Comment by djsumdog

That's a lot of good insight into tunnel boring. Thanks for that.

I know Cincinnati's subway failed because of some bad tunnelling that caused foundations to sink .. well that and the great depression. If they had started earlier or designed it better, Cincinnati could have a Chicago like transit system today. Unfortunately it took them years to get a tram and there are people still trying to shut that down instead of expand it! Unbelievable.

I know in Seattle, many of the tunnels (like to Northgate/UDistrict) have actually been fully bored. The new stations are still not due to open for a few years, mostly because the majority of time isn't spend on the tunnels, but installing track, electrics and building the underground rail stations.