What to Know Amtrak says there's no estimate as to when the tracks affected by the NJ Transit derailment Monday will be operating again

Sources told News 4 that Amtrak hopes to have service back to normal by Friday; crews have been working around the clock to repair damages

With eight of the 21 tracks at Penn Station out of commission, NJ Transit, Amtrak and LIRR riders have been dealing with rough commutes

A switch machine was so badly damaged in Monday's derailment in Penn Station that eight of the 21 train tracks at the station will be out of commission for a couple more days at least — unwelcome news for commuters who have crammed crowded trains and platforms during ongoing rail delays and cancellations.

The New Jersey Transit train derailment has left eight of 21 tracks inoperable at the station, according to Amtrak COO Scot Naparstek. Naparstek wouldn't estimate Tuesday when service might return to normal, but transit sources told News 4 New York the agency is aiming to have service back by Friday morning.

In a press release, Amtrak said modified service would stay in place through Thursday. Delayed and canceled trains have already wreaked havoc for hundreds of thousands of travelers and commuters in the tri-state and beyond since the derailment Monday morning.

Crowds of frustrated commuters are expected to gather at NJ Transit stations as switch issues continue to plague nearly half of Penn Station tracks. Ida Siegal reports.

Earlier on Tuesday, NJ Transit Executive Director Steve Santoro said it's unclear when full service on the commuter rail will resume. Crews are working around the clock to repair the damage from the derailment, officials say. Here's your guide to navigating Tuesday's commute.

"Clearly we have sympathy for the riders that are enduring this," said Santoro, who told News 4 he rides the North Jersey Coast Line and understands the frustration. "This is not something we are enjoying in any way, shape or form."

Naparstek said, "We apologize for any inconvenience we have caused anyone. It sincerely is not our desire."

The MTA's Long Island Rail Road, which also runs on the Amtrak-owned tracks at Penn Station, has also been suffering from the derailment. The railroad had already canceled 10 trains going into Manhattan Wednesday morning and said it was terminating others in Queens. Spokeswoman Beth DeFalco says the agency is trying to prepare customers for "days of delays."

Asked what the best case scenario would look like, DeFalco said, "You'd have to ask Amtrak because they're doing the timing, but they've told us days."

In Photos: Commuter Chaos After Derailment, Flooding

Not all eight tracks are damaged but the tunnels can only be accessed by certain tracks, and there are power collection differences between LIRR, Amtrak and NJ Transit that limit the tracks that each train can use, according to an Amtrak spokesman.

Investigators are still looking into why the NJ Transit train derailed just outside the station Monday morning. It was the second derailment at the busy Manhattan hub in 11 days: the first involved an Amtrak Acela. Naparstek says he believes the two derailments aren't related.

Neither Amtrak nor NJ Transit have offered any explanation for Monday's derailment. Three cars in the middle of an inbound NJ Transit train dislodged from a track as it approached a platform at Penn Station.

A NJ Transit train derailed in Penn Station, causing a big mess for commuters at Penn Station. The accident injured five people and now an investigation is underway into what went wrong. Erica Byfield reports.

No serious injuries were reported in either derailment, but the track shutdowns caused havoc on NJ Transit and the Long Island Rail Road, and all up and down Amtrak's Northeast Corridor between Washington, D.C., and Boston.

Combined with flooding problems Tuesday, the morning commute turned into an abject nightmare.

The Northeast Corridor and North Jersey Coast lines on NJ Transit were still operating on a holiday schedule, mucking up the commute for the estimated 100,000 people who ride into New York each weekday. More details here.

Throngs of commuters desperate for alternatives faced challenges finding them, with the PATH experiencing a brief suspension on the Hoboken-33rd Street line, delays on other lines and the crush of people causing crowding-related problems throughout the New York City subway system.

Police controlling the number of people going in and out of #Hoboken #PathTrains. Expect to never leave NJ. @NJtransit pic.twitter.com/GcZXQhW4QH — Jennifer Rosenthal (@jenn_rosenthal) April 4, 2017

Confused crowds trying to figure out service changes packed the Hoboken PATH station, according to one commuter named Carlos. There were no announcements or updates, he said. NJ Transit trains were bypassing Secaucus and dumping passengers into the Hoboken terminal as crowding worsened. Bus and ferry lines surged as people sought alternative means of getting into Manhattan.

"I don't know how everybody does it every day," passenger Dina Lundy said. "I could never. It would not be an option to have a job in New York."

PATH says the Hoboken-to-33rd Street line was running with delays Tuesday evening, and the 33rd Street-to-Hoboken line was running via the World Trade Center line, with delays.

Long Island Rail Road riders dealt with their own nightmare of a morning commute Tuesday, and not just because of delays from the derailment. There was an additional broken rail near Queens Village, a disabled NJ Transit train in one of the East River tunnels and signal trouble near Central Islip. Also, there was a passenger in need of medical assistance at Mineola.

LIRR said Tuesday afternoon it was back on schedule, but there were still evening rush-hour cancellations and delays because of the shortage of tracks: 18 trains would be canceled and eight would be diverted, LIRR said. Here's your guide to navigating Tuesday's commute.

Mass transit riders, including thousands of Mets fans who flocked to Citi Field for opening day, are dealing with a nightmarish evening commute after the second derailment at New York’s Penn Station in 11 days. Ida Siegal reports.

"It's fair to say that the conditions at Penn affects everybody," said MTA acting chair Fernando Ferrer, addressing LIRR riders. "Even though Amtrak owns it, we all dwell in that same place and travel into the same tracks. When something bad happens like this, it affects everybody."

The two derailments at Penn Station renewed calls for accelerating progress on an ambitious, $20 billion-plus project, known as Gateway, to add a new rail tunnel under the Hudson River and expand Penn Station. The current tunnel is more than 100 years old and operates at capacity during peak commuting hours.

The cost of the tunnel, estimated at roughly $10 billion, is to be split between New York, New Jersey and the federal government, but supporters fear President Donald Trump's budget released last month could jeopardize the federal slice of the project by proposing to pay only for projects that have advanced to the final contract stage.

John Porcari, a former deputy U.S. secretary of transportation who is the interim head of the development corporation overseeing Gateway, said Tuesday that a new tunnel wouldn't have stopped the two recent derailments from happening. It would, he said, lessen the aftershock to commuters because the eight tracks currently out of service would have been able to connect to the new tunnel.

"It would have been a minor blip instead of a major nightmare for commuters," he said.