Integrated light rail/subways that are well designed and well run are pretty much the best mass transport solution we've come up with. The tricky part is the w

Integrated light rail/subways that are well designed and well run are pretty much the best mass transport solution we've come up with. The tricky part is the well designed and well run part and as you alluded to they run into a lot of real world issues during construction. They also really need to be state run at break-even or even subsidized since the benefit is the general increase in economic productivity across the whole region rather than an opportunity to make a lot of money. So politically they don't really fly in the US.