The New York City subway system is one of the most iconic in the world, servicing over five million people every weekday. But its also been mired in budget problems, and some parts of its technology have remained largely unchanged since its inception in 1904.
The combination of these two things makes working on the subway quite the task for the Metropolitan Transportation Authority (MTA). And the MTA’s Instagram does a good job of showing what it’s like, taking you behind the scenes of flooded tunnels, snowy tracks, and welding jobs.
Here are 24 photos that show what it takes to keep one of the world’s biggest subway systems running:
Additional reporting by Graham Rapier.