More expensive than rails? There may be good arguments against this system, but this is not one of them. Unless you are talking about building a railroad in the

More expensive than rails? There may be good arguments against this system, but this is not one of them. Unless you are talking about building a railroad in the desert the cost of pushing a pipe in the ground (which can even be done without opening up the street for a small diameter) is certainly much lower than acquiring right of way alone, not to mention building all the support infrastructure such as bridges, etc.