Minitube

Digging tunnels is obviously more expensive when your tube diameter is larger. The idea is to shrink the tube diameter to a mere 3ft. How will people travel? Lying down, of course! The train comes into the station (the largest part of the system), it is composed of a series of pods 2ft10inches wide and 7 ft long. As the train comes in, the pods all orient themselves via a system of hydraulic arms so that the length becomes the depth (they are now 7ft high instead of 7ft long). Half the pod slides away, giving just enough room inside for an adult to stan comfortably. Passengers exit the train, then others get onboard in a standing position. The doors close, the pods re-orient themselvces so everyone is lying on their backs (Note: You have to get in the right way, otherwise you'll be lying face down). Then the train stars off again. Not only is the tunnel cost greatly reduced, but because each pod can turn individually the turning radius can be much greater. All trips are in private, tubes can leave the ground and go right into office buildings or go alongside elevated railways if necessary.