There's a reasonable limit on how high you can build, as well as noise concerns and NIMBY. Building over existing neighborhood is a nogo. Train transfers are

There's a reasonable limit on how high you can build, as well as noise concerns and NIMBY. Building over existing neighborhood is a nogo. Train transfers are a pain in the ass. I live a block away from a rail station and only use it when going to the absolute heart of downtown. Even then I drive as close as I reasonably can and take the train for the last 3 miles. It saves me at least an hour round trip vs taking the train the whole way.