At over a century old and over maximum capacity, The New York subway system is in desperate need of an upgrade. Each weekday, over 5 million riders enter train cars built to withstand approximately 70,000 daily riders, and rely on them to safely and swiftly reach their destination. While MTA-related issues seem to pile up with each passing year, renovations require a great deal of both money and time, not to mention the patience of anxious commuters.

So how does the MTA keep operating trains and tracks safe and functional when it comes time to repair others? It’s a complicated story that has to do with money, population growth and aging infrastructure, among other factors.

Here’s what you need to know about how the MTA plans and executes their major renovations, how long they might take, and what to expect for the future of the NYC subway.

The MTA is still fixing and fortifying, years after Sandy.

To understand how the MTA works, it makes sense to look at its past and ongoing projects. When Hurricane Sandy slammed the east coast in 2012, much of the city was spared — but the subways have ceased to be the same. The ensuing “Fix & Fortify” campaign by the MTA is still ongoing. It’s next focus will be on repairing the L train, a highly trafficked cross-borough line.

This project won’t begin until 2019, but when it does, managing the commute to or from the Williamsburg and Bushwick areas won’t be easy. The MTA predicts either a complete 18-month shutdown or three years of limited service in order to repair the line’s Canarsie tube, which was severely compromised by flooding.

Sandy repairs are typically accomplished on weekends and nights to minimally impact highly-congested workday commutes. Tunnels like the Clark, Rutgers and Cranberry tubes are among those subjected to weekend repairs, to the inconvenience of F, 2 and 3 train riders.

Record numbers of riders mean more repairs and more delays.

Even before Sandy, the MTA’s struggles were real — and challenging enough that the MTA has been compared to Sisyphus in his quest to roll a boulder uphill. Increased crowding and aging infrastructure means more repairs and more funding is necessary just to keep up with average wear and tear. The prospect of future hurricanes only ramp up the gravity of the situation.

Unfortunately, the MTA isn’t in any position to accomplish these fixes immediately. This is in part thanks to record ridership, which has risen to nearly 6 million people a day up from about 4 million in the 1990s. This crowding, in turn, has lead to a swelling delays, which have quadrupled since 2012 to about 20,000 a year.

Thanks to debt and budget constraint, the MTA is in financial straits.

Another obstacle preventing the MTA from immediately acting on repairs is their delicate financial situation. The city and the state split the cost of the MTA’s budget, the rest of which is made up by riders’ fare prices, but Albany has not been eager to help fund the agency. Only when the MTA uses up its resources from the prior round of funding will the state’s contribution be “anticipated” rather than “mandated,” meaning necessary funding could be delayed even further.

Next, let’s not forget the MTA’s massive debt of $34 billion, which is greater than 30 of the world’s countries combined. In the 1980s, the MTA began borrowing from banks to fund luxury projects; now, raised rider-fares are paying back the extravagant ideas of the past. This model is especially unsustainable considering revenues are rising 1.5 percent each year, while costs rise 5.5 percent, according to NY Mag.

It could take 50 years to fix all subway’s issues.

Between debt, hurricanes, and overcrowding, the MTA certainly has its work cut out. And while crucial repairs will need to be made, some say we’re likely to be half a century before we see it all completed. That’s according to the Citizens Budget Commissions, which estimates that stairs, platforms and pillars in 280 of New York City’s 668 stations won’t be fully fixed until 2067.

52 years is two-thirds the human lifespan — far too long to wait for necessary updates to keep riders safe and the subway running smoothly. Still, gradual repairs are certainly better than none at all.

The MTA is still prioritizing tech and expansion projects.

Repairs are necessary on the day-to-day, but above all, the MTA has the future in mind. While it’s easy for daily riders to assume the MTA should focus solely on repairs, it’s critical to think ahead. As the city’s population flourishes and ridership grows, expansion will be needed just to free up space and stop the strain on current lines.

“At a time when growing ridership is leading to crowding and delays, we must pursue expansion projects,” MTA spokesman Kevin Ortiz told the NY Daily News.

Recent expansion projects have been less than fruitful so far, with projects like the Second Avenue expansion delayed indefinably.

Technology projects are moving along much better, with all underground stations set to be fully equipped with WiFi by 2017. Subways will soon begin accepting contactless payments, too, and new countdown clocks and subway cars will also be added gradually. The clocks we can expect on lettered lines in 2018, and the cars we may see replacing the old C, J and Z trains by 2022.

Creative solutions for consideration

With public services that New York’s residents and economy rely on, cutting costs and downsizing in a fashion similar to a business would only make matters worst. Revenue and a large labor force is vital to completing projects, but continuing to raise fare prices is not exactly fair to cash-strapped commuters.

The Daily Dot has suggested that the MTA could benefit from an ultra-useful train-tracking app with a one-time fee for users, as well as WiFi and solar panels for diversified revenue streams. NY Mag suggests cutting bloated administrative costs, privatizing buses, selling and leasing MTA-owned real estate, and raising toll prices for drivers. The Move NY plan in particular would collect  $1.35 billion a year in revenue from bridge tolls, congestion pricing, and taxi surcharges.

It’s a complicated situation, and no solution will come without losses of its own. But in order for the subway to keep running at the quality and speed at which we need it, we need the MTA to keep its head dry amidst a storm of gnarly obstacles.