I'm of the opinion that every 500k+ city should have a subway line.
I grew up in a city with one (just one for the majority of my 20 years there) and if there's one thing I miss from that place it's the ability to move at an average speed of 35km/h at any time the trains were operating, especially at 2am on a Friday night after a couple of beers with the guys.
The other thing I noticed when I was visiting my family there during the recent holidays is that there are so few cars in places close to the subway lines - roughly half the usual concentration. The incentive to have one is just not strong enough.
I grew up in a city with one (just one for the majority of my 20 years there) and if there's one thing I miss from that place it's the ability to move at an average speed of 35km/h at any time the trains were operating, especially at 2am on a Friday night after a couple of beers with the guys.
The other thing I noticed when I was visiting my family there during the recent holidays is that there are so few cars in places close to the subway lines - roughly half the usual concentration. The incentive to have one is just not strong enough.