Yet another idea that came to my mind when I was sitting on the toilet

We should be able to build underpasses. Let's say we have a wide street/avenue with a high level of traffic, and we have bus/tram stops on both sides of the street - it would somehow make it easier for passengers to get to the right bus/tram/whatever mean of transportation if we built an underpass

And that way we could also connect other things, like maybe a metro platform to another platform, or a street, etc. - there are plenty of possibilities