Why are so many metros underground? Isn't that more expensive than an elevated?

Building a metro underground is sometimes cheaper than building it above ground, just like how digging a tunnel might be easier than building a bridge.

Metros are like buses, but for cities. They carry lots of people quickly, and they work best when they’re not blocked by cars or buildings. That’s why many metros go underground, to avoid the busy streets above.

When you build a metro above ground, it needs space for tracks and stations. That means tearing down houses or moving people away, which can be expensive, like when you clean out your room before you move to a new house.

But if you go underground, you can use the space already there, kind of like playing in the basement instead of building a new room on top of your house. You might need to dig, but digging is often cheaper than moving everything around.

Going underground lets trains zoom through the city without waiting for traffic lights or cars. That means fewer delays and happier passengers, just like how you can run across the playground instead of walking past all the kids.