The summer of hell is almost upon us: Amtrak is due to begin its repairs to the aging infrastructure at Penn Station in the coming weeks.

The good news is that by the end of the six-week long period of repairs, service will (hopefully) be improved to the point where derailments and massive delays will (again, hopefully) be a thing of the past; the bad news, of course, is that there will be major service disruptions on Long Island Rail Road, New Jersey Transit, and Amtrak itself.

So what’s the deal with what’s happening at Penn Station? Read on to find out how we got here, who’s to blame, and what is being done to mitigate the issues—including, inevitably, service disruptions.

The current problems

Amtrak’s aging infrastructure has been a problem for some time, but things came to a head earlier this year, when two trains (an Acela on Mach 24, and a NJ Transit train on April 5) derailed near Penn Station. While no one was seriously injured in either accident, they brought to light the major flaws underground; the more than 40-year-old tracks, coupled with a huge increase in riders over the years, have put a tremendous strain on the station’s infrastructure. (It didn’t help that Amtrak admitted that they knew about the problem that set off the April derailment, but didn’t take it all that seriously.)

“The simple fact of the matter is that some of the track and infrastructure in service today at Penn Station was built in the 1970s at a time when we were handling half the trains and a third of the customers that we do today,” Amtrak CEO Charles Moorman said in a statement earlier this year. While the station already had a plan to fix those tracks in place, it would have taken several years; and as Moorman noted in the same statement, “We can’t wait that long. This work needs to be done now.”

How Penn Station got so bad

How much time do you have? Let’s start with the obvious: the tracks are old. The infrastructure is old. Wear and tear happen, and the train station—originally built to accommodate about 200,000 commuters per day—now sees three times that number. And Hurricane Sandy didn’t help, either: salt water flooded the tunnels between New York and New Jersey, causing even more damage.

Who owns what at Penn Station? Amtrak owns and operates the terminal itself, along with the tracks, with the MTA (which operates Long Island Rail Road) and New Jersey Transit (which is controlled by the state of New Jersey) leasing the tracks they use from the national rail agency.

But there are other factors at play, and perhaps the biggest one is the Gateway Program, a $20 billion project to replace the Hudson River tunnel currently used by Amtrak and New Jersey Transit. An earlier version of the project, known as Access to the Region’s Core (ARC), would have been completed next year; however, New Jersey governor Chris Christie axed the project in 2010, after construction had already begun, citing its high costs. (He later used $3 billion from Port Authority that was earmarked for the tunnel to fix roads and bridges in New Jersey.)

So now, we have the Gateway Program: It was announced in 2011, with myriad state and federal agencies, along with Amtrak, as part of the process. But now, federal funding is an issue: The Trump administration has stated its commitment to investing in infrastructure projects, including Gateway, but budget cuts could derail its progress.

And then there’s East Side Access, one of the MTA’s ongoing capital construction projects, which should eventually alleviate some of the strain on Penn Station by adding a new LIRR terminal below Grand Central Terminal. But, as with many MTA projects, it’s been subject to delays and cost overruns. Major construction began in 2007, but a decade on, work is still plugging along.

The new LIRR terminal, which will have eight tracks and (allegedly) serve more than 160,000 commuters, is expected to open at the end of 2022—two years after the ambitious revamp of Penn Station itself is due to be completed.

How it’ll get fixed

Amtrak’s plan will have several different components, though the most important of those is obviously the fixes to the tracks beneath the Hudson River. We’ll let Amtrak do some of the nitty-gritty explaining:

The work during this summer period will occur in “A Interlocking,” which serves as the critical sorting mechanism routing incoming and outgoing trains that enter and exit Penn Station from the Hudson River tunnel and the LIRR’s West Side Yard to the various station tracks and platforms. The work in A Interlocking includes total track and switch replacement.

Six tracks will see closures as a result of this work, leading to changes in service (though, crucially, no actual suspension of service during this time). This is all expected to be done by the end of summer, though there’s more work to be completed in 2018.

In addition to the track work, Amtrak has also commissioned a review of the “interaction, coordination and collaboration” among Penn Station’s various concourses (to be headed up by former MTA chief Tom Prendergast), and the establishment of an operations center that can serve all of the transit systems that use the transit hub.

How it will affect commuters

If you’re a regular Amtrak, Long Island Rail Road, or NJ Transit rider, prepare to have your commute messed with somehow. Repairs will begin July 10 and last through September 1; here’s what that means for you:

Amtrak will see changes on its Northeast Regional and Keystone service, with some trains between New York City and Washington, D.C. being cancelled for the duration of repairs.

will see changes on its Northeast Regional and Keystone service, with some trains between New York City and Washington, D.C. being cancelled for the duration of repairs. Some Long Island Rail Road trains, both to and from Penn Station, have been canceled to help facilitate repairs; in response, the MTA will roll out a “multi-pronged mitigation plan” that includes adding bus and ferry service, allowing for free out-of-station transfers to the subway, longer trains, and even fare discounts. (Those using LIRR bus service, which will leave from designated park-and-ride locations, will be treated to “free Taste NY food and beverage, on-site customer service, free reading materials, phone charging and Wi-Fi stations.” Must be nice.)

trains, both to and from Penn Station, have been canceled to help facilitate repairs; in response, the MTA will roll out a “multi-pronged mitigation plan” that includes adding bus and ferry service, allowing for free out-of-station transfers to the subway, longer trains, and even fare discounts. (Those using LIRR bus service, which will leave from designated park-and-ride locations, will be treated to “free Taste NY food and beverage, on-site customer service, free reading materials, phone charging and Wi-Fi stations.” Must be nice.) Many NJ Transit lines will also be affected, with service on the Morris and Essex lines seeing the biggest disruptions. There will be fare discounts in place for customers riding those lines, and like the LIRR, NJT will cross-honor transfers to the PATH and some New Jersey ferries. Additional NJT bus and ferry service will be put in place as well.

Who’s paying for the repairs and the contingency plans?

That’s the million-dollar question. Amtrak has said that repairs could cost as much as $40 million “in wages, materials and other expenses.” New York and New Jersey legislators, including Governor Cuomo, don’t want commuters to foot the bill for their states’ respective contingency plans; they’ve hinted that they will either seek reimbursement from, or simply not pay Amtrak.

Unsurprisingly, Amtrak isn’t too happy about that; a letter from CEO Moorman to the MTA’s board noted that they have “no basis to seek compensation for such costs” from Amtrak, and to do so would be a “clear violation” of the agencies’ agreements. And as Gothamist reported, some of the MTA’s board members agree, and have suggested seeking federal funding to help alleviate costs. (Who knows how that will go, though; see the Gateway Project, above.)

Will it affect the subway?

In short: not really. While there’s a chance that commuters will be using the subway more during the period in which Penn track work is happening, it’s unlikely to have too much of a ripple effect. (It’s not like you can take the subway to Long Island, for instance.)

Cuomo recently announced an “aggressive action plan” aimed at addressing the problems facing Penn Station, and used that as an opportunity to announce what the MTA is calling its “Design Genius Challenge,” the goal of which is “to reimagine the solutions to the systemic challenges with the system.” This, too, does not really relate to Penn Station.