Is digging down really cheaper than going up?
Chicago has got an elevated train [0] and even double decker streets [1] and those don't have lots of the problems that tunnels do like ventilation, escape tunnels, and moving all the dirt.
Chicago has got an elevated train [0] and even double decker streets [1] and those don't have lots of the problems that tunnels do like ventilation, escape tunnels, and moving all the dirt.