Little or no mention of the back end of the machine. The front end, where cutting takes place, gets all the attention. The segment placing arm got a mention. But most of the length of the machine does other things.
The usual TBM setup has a two-track narrow gauge railroad behind it. Segment cars bring ring segments forward, and muck cars remove the spoil. Track cars bring more railroad track. Tool cars and worker cars are in the mix occasionally. All this is happening on an unfinished railroad, because the back end of the TBM has to lay the track and move cars from one track to the other. All the stuff for this takes up more length than the cutting part. A tunneling project is an entire construction site compressed into a long, narrow hole. So logistics in the tunnel are a big deal.
Now, this is where The Boring Company was expected to innovate. Something involving driverless Tesla chassis, maybe. But they never did. Others have built such systems.[1]
But not The Boring Company.
Just curious, if the rails are such an issue, is it not just cheaper to drive the cars (no need for self driving?) or is paying someone to do it not worth the complexity savings? Or are there other downsides to not having the rail?
Either each car needs a driver or you need something to keep all the trailers precisely lined up. One new system has that; a human drives the "locomotive" and the trailers have automated steering to follow the lead vehicle precisely enough to not bump into traffic in the other direction. This is still experimental.
At the other end of the line, outside the tunnel, there's a whole rail yard. The different kinds of cars have to be sorted out, loaded, and unloaded. So there's a need for a big staging area.
Here's an overview of traditional tracked systems.[1] I've tried to find a video of the back end system and yard, but nobody seems to make such videos. It's too boring.
If the Boring Company mention was an attempt to combat the hype (“everybody is talking about yet another musk company”), you've contributed to the problem in much the same way as the saying regarding traffic: “You're not stuck in traffic, you are traffic.”
> During construction of the Hudson River Tunnel in 1889, 25% of the workers died from decompression sickness.
Less interesting but of far greater value to humanity has been the innovation in heath and safety regulations.
According to this article [1] one worker died per foot of the Hudson River Tunnel.
> In 1906, attitudes toward the sandhogs changed after a series of accidents beneath the East River. Blown-out tunnels put the dangers of the profession on display in a way few New Yorkers could ignore, and the Progressive-Era press worked to publicize them. Suddenly, sandhogs were big news, and people started to complain about their high death rates.
That 25% statistic is unreferenced (or else I'd have to read all the sources to find where he got that from). It's sort of difficult to imagine it being true. Because you'd also have to factor in all the people who got decompression sickness but didn't die of it, but who couldn't work anymore—you'd think that would be even higher. I have to believe that it's to be interpreted as "of the many workers who died during this project, 25% died from decompression". Maybe I'm too skeptical, but that makes more sense to me.
My grandfather was for a short time in the railroad construction business under Japanese leadership about 50 years after the Hudson project. I have never met him, but I can imagine he would be delighted if the death rate would just be 25%.
IIRC for the Indonesian, voluntary workers the death rate was 80%. For the prisoners like my grandfather the rate was lower, simply because they started working later (and perhaps some racism from the leadership).
This was not so much health and safety regulation-related, but simple ignorance. The dangers of rapid decompression were not recognized until early 20-th century when underwater construction became more common.
That's why "decompression sickness" is called "caisson sickness" in several languages.
They did know migrant workers were dying, they thought it was a sickness caught being below ground so they kept them in dorms away from everyone else.
When you are hiring new people each day, to replace the ones who died, knowing that a quarter will lose their life, ignorance around exactly how they died is no excuse.
Today in my country at least a single workers death is not acceptable. Accidents happen but prosecution happens if everything was not done by the book.
I don’t buy it. 25% of workers is a lot of workers for a megaproject of this scale. This would either have to be a single devastating week, in which case they would learn about it really quickly and would probably still be the collective memory, or O'Rourke Engineering Construction Company willfully allowed their workers to die out of mysterious causes and opted not to investigate.
The latter is actually more likely but not really. There is no way the tunnel would have been finished if a quarter of the workforce was dying and the company just allowed it to continue happening.
Compare this to the Panama Canal which started construction under US supervision the same year as the Hudson North River tunnel. They didn’t know much about the spread of tropical deceases but they knew enough to supply their workers with mosquito nets etc. The French effort to build the canal totally failed, primarily because of the high death toll among workers. When the US took over preventing the spread of deceases was a primary concern. And this project now lives in our collective memory as one that costed so many lives.
Now there is no doubt in my mind that working condition for the Hudson North River tunnel were horrendous, and that far too many unnecessary deaths resulted from total disregard of worker safety by the construction company. That this number was 25% and that it was because they didn’t know about decompression sickness... That I don’t buy, dozens of workers dying from the construction company cutting corners, overworking their workers, setting harsh deadlines, not providing safety gears, and (yes) not treating sick workers, that is far more plausible.
I mean, I don't think we really invented safety regulations. I am not sure if a regulation existed that could have allowed the HRT to be built safely with the technology of the time.
I think technology is inherently linked with standard of living which is inherently linked to the value of a life.
Funnily enough, my father is at the 11th international symposium on “Ground Freezing” in London at this very moment. Most of the time you have to freeze the ground before you can drill.
He has been working in specialist civil engineering for many years and builds tunnels all over the world. He has told me many exciting and hard-to-believe stories about tunnel construction and tunnel boring machines.
E.g. during the work on the Eurotunnel. Here the British tunnel boring machine was diverted into the rock near half the length of the tunnel and left there. It was cheaper than somehow taking it out again.
Anyways, since my dad is always very stressed due to his job, I am happy to have gained a foothold in IT and not tunnel boring :D
> E.g. during the work on the Eurotunnel. Here the British tunnel boring machine was diverted into the rock near half the length of the tunnel and left there. It was cheaper than somehow taking it out again.
> E.g. during the work on the Eurotunnel. Here the British tunnel boring machine was diverted into the rock near half the length of the tunnel and left there. It was cheaper than somehow taking it out again.
AFAIK it was not just the cost, but the problem of two TBMs (British and French) meeting head to head. The british were driven out of the way so that the French ones could proceed.
Wow, as someone who follows the construction progress of Los Angeles' Purple Line (the only heavy rail transit line currently in active boring in the US) I did not know how fast that even reaching the speed of a snail would be:
If we assume the tunnels are being bored at somewhere near the average of ~100meters/week, and the snail is about ~1000meters/week, that's a 10x speedup in the time to dig right there!
The total length of the three segments is about 9 miles (~14,500 meters)[1], with the last segment projected to open in 2027. Digging started in Fall of 2018[2]. Los Angeles is using what looks like 6 TBMS, two for each segment, to dig parallel tunnels. Segment one completed digging in January of 2022[3], and as of August 2023 Metro has delayed full completion of segment one to 2025[4], therefore it appears that even though digging is not the end-all-be-all, it does take up >50% of the entirety of the construction timeline (~4 years digging + 3 years other construction for segment 1, including stations, track, electrical, and testing).
Using the article as a guide, then, somehow speeding up the digging by a factor of 10 would mean digging could take as little as 21 weeks or ~5 months months, rather than ~4 years, and reduce the project timeline by 50% from 7 years to 3.5 years!
This would be huge for when Los Angeles eventually begins to bore the heavy rail tunnel under the Sepulveda mountain pass, which would be 14 miles, most of it likely tunneled [5].
Very cool article as someone who has had little to no exposure on this topic.
A very interesting youtube channel [1] I recently came across is Cutting Edge Engineering Australia - they do mostly heavy equipment repair/fab.
Some common tools used are air-arc gougers for clean and rapid removal of material along with mill/lathe machining. Had never really considered the conceptual transfer over to something like tunnel boring (air powered debris and rotational removal) but it seems similar.
Holy cow it's a small world. I just subbed to that channel last week. Love seeing someone so practical and capable and the bloopers at the end are a lot of fun.
The projection for boring company is interesting at least. They seem to argue most of the "wins" are procedural, and relate to business practices, paperwork and general business efficiency, the "we can do 1km a day" claims not withstanding (they don't claim this. But, it is definitely an out-there claim of their speed) -The reality of the equipment and process they use is still an advance on most, but it's more normal pace of improvement not the 10x people like to dream about.
I wish we had the "Thunderbirds" Corkscrew TBM. Michael Moorcock writes about subterranian ground-melting craft too in his multiverse 'Oswald Bastable' series.
It's essentially a long ad for the company that makes the machines, but this video (and some of the others they've put out) are fascinating and describe the whole process of tunnel making (with a very high production value):
What an awesome writeup. Just wanted to add a link to a good website tracking the progress of the Hampton Roads Bridge Tunnel expansion project, something near and dear to me as someone who has suffered much frustration driving through the current one. The three bridge tunnels around HR themselves are pretty cool engineering feats. I found the explainers at this website about the TBM in use quite interesting.
Readit News
The usual TBM setup has a two-track narrow gauge railroad behind it. Segment cars bring ring segments forward, and muck cars remove the spoil. Track cars bring more railroad track. Tool cars and worker cars are in the mix occasionally. All this is happening on an unfinished railroad, because the back end of the TBM has to lay the track and move cars from one track to the other. All the stuff for this takes up more length than the cutting part. A tunneling project is an entire construction site compressed into a long, narrow hole. So logistics in the tunnel are a big deal.
Now, this is where The Boring Company was expected to innovate. Something involving driverless Tesla chassis, maybe. But they never did. Others have built such systems.[1] But not The Boring Company.
[1] https://tunnelingonline.com/mobiletronics-demonstrates-auton...
At the other end of the line, outside the tunnel, there's a whole rail yard. The different kinds of cars have to be sorted out, loaded, and unloaded. So there's a need for a big staging area.
Here's an overview of traditional tracked systems.[1] I've tried to find a video of the back end system and yard, but nobody seems to make such videos. It's too boring.
[1] https://www.robbinstbm.com/products/tunnel-boring-machines/b...
[2]
Less interesting but of far greater value to humanity has been the innovation in heath and safety regulations.
According to this article [1] one worker died per foot of the Hudson River Tunnel.
> In 1906, attitudes toward the sandhogs changed after a series of accidents beneath the East River. Blown-out tunnels put the dangers of the profession on display in a way few New Yorkers could ignore, and the Progressive-Era press worked to publicize them. Suddenly, sandhogs were big news, and people started to complain about their high death rates.
[1] https://daily.jstor.org/the-sandhogs-who-built-the-new-york-...
IIRC for the Indonesian, voluntary workers the death rate was 80%. For the prisoners like my grandfather the rate was lower, simply because they started working later (and perhaps some racism from the leadership).
That's why "decompression sickness" is called "caisson sickness" in several languages.
When you are hiring new people each day, to replace the ones who died, knowing that a quarter will lose their life, ignorance around exactly how they died is no excuse.
Today in my country at least a single workers death is not acceptable. Accidents happen but prosecution happens if everything was not done by the book.
The latter is actually more likely but not really. There is no way the tunnel would have been finished if a quarter of the workforce was dying and the company just allowed it to continue happening.
Compare this to the Panama Canal which started construction under US supervision the same year as the Hudson North River tunnel. They didn’t know much about the spread of tropical deceases but they knew enough to supply their workers with mosquito nets etc. The French effort to build the canal totally failed, primarily because of the high death toll among workers. When the US took over preventing the spread of deceases was a primary concern. And this project now lives in our collective memory as one that costed so many lives.
Now there is no doubt in my mind that working condition for the Hudson North River tunnel were horrendous, and that far too many unnecessary deaths resulted from total disregard of worker safety by the construction company. That this number was 25% and that it was because they didn’t know about decompression sickness... That I don’t buy, dozens of workers dying from the construction company cutting corners, overworking their workers, setting harsh deadlines, not providing safety gears, and (yes) not treating sick workers, that is far more plausible.
I think technology is inherently linked with standard of living which is inherently linked to the value of a life.
He has been working in specialist civil engineering for many years and builds tunnels all over the world. He has told me many exciting and hard-to-believe stories about tunnel construction and tunnel boring machines.
E.g. during the work on the Eurotunnel. Here the British tunnel boring machine was diverted into the rock near half the length of the tunnel and left there. It was cheaper than somehow taking it out again.
Anyways, since my dad is always very stressed due to his job, I am happy to have gained a foothold in IT and not tunnel boring :D
Dara O`Briain has a hilarious stand-up about this: https://www.youtube.com/watch?v=uFglJ3DyqK0
There's one in New York. https://untappedcities.com/2017/02/09/the-200-ton-tunnel-bor...
AFAIK it was not just the cost, but the problem of two TBMs (British and French) meeting head to head. The british were driven out of the way so that the French ones could proceed.
Or maybe it was the toss of a coin? But then a franc or a pound?
If we assume the tunnels are being bored at somewhere near the average of ~100meters/week, and the snail is about ~1000meters/week, that's a 10x speedup in the time to dig right there!
The total length of the three segments is about 9 miles (~14,500 meters)[1], with the last segment projected to open in 2027. Digging started in Fall of 2018[2]. Los Angeles is using what looks like 6 TBMS, two for each segment, to dig parallel tunnels. Segment one completed digging in January of 2022[3], and as of August 2023 Metro has delayed full completion of segment one to 2025[4], therefore it appears that even though digging is not the end-all-be-all, it does take up >50% of the entirety of the construction timeline (~4 years digging + 3 years other construction for segment 1, including stations, track, electrical, and testing).
Using the article as a guide, then, somehow speeding up the digging by a factor of 10 would mean digging could take as little as 21 weeks or ~5 months months, rather than ~4 years, and reduce the project timeline by 50% from 7 years to 3.5 years!
This would be huge for when Los Angeles eventually begins to bore the heavy rail tunnel under the Sepulveda mountain pass, which would be 14 miles, most of it likely tunneled [5].
[1] https://www.metro.net/projects/westside/ [2] https://twitter.com/metrolosangeles/status/10458317962341130... [3] https://thesource.metro.net/2022/01/31/purple-line-tunneling... [4] https://twitter.com/numble/status/1709258555117777016 [5] https://www.metro.net/projects/sepulvedacorridor/
A very interesting youtube channel [1] I recently came across is Cutting Edge Engineering Australia - they do mostly heavy equipment repair/fab.
Some common tools used are air-arc gougers for clean and rapid removal of material along with mill/lathe machining. Had never really considered the conceptual transfer over to something like tunnel boring (air powered debris and rotational removal) but it seems similar.
[1] Repair & Upgrade DAMAGED Bucket for 30T Excavator | Gouging & Welding: https://www.youtube.com/watch?v=qzi7eOr-3lA
I wish we had the "Thunderbirds" Corkscrew TBM. Michael Moorcock writes about subterranian ground-melting craft too in his multiverse 'Oswald Bastable' series.
Deleted Comment
They worked though, and were very fast for their time, still quite fast even by today's standards.
https://www.youtube.com/watch?v=6AV2NcyX7pk
- the main project site: https://hrbtexpansion.org/
- TBM page: https://hrbtexpansion.org/tunnel-boring/
I can no longer find the exact page there that has the details of the TBM but these are pretty close:
- good slide with diagram: https://www.virginiadot.org/VDOT/Business/asset_upload_file1...
- some cool stuff but lots of broken links: http://www.virginiaplaces.org/transportation/hrbt.html