To that last note, it is always astounding just how costly subway systems are. I am amazed any of them make it to completion simply because the up front cost is

To that last note, it is always astounding just how costly subway systems are. I am amazed any of them make it to completion simply because the up front cost is so high. But once they are in, the improvement to transport standards in the system is wonderful. for example , in my home town we are currently spending $9-11 billion to make a 9KM - 5 station tunnel link. A big investment but a good long term solution. https://en.wikipedia.org/wiki/Metro_Tunnel https://en.wikipedia.org/wiki/Metro_Tunnel