If this technology truly can reduce the cost of tunnel boring by a factor of ten, subway systems can be created in many more cities and existing systems updated

If this technology truly can reduce the cost of tunnel boring by a factor of ten, subway systems can be created in many more cities and existing systems updated with a thicker network. I also wonder if, because of the smaller diameter of the tunnels, a network of self-driving buses doesn't make more sense to deploy in these tunnel networks.