that teams were removing trees, reinstalling crossing gates and ensuring generators were running to guard against power outages.

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 hardest hit financially. He said AMR Corp's American Airlines operates 25 percent of JFK flights.

"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 said.

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," spokeswoman Victoria Lupica said.

Germany's Lufthansa has an inbound and outbound flight, and cargo carriers have resumed some flights, she said.

Delta Air Lines said it resumed flights to Philadelphia on Tuesday afternoon.

Atlantic City's airport was closed except for military flights. Spirit Airlines, the main commercial carrier there, may resume some service later on Tuesday, said South Jersey Transportation Authority spokesman Kevin Rehmann. – Reuters