7 ms·

Ok, so one thing I've noticed reading the 120 comments in this thread and the article is that literally nobody knows anything about boring, or tunnels. Musk kno

Ok, so one thing I've noticed reading the 120 comments in this thread and the article is that literally nobody knows anything about boring, or tunnels. Musk knows nothing, he put someone in charge who knows nothing, the reporter knows nothing, and the commenters here even admit they are completely guessing and know nothing about boring/tunnels. I definitely don't know anything about tunnels. It's a joke that came to life, and it's a pretty funny one, and I'm fairly confident Musk can make improvements, but I'd still like to know something about the whole process. I assume someone here knows something about this, or at least can find out, so here's my wishlist: - 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. - What are the maintenance costs of tunnels like as compared to surface roads? - 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. - 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.

sschueller 10y ago
There has been a lot of improvements in boring. [1] [2] [1] http://www.lexpose.ch/2013/02/gotthard-base-tunnel-inside-swiss-innovation/ http://www.lexpose.ch/2013/02/gotthard-base-tunnel-inside-sw... [2] https://www.herrenknecht.com/en/products/core-products/tunnelling/gripper-tbm.html https://www.herrenknecht.com/en/products/core-products/tunne...
owenversteeg 10y ago
Answering my own question, bit by bit: It looks like there have in fact been improvements in tunnel creation in the last 50 years. Examples: - NYC Third Water Tunnel, under construction since 1970. 24 deaths, the vast majority of which were decades ago as safety improved. In fact, the first tunnels were blasted and drilled; the newer ones are made with a boring machine. - St. Gotthard Road Tunnel, 1969-1980, just one lane in each direction and 2 deaths per mile. A comparable transportation tunnel today in the area is the Gotthard Base Tunnel, 0.2 deaths per mile. - Older tunnels apparently caused thousands of workers to die due to silica exposure. It also seems that tunnels are more dangerous than roads per mile by many orders of magnitude. For example, the aforementioned Gotthard Road Tunnel had over 875 accidents and 30 deaths in a span of just 24 years.
- knz 10y ago
  > For example, the aforementioned Gotthard Road Tunnel had over 875 accidents and 30 deaths in a span of just 24 years. Pollution from congestion probably has at least a similar impact in terms of premature death and debilitating disease. Edit. Down votes for stating that pollution from congestion causes premature death and serious health effects - yikes! Is that even a disputed fact? Google is full of academic papers on the very subject. The first result I see talks about congestion pricing having a massive impact in London. I would argue that congestion relief from the construction of tunnels would have a similar impact. http://oem.bmj.com/content/65/9/620.short http://oem.bmj.com/content/65/9/620.short - "Predicted benefits... were 183 years of life per 100 000 population... In London overall, 1888 years of life were gained."
- battlebot 10y ago
  Don't forget that boondoggle in Boston!
HUSSTECH 10y ago
I can speak somewhat for the UK, but I assume the same can be said for most of Continental Europe, Japan and China where (deep) underground tunnels for have been around for a long time. The deeper tunnels of the London Underground are "bored", that is a full circular profile is cut for the tunnel path. This is contrasted with the "cut and cover" method, which just digs a pit, builds a support structure, and covers it back up [1]. Cut an cover is not feasible for deeper tunnels, too much structure is required to hold up the weight of earth above you. Some of the older lines on the underground were dug this way; fun fact: You'll notice in NYC or Boston for example, that the subway stations are all square in their tunnel shape profile, and you can visibly see the support structures, that's because they are mostly not very deep, and used the cut and cover method. I'd be interested to know if any US cities have deeper tunnels? (Despite not being very deep, cut and cover is a very good way to quickly build mass transport for growing cities.) The BBC has been doing programmes on the Underground for years, so there has been a steady steam of documentaries on this topic! I apologise if you can't get to any of these links: - A 1969 BBC documentary on the Victoria line (hopefully answers your question 1)^: http://www.bbc.co.uk/programmes/p00sc29t http://www.bbc.co.uk/programmes/p00sc29t - A 2014 documentary on Crossrail, London's latest new underground line^^: http://www.bbc.co.uk/programmes/b04bwkj1 http://www.bbc.co.uk/programmes/b04bwkj1 ^currently streaming in the UK ^^ looks like this one is no longer available, except on Amazon. The Crossrail project website has some info on the show [2], and in general the Crossrail site tires to put educational info on there for the curious [3] [1] https://en.wikipedia.org/wiki/Tunnel#Cut-and-cover https://en.wikipedia.org/wiki/Tunnel#Cut-and-cover [2] http://www.crossrail.co.uk/news/crossrail-documentary-the-fifteen-billion-pound-railway/ http://www.crossrail.co.uk/news/crossrail-documentary-the-fi... [3] http://www.crossrail.co.uk/construction/tunnelling/meet-our-giant-tunnelling-machines/ http://www.crossrail.co.uk/construction/tunnelling/meet-our-...
- Nav_Panel 10y ago
  > I'd be interested to know if any US cities have deeper tunnels Some NYC subway stations and lines were built with boring as opposed to cut and cover. 90% of the new 2nd Avenue line, for example, is planned to be bored[1]. Here[2] is an article with more details about the tunnel boring machine used -- the comments also have a lot of good discussion. Also, Los Angeles has done some boring for its new subway lines[3]. 1: https://en.wikipedia.org/wiki/Second_Avenue_Subway#Construction_methods https://en.wikipedia.org/wiki/Second_Avenue_Subway#Construct... 2: http://secondavenuesagas.com/2010/05/14/down-the-rabbit-hole-a-tunnel-boring-machine-comes-alive/ http://secondavenuesagas.com/2010/05/14/down-the-rabbit-hole... 3: https://www.metro.net/projects/tunnel-boring-machine-tbm/ https://www.metro.net/projects/tunnel-boring-machine-tbm/
WorldMaker 10y ago
« 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. » Certainly out here in a much more karst [1] part of the country (I'm in Kentucky specifically) there's just about no way, from what I read, to bore under our cities without threatening the geologic stability of just about everything above it, because our cities are already essentially built "on top" of caves, caverns, and limestone hollows. Sinkholes are a real problem with sometimes deadly effects. Tunnels in general here can be very expensive to cover survey costs and insurance. I am not a civil engineer, but I would assume there are probably maintenance tasks and costs that differ for this sort of geology. [1] https://en.wikipedia.org/wiki/Karst https://en.wikipedia.org/wiki/Karst
- zardo 10y ago
  If you're already on top of caverns, the tunnels might actually be able to stabilize and reinforce the ground. In theory... the actual digging would undoubtedly be complicated by caverns.
  - WorldMaker 10y ago
    It is just unfortunate that the caverns naturally created by water erosion so rarely correspond to interesting or useful transportation corridors. :)
cossatot 10y ago
There are two main problems with increasing depth: Rocks and water. Rocks are the biggest. The ratio of rock to finer sediment increases with depth until bedrock is reached. This might be anywhere from 1 to 1000 meters depth but in most cities it's probably <30 meters average (less in hilly parts of town, more in river valleys etc). Bedrock can be bored through and is quite strong, but it's slow and may be more expensive (although it could cut down on regulatory and post-boring structural reinforcement costs quite a bit). Mixed soft sediment and large boulders are often trickier to deal with--the boring rate can vary wildly, and it's difficult ta maintain the proper rate balance between cutting and sediment removal. Remove too slow and things clog, remove too fast and the pressure becomes too low and voids can develop, which are then filled in by overlying sediment as the ground above collapses a bit. Shallow seismic techniques could certainly be used for imaging/boulder detection some number of meters in front of the borer if it was built in right. But I don't know how useful it would be. Can they steer or reroute? Probably not much... Water is a lesser concern but is still important. The water table is pretty shallow (<10 m almost everywhere) and tunnels need to be sealed. This is pretty straightforward, but I really wonder about LA during an earthquake with a deep transit tunnel (especially in winter when the water table is higher). What if a long tunnel's walls are seriously breached? Could it flood and drown passengers who may be blocked by debris etc?
jcranmer 10y ago
> - 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).
- rst 10y ago
  The Bloomberg article confirms he bought a used TBM, probably for not a whole lot more than scrap.
ChuckMcM 10y ago
I'm not surprised that people who design boring machines or design tunnels are not regular readers or commentators here on HN :-). Like Musk, I've felt that tunneling is under utilized (unfortunately I don't have the resources he has to bring to bear on it) but there is a wealth of information out there on the current state of tunneling. Three interesting projects that have a number of 'explainers' and various papers out there are the Channel Tunnel (the 'Chunnel'), the Gotthard Base tunnel in Switzerland, and the Seattle Alaskan Way Viaduct. These three provide a useful survey level of understanding of the elements of building tunnels, the challenges to be met, and to some extent what is possible today. Seattle is particularly instructive with regard to the impact on existing buildings vs depth and the challenges of fixing a tunneler mid-bore as it were. The Chunnel provides some great experience on depth and the ability to withstand pressure, and the Gotthard tunnel went through everything from sand to bedrock and speaks well to the ways of mitigating different materials. Taking the time to read the material on those three projects can certainly make you feel like you understand some of the issues. Musk is correct in that there are a lot of things that are "well known" now by various engineering firms. For example producing pre-stressed wall sections so that a boring machine can leave behind tunnel instead of an unfinished hole. The process of supplying material and removing it, the build as you go narrow gauge rail lines for moving the tunneler and the material, and mitigation factors for different kinds of material (from rock to sand). There are practical considerations that aren't technological. For example you need ventilation. And that means a vent shaft to the surface periodically, and that means negotiating with people above the tunnel for access for that. Getting in and out of the tunnel is also its own challenge. If you want to let people drive their own cars in a tunnel you need a way to get in and get out, if you put a bus or a train in the tunnel you need stations where people can board. Those kinds of things, which involve negotiation with people who might not share, and might even resent, your vision seems to be the "hard" problem to the idea.
- abduhl 10y ago
  I design both boring machines and tunnels and am a regular reader on HN. I have worked on tunnels ranging from the smallest to the largest, rock to soil, and all forms of construction. I have stopped commenting on any tunnel related Elon topic due to people refusing to believe my experience and expertise when it does not align with what Elon Musk and his team of "experts" have said or published in their desk studies.
mschuster91 10y ago
> Musk knows nothing, he put someone in charge who knows nothing, the reporter knows nothing, and the commenters here even admit they are completely guessing and know nothing about boring/tunnels. Musk didn't know much about rockets, electric cars and batteries but still managed to found and run the first private rocketry company, the first mass-market electric car and is responsible for the creation of the world's biggest battery factory. Not to mention Hyperloop, but there's no real product yet. What Musk touches that eventually becomes gold, I believe - especially because his name and fame attracts talent that is willing to work extremely intense for his goals.

sschueller 10y ago

There has been a lot of improvements in boring. [1] [2] [1] http://www.lexpose.ch/2013/02/gotthard-base-tunnel-inside-swiss-innovation/ http://www.lexpose.ch/2013/02/gotthard-base-tunnel-inside-sw... [2] https://www.herrenknecht.com/en/products/core-products/tunnelling/gripper-tbm.html https://www.herrenknecht.com/en/products/core-products/tunne...

owenversteeg 10y ago

Answering my own question, bit by bit: It looks like there have in fact been improvements in tunnel creation in the last 50 years. Examples: - NYC Third Water Tunnel, under construction since 1970. 24 deaths, the vast majority of which were decades ago as safety improved. In fact, the first tunnels were blasted and drilled; the newer ones are made with a boring machine. - St. Gotthard Road Tunnel, 1969-1980, just one lane in each direction and 2 deaths per mile. A comparable transportation tunnel today in the area is the Gotthard Base Tunnel, 0.2 deaths per mile. - Older tunnels apparently caused thousands of workers to die due to silica exposure. It also seems that tunnels are more dangerous than roads per mile by many orders of magnitude. For example, the aforementioned Gotthard Road Tunnel had over 875 accidents and 30 deaths in a span of just 24 years.

knz 10y ago
> For example, the aforementioned Gotthard Road Tunnel had over 875 accidents and 30 deaths in a span of just 24 years. Pollution from congestion probably has at least a similar impact in terms of premature death and debilitating disease. Edit. Down votes for stating that pollution from congestion causes premature death and serious health effects - yikes! Is that even a disputed fact? Google is full of academic papers on the very subject. The first result I see talks about congestion pricing having a massive impact in London. I would argue that congestion relief from the construction of tunnels would have a similar impact. http://oem.bmj.com/content/65/9/620.short http://oem.bmj.com/content/65/9/620.short - "Predicted benefits... were 183 years of life per 100 000 population... In London overall, 1888 years of life were gained."
battlebot 10y ago
Don't forget that boondoggle in Boston!

HUSSTECH 10y ago

I can speak somewhat for the UK, but I assume the same can be said for most of Continental Europe, Japan and China where (deep) underground tunnels for have been around for a long time. The deeper tunnels of the London Underground are "bored", that is a full circular profile is cut for the tunnel path. This is contrasted with the "cut and cover" method, which just digs a pit, builds a support structure, and covers it back up [1]. Cut an cover is not feasible for deeper tunnels, too much structure is required to hold up the weight of earth above you. Some of the older lines on the underground were dug this way; fun fact: You'll notice in NYC or Boston for example, that the subway stations are all square in their tunnel shape profile, and you can visibly see the support structures, that's because they are mostly not very deep, and used the cut and cover method. I'd be interested to know if any US cities have deeper tunnels? (Despite not being very deep, cut and cover is a very good way to quickly build mass transport for growing cities.) The BBC has been doing programmes on the Underground for years, so there has been a steady steam of documentaries on this topic! I apologise if you can't get to any of these links: - A 1969 BBC documentary on the Victoria line (hopefully answers your question 1)^: http://www.bbc.co.uk/programmes/p00sc29t http://www.bbc.co.uk/programmes/p00sc29t - A 2014 documentary on Crossrail, London's latest new underground line^^: http://www.bbc.co.uk/programmes/b04bwkj1 http://www.bbc.co.uk/programmes/b04bwkj1 ^currently streaming in the UK ^^ looks like this one is no longer available, except on Amazon. The Crossrail project website has some info on the show [2], and in general the Crossrail site tires to put educational info on there for the curious [3] [1] https://en.wikipedia.org/wiki/Tunnel#Cut-and-cover https://en.wikipedia.org/wiki/Tunnel#Cut-and-cover [2] http://www.crossrail.co.uk/news/crossrail-documentary-the-fifteen-billion-pound-railway/ http://www.crossrail.co.uk/news/crossrail-documentary-the-fi... [3] http://www.crossrail.co.uk/construction/tunnelling/meet-our-giant-tunnelling-machines/ http://www.crossrail.co.uk/construction/tunnelling/meet-our-...

Nav_Panel 10y ago
> I'd be interested to know if any US cities have deeper tunnels Some NYC subway stations and lines were built with boring as opposed to cut and cover. 90% of the new 2nd Avenue line, for example, is planned to be bored[1]. Here[2] is an article with more details about the tunnel boring machine used -- the comments also have a lot of good discussion. Also, Los Angeles has done some boring for its new subway lines[3]. 1: https://en.wikipedia.org/wiki/Second_Avenue_Subway#Construction_methods https://en.wikipedia.org/wiki/Second_Avenue_Subway#Construct... 2: http://secondavenuesagas.com/2010/05/14/down-the-rabbit-hole-a-tunnel-boring-machine-comes-alive/ http://secondavenuesagas.com/2010/05/14/down-the-rabbit-hole... 3: https://www.metro.net/projects/tunnel-boring-machine-tbm/ https://www.metro.net/projects/tunnel-boring-machine-tbm/

WorldMaker 10y ago

« 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. » Certainly out here in a much more karst [1] part of the country (I'm in Kentucky specifically) there's just about no way, from what I read, to bore under our cities without threatening the geologic stability of just about everything above it, because our cities are already essentially built "on top" of caves, caverns, and limestone hollows. Sinkholes are a real problem with sometimes deadly effects. Tunnels in general here can be very expensive to cover survey costs and insurance. I am not a civil engineer, but I would assume there are probably maintenance tasks and costs that differ for this sort of geology. [1] https://en.wikipedia.org/wiki/Karst https://en.wikipedia.org/wiki/Karst

zardo 10y ago
If you're already on top of caverns, the tunnels might actually be able to stabilize and reinforce the ground. In theory... the actual digging would undoubtedly be complicated by caverns.
- WorldMaker 10y ago
  It is just unfortunate that the caverns naturally created by water erosion so rarely correspond to interesting or useful transportation corridors. :)

cossatot 10y ago

There are two main problems with increasing depth: Rocks and water. Rocks are the biggest. The ratio of rock to finer sediment increases with depth until bedrock is reached. This might be anywhere from 1 to 1000 meters depth but in most cities it's probably <30 meters average (less in hilly parts of town, more in river valleys etc). Bedrock can be bored through and is quite strong, but it's slow and may be more expensive (although it could cut down on regulatory and post-boring structural reinforcement costs quite a bit). Mixed soft sediment and large boulders are often trickier to deal with--the boring rate can vary wildly, and it's difficult ta maintain the proper rate balance between cutting and sediment removal. Remove too slow and things clog, remove too fast and the pressure becomes too low and voids can develop, which are then filled in by overlying sediment as the ground above collapses a bit. Shallow seismic techniques could certainly be used for imaging/boulder detection some number of meters in front of the borer if it was built in right. But I don't know how useful it would be. Can they steer or reroute? Probably not much... Water is a lesser concern but is still important. The water table is pretty shallow (<10 m almost everywhere) and tunnels need to be sealed. This is pretty straightforward, but I really wonder about LA during an earthquake with a deep transit tunnel (especially in winter when the water table is higher). What if a long tunnel's walls are seriously breached? Could it flood and drown passengers who may be blocked by debris etc?

jcranmer 10y ago

> - 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).

rst 10y ago
The Bloomberg article confirms he bought a used TBM, probably for not a whole lot more than scrap.

ChuckMcM 10y ago

I'm not surprised that people who design boring machines or design tunnels are not regular readers or commentators here on HN :-). Like Musk, I've felt that tunneling is under utilized (unfortunately I don't have the resources he has to bring to bear on it) but there is a wealth of information out there on the current state of tunneling. Three interesting projects that have a number of 'explainers' and various papers out there are the Channel Tunnel (the 'Chunnel'), the Gotthard Base tunnel in Switzerland, and the Seattle Alaskan Way Viaduct. These three provide a useful survey level of understanding of the elements of building tunnels, the challenges to be met, and to some extent what is possible today. Seattle is particularly instructive with regard to the impact on existing buildings vs depth and the challenges of fixing a tunneler mid-bore as it were. The Chunnel provides some great experience on depth and the ability to withstand pressure, and the Gotthard tunnel went through everything from sand to bedrock and speaks well to the ways of mitigating different materials. Taking the time to read the material on those three projects can certainly make you feel like you understand some of the issues. Musk is correct in that there are a lot of things that are "well known" now by various engineering firms. For example producing pre-stressed wall sections so that a boring machine can leave behind tunnel instead of an unfinished hole. The process of supplying material and removing it, the build as you go narrow gauge rail lines for moving the tunneler and the material, and mitigation factors for different kinds of material (from rock to sand). There are practical considerations that aren't technological. For example you need ventilation. And that means a vent shaft to the surface periodically, and that means negotiating with people above the tunnel for access for that. Getting in and out of the tunnel is also its own challenge. If you want to let people drive their own cars in a tunnel you need a way to get in and get out, if you put a bus or a train in the tunnel you need stations where people can board. Those kinds of things, which involve negotiation with people who might not share, and might even resent, your vision seems to be the "hard" problem to the idea.

abduhl 10y ago
I design both boring machines and tunnels and am a regular reader on HN. I have worked on tunnels ranging from the smallest to the largest, rock to soil, and all forms of construction. I have stopped commenting on any tunnel related Elon topic due to people refusing to believe my experience and expertise when it does not align with what Elon Musk and his team of "experts" have said or published in their desk studies.

mschuster91 10y ago

> Musk knows nothing, he put someone in charge who knows nothing, the reporter knows nothing, and the commenters here even admit they are completely guessing and know nothing about boring/tunnels. Musk didn't know much about rockets, electric cars and batteries but still managed to found and run the first private rocketry company, the first mass-market electric car and is responsible for the creation of the world's biggest battery factory. Not to mention Hyperloop, but there's no real product yet. What Musk touches that eventually becomes gold, I believe - especially because his name and fame attracts talent that is willing to work extremely intense for his goals.