Re:Elon Musk is boring a tunnel to skirt gridlock
by jcranmer on Thursday February 16, 2017 @11:52AM
(#13661398)
> - Has there been any improvement in boring in the last 50 years? The frequently-repeated statement that it hasn't improved would be quite shocking to me since at the very least I'd expect safety to improve.
New Austrian tunnelling method, although that's on the very edge of 50 years ago. Since then, I imagine there's been incremental improvements that aren't easily understood by people who don't work on TBMs (just like steam locomotives didn't really have any revolutionary technologies after Stephenson's Rocket, even though they clearly improved in the next 100 years).
> What are the maintenance costs of tunnels like as compared to surface roads?
More expensive, I imagine. You have more infrastructure to maintain. In addition to the road surface, you have to inspect and maintain the tunnel lining, ventilation, and drainage systems. Given that two of those are active systems, I doubt there's any real savings over the lesser deterioration from weather.
> What are the big costs in the industry? The article hinted that Musk picked up a boring machine for 90% off $15MM, or $1.5MM, which seems extremely cheap given that even small size tunnels in urban areas can cost more than one -billion- US dollars per mile.
TBMs are usually purpose-built. I suspect Musk's "cheap" boring machine is him picking one up after it's completed its project and no one has any use for it.
> - Is there enough boreable space under our cities that this is doable? I know Musk says he wants to go deep, but even at very deep depths you run into problems of sand, boulders, geography, etc, etc.
Most of the buried stuff in our cities are relatively shallow. After around 10-20 feet of depth, you can basically assume nonexistence of municipal utilities, which means the only obstacles are others trying to avoid such things. The real problem in geometry is trying to maintain egress and ingress capabilities, as well as maintaining maximum grades internally. Don't forget that you'll need emergency access tunnels and ventilation shafts for long tunnels (and, usually, if it's not long, it's not deep).
New Austrian tunnelling method, although that's on the very edge of 50 years ago. Since then, I imagine there's been incremental improvements that aren't easily understood by people who don't work on TBMs (just like steam locomotives didn't really have any revolutionary technologies after Stephenson's Rocket, even though they clearly improved in the next 100 years).
> What are the maintenance costs of tunnels like as compared to surface roads?
More expensive, I imagine. You have more infrastructure to maintain. In addition to the road surface, you have to inspect and maintain the tunnel lining, ventilation, and drainage systems. Given that two of those are active systems, I doubt there's any real savings over the lesser deterioration from weather.
> What are the big costs in the industry? The article hinted that Musk picked up a boring machine for 90% off $15MM, or $1.5MM, which seems extremely cheap given that even small size tunnels in urban areas can cost more than one -billion- US dollars per mile.
TBMs are usually purpose-built. I suspect Musk's "cheap" boring machine is him picking one up after it's completed its project and no one has any use for it.
> - Is there enough boreable space under our cities that this is doable? I know Musk says he wants to go deep, but even at very deep depths you run into problems of sand, boulders, geography, etc, etc.
Most of the buried stuff in our cities are relatively shallow. After around 10-20 feet of depth, you can basically assume nonexistence of municipal utilities, which means the only obstacles are others trying to avoid such things. The real problem in geometry is trying to maintain egress and ingress capabilities, as well as maintaining maximum grades internally. Don't forget that you'll need emergency access tunnels and ventilation shafts for long tunnels (and, usually, if it's not long, it's not deep).