The Evolution of Tunnel Boring Machines
construction-physics.com
construction-physics.com
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]
A perhaps very stupid question, but why not make the cars self-driving the way we built self-driving robots from LEGO as kids? That is, line-following cars. It's effectively a virtual track - but I imagine painting a line or building it from cheap plastic would be cheaper than putting actual rail tracks in, and unlike generic driving automation, line-following is an old, well-understood and solved problem.
tired vehicles
I see what you did there.
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.
Tolerance for workers death is highly related to location and time. We used to have large families for a reason!
N=10, but nevertheless a comparison on the difference in location at exactly the same time was the Channel [0], of the 10 deaths, 8 were in Britain.
[0] https://en.wikipedia.org/wiki/Channel_Tunnel#:~:text=At%20th....
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.
> In 1890, 68 sandhogs died as they bored a gas tunnel under Welfare Island, now Roosevelt Island. A Manhattan coroner estimated that at least 50 sandhogs died in the first five months of 1906 in the construction of Pennsylvania Railroad tunnels. Thirteen sandhogs died building the Holland Tunnel between 1921 and 1924.
So they lost 10 per month building the Pennsylvania Railroad tunnels. The 25% probably refers to the underground workers, not everyone employed on the project. Either there was greater automation, or by the 1920s the numbers lost decreased substantially.
[1] https://www.nytimes.com/1993/11/28/nyregion/tunneling-into-w...
I just think that even during this horrible time period, you still couldn’t get away with loosing 25% of your workers while still getting the job done.
It is a lot easier to replace a few dozen men digging tunnels in New York, than find 30,000 replacements in a swamp and jungle.
Life was simply cheap. If you go back 75 years further, you had pretty similar documented death rates for sailors - especially in the slave trade where a 25-50% death rate during Atlantic slave crossings was pretty common.
<https://en.wikipedia.org/wiki/Health_measures_during_the_con...>
The transmission of yellow fever by mosquitos was established by Maj. Walter Reed, US Army, the physician for whom Walter Reed Hospital is named:
<https://en.wikipedia.org/wiki/Walter_Reed>
The shear lethality of tropical diseases to Europeans prior to the 20th century really cannot be overstated. I'd run across a statistic that the life expectancy of a British soldier stationed to Africa was on the order of six months:
In 1824 half the 600 soldiers garrisoned in the Gold Coast died within a few months, and the House of Commons was told in 1826, that of 1,567 troops sent out in the previous two years, 905 had died. Europeans died mainly from malaria and yellow fever - or from the “cures” which were nearly as dangerous as the ailments. Blood-letting was common. Leeches were standard colonial surgical equipment, being placed on the patients shaved head to “suck out” the fever. Great blisters were raised with steaming cloths or mustard packs and then broken to drain away the fever. On the same principle, salivating was induced by calomel, often at the expense of the victim’s teeth, or by quicksilver and mercury, an even more drastic “treatment” that inflamed the mouth and sometimes caused the sick man to suffocate on his own swollen tongue.
<https://web.archive.org/web/20070106173014/myweb.tiscali.co....>
Drawing a distinction between death by disease and by accident may be somewhat arbitrary, but still seems a distinction worth noting.
Both the tunnel and the canal (under USA supervision) didn’t start construction until 1904.
But that said, by far the majority of the deaths during the construction of the Panama Canal were under French supervision, in the 1880s. This effort failed primarily because of the heavy toll on human lives. While people did die under the Americans, and while labor conditions were horrendous, it was nowhere near on the same caliber as the decades prior. Further indicating that you cannot just disregard human lives completely and still get the job done (you could only do that to an extend; until July 6th 1935 that is).
I think what is interesting is the expansion from purely logistical/financial implications to include other considerations.
These other considerations including legal ones, as labor laws were passed, civil liability law developed, social sentiments changed, and welfare increased so that people didnt have to choose be 50% chance of death or starvation.
Operational safety based risks, such as experienced in direct earthworks, blasting, transport, etc., disproportionately affect front-line workers.
Infectious disease based risks are largely indiscriminate between front-line and managerial staff. That is, unskilled labourers and administrative, clerical, officer, etc., staff all largely face a similar threat against vector-transmitted diseases. The only option for the latter is to avoid the location or posting entirely.
That may be a subtle shading, and points about the US NRL made by runarberg are well taken, but again, it seems significant.
Note that tropical diseases were an issue across the Panamanian isthmus for travelers and transport workers (sailors, teamsters, railroad) who traversed the region even before the canal was built, as an overland leg in the East-to-West-coast route which avoided both the time and perils of going 'round the Cape, encircling all of South America.
A railroad was opened across the isthmus in 1855. That effort cost 5-10k workers' lives itself.
<https://en.wikipedia.org/wiki/Panama_Canal_Railway>
And, somewhat supporting your viewpoint, Adam Smith describes the career duration of workers at his time (~1750--1775): "A carpenter in London, and in some other places, is not supposed to last in his utmost vigor above eight years."
-- Adam Smith, Wealth of Nations, Book 1, Chapter 8, "Of the Wages of Labour"
<https://en.wikisource.org/wiki/The_Wealth_of_Nations/Book_I/...>
Similarly, prior to the development of modern sanitation and hygiene (fresh water supplies, sewerage systems, regular bathing, handwashing), cities were net population sinks and relied on in-migration from surrounding countryside (often driven by limited employment and income potential there) in order to simply maintain population levels. Infectious disease deaths within cities could top 50 thousand per year in 19th century London and New York, out of populations of 1 million or fewer.
Now that's interesting. I consider myself dark realist when it comes to history but I haven't read that. I'm guessing it must be constrained to some pretty specific circumstances and period in time.
<https://archive.org/details/farewelltoalmsbr00clar/page/92/m...>
Specifically, that situation prevailed from the 16th through 19th centuries. That's a brief period from a geological standpoint I suppose...
<https://www.worldcat.org/title/farewell-to-alms-a-brief-econ...>
Not at all. When you are a worker in the jungle, you will get biten by way more mosquitos, than when you are sitting in a office protected by mosquito nets.
I think technology is inherently linked with standard of living which is inherently linked to the value of a life.
For unskilled labor 6 days a week at 2.50/day = 15$/week which would have been quite tempting especially if the risks where unclear.
It’s worth remembering when doing inflation calculations just how poor people used to be. Take the average person’s budget today and remove their car, gadgets, AC, subscriptions, most of the pricy food options, etc. Healthcare was cheap and largely ineffective, collage was rare and minimalist by todays standards. Most of what people spend money on today simply didn’t exist so not having it was normal.
And also, how much of the wealth created by the employees ended up in their pockets vs. the pockets of the owners, and how the standards of living were. Basically, back then with such a job you could afford a place to live, to have kids, a wife to take care of housework and, post 1930-ish, a car. Today? Most of my generation struggles to make rent because we're being bled dry.
You're able to afford a larger house and a car or two, but you're also spending more money than necessary on transportation and housing. Buying a car is expensive and so is the road built for cars. Trains are more expensive than a car, but its cost can be amortized across many riders.
Housing is a problem of both government and market dysfunction and is directly tied to our transportation woes. People are tied to the idea of real estate as an investment which means they often opposed development. Planners continued to zone only SFH, and made middle housing illegal. They also don't do mixed zoning which improve efficient utilization of land.
I supposed if income goes to workers more, they would just push the housing price higher. It can't be fixed unless we build sufficient housing.
Well that and the giant ball of suck associated with long commutes, but I am kind of hoping there’s going to be more pushback on that due to people working from home during COVID. Even those who still needed to go in had vastly less traffic.
On top of that all the nice things have gotten cheaper. Listening to music is now cheap. Books, news, entertainment are cheap.
Yes you may have had a car (24 million cars in 1940 v 135million population) but then you wouldn't have had a fridge, TV.
And youre comparing someone relatively wealthy, to someone who can't afford rent. If you were poor you probably didn't have electricity, indoor toilet, more than one heated room in the house, and probably lucky if you could afford enough food.
I'm from the UK and we went through this a bit later so it's still within living memory. My dad remembers getting an indoor toilet an plumbed in bath for the first time, that was late 50s/ early 60s.
They also didn't have to worry about the same healthcare costs, as they were healthier in general, and the options were far fewer when sick.
Source? Survivorship bias?
How many people do you know who've had polio? Small pox? Rubella? Mumps? Died from a bacterial infection? Blinded from cataracts?
>They also didn't have to worry about the same healthcare costs, as they were healthier in general, and the options were far fewer when sick.
People were less obese, spent less time battling disease, and died younger.
It's somewhat similar to survivorship bias, but it is a real effect.
You can look up population incidence and prevelance rates for diabetes, obesity, alzheimer's, and cancer yourself.
Yes they were less obese, the issue was the more likely to be the opposite, malnutrition. I dispute they spent less time battling disease, but if they did, it's because they died quicker.
Alzheimers is a disease of the old, and cancer tends to be also.
So all you're left with is obesity and the closely correlated diabetes.
Often someone would be dealing with the consequences of childhood illnesses or injuries for decades.
Polio is a good example of the opposite, because polio today is effectively zero. Most other types of disease trend the other way with much more significant margins.
Polio lead to some level of paralysis in somewhere between 0.5-0.2% percent of people, many of whom died and needed no further healthcare.
Today, a far larger percent of Americans have lost the ability to walk due to obesity and diabetes.
Tuberculosis, Measles, Mumps, Rubella, Cholera, Polio, Smallpox, Tetanus, Varicella(Chickenpox> shingles), etc didn’t individually leave large segments of the population with serious lifelong issues, but collectively they added up. Add in a little cut or malnutrition and even diseases we don’t normally consider serious would more frequently have huge long term health impacts.
Very few young people lose the ability to walk from obesity, that’s generally something that impacts older people who were able bodied up to that point. Infectious diseases however generally hit the young harder more than people with fully developed immune systems.
Do you think randomly selected sample of people from today or 1923 would win in sports competition?
Pick 10,000 random people from each time period. 2023 would probably win a tug of war. Increased heigh and obesity not being as detrimental as being under weight.
Cardio would presumably go to 1923. However what percentage of people could walk 1 mile could go either way. Someone that’s paralyzed can’t do it but someone that’s fat need to be motivated.
I agree the strongest would be 2023.
I agree that health can have complex and variable definitions. It is also very different than life expectancy.
One measure of health may be baseline fitness and ability to care for ones self. Alternatively, health could be freedom from disability, pain, and health related suffering.
Another definition of health, which I was originally getting at, is how many people rely on continuous medical services to remain alive. That is to say, how many people would drop dead if they stopped receiving medication and medical services.
This baseline, pre-intervention health is relevant if you want to compare health costs.
I agree that it is different that post-intervention health, which might be the most relevant of you want to consider something like quality of life.
It is a shame we dont have better data from the earlier 20th century.
There's probably a data set for that around somewhere
As a kid I remember visiting a friend who lived in an old workers house. I was in awe to see such a small house, and in shock to learn they actually bought two houses and connected them.
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.
They worked though, and were very fast for their time, still quite fast even by today's standards.
- 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
Also the idea of adding grout between the rough bored tunnel and the tunnel lining - what a great way to create a full physical connection given the probable irregularities of the tunnel.
I tend to think they pretty heavily underbid how much heat input it would have taken? The design review for a 3m diameter tunnel going 30/m a day was 56 MW. I am not an expert, but a couple horsepower of thermal energy seems low to melt through the moon.
[0] http://atomic-skies.blogspot.com/2012/07/those-magnificent-m...
https://www.youtube.com/watch?v=TaYtrsvzfh0
better video, only German though:
https://www.youtube.com/watch?v=93O7YmBEb7A
The last video is also interesting to watch today because they mention a lot of the safeguards they put into the system (such as measuring the temperature of the train axles some km before they enter the tunnel and redirect the train to the old Gotthard track if the temperature higher than some threshold).
But still recently on August 23 there was this accident where a freight train derailed inside the tunnel.
People talk about colonizing mars but if we can't even do this on earth then how is that more practical?
Yes. Lakes as a concept exist. There are many examples. What are you proposing?
> I also wondered why not instead of recycling desalinated water after use, have it fill up a lake.
Okay. Just for the aesthetic value? Or to evaporate it?
Let me get it straight: you are proposing to pipe the output of wastewater treatment plants to an open basin (also known as artificial lake). Ones whose waste input was generated by humans drinking desalinated water. So your proposal is to desal, consume water, turn it into waste, clean waste, fill lake. Do I understand you well?
And you are asking “why not”. Let me turn it around: why exactly?
> People talk about colonizing mars but if we can't even do this on earth then how is that more practical?
It is not.
Rivers from the lakes to unpopulated arid or drought striken parts of the country.
> Okay. Just for the aesthetic value? Or to evaporate it?
To use it to create a fresh water source that will feed a river. The evaporation I perhaps wrongly assumed will become rain somewhere relatively near by? But even without that, my assumption is most arid places were green at some point, re-introducing water will green them up and make them habitable for humans and generate economic activity. Salton sea in california, as disastrous as it is for example, you will see a lot of farms next to it in the middle of the desert!
> Okay. Just for the aesthetic value? Or to evaporate it? Let me get it straight: you are proposing to pipe the output of wastewater treatment plants to an open basin (also known as artificial lake). Ones whose waste input was generated by humans drinking desalinated water. So your proposal is to desal, consume water, turn it into waste, clean waste, fill lake. Do I understand you well?
Minus the last cleanup part (except for debris). Our "waste" (not trash but toilet waste), can fertilize soil but also st high enough desalination volumes we wouldn't need to recycle water. But to meet the aforementioned need of artificial fresh water generation, we can use our waste. In cities we are already doing this except it mostly just feeds into the ocean or a bigger existing natural river, instead of that, we fill up waste lakes that drain into artificial rivers and now that water and nutrient helps grow plants, farms,etc...
If we make it work, everybody wins. More green, cooler planet, better economy, more housing along artificial river paths, transport,etc...(my original idea was actually to create these rivers next to interstate highways and gradually build high speed rail as well.
Much of the US is empty and unpopulated because there is no fresh water supply or doil that can sustain crops of any kind and we have growing national and planetary crises that might be alleviated by this including jobs,housing, climate, wars over resources,etc...
It is being moved out of there in such amounts that no economically possible diversion of water flow can overcome this. Cf the crazy and eventually buried USSR project of diverting north-flowing rivers water to the Kazakhstan from 80s.
That could not work even in theory, where the talk was about thousands of cubic meter per second and you suggest that some toilets can make this work. That is just not possible. Maybe if the climate actually changes, some of those lands will become good enough for agricultural use. But not now.
The correct comparison should be comparing for each area and situation, which type of transport investment results in the greatest utility. The objective is not to minimise traffic, but to maximise peoples ability to get where they need to be.
But, many studies have shown that building more roads does not reduce congestion. Congestion is not function of roadway space-- other factors like accidents, merging, exiting, peak travel capacity, etc greatly impact congestion. Building another lane on a highway doesn't solve the problem.
Or of course better public transit. The vast majority of what people are driving for could be done without driving if transit was better.
TL;DW No. Tunnels are hard to rapidly dig (esp. in the US where property rights exist underground), they require safety elements like proper ventilation, and they are still subject to congestion at the destination exits.
Climate change is correlated with worse crops because it brings more droughts and harsher weather extremes and this will become a real problem.
very much a noahs ark scenario, but we may best use a number of avenues, such as exoplanetary colonies.
IIRC we've not even found one that has free oxygen in the atmosphere yet. Even if we did, anything with that and water would be extremely exiting by the standards of exoplanets, even if it had an average temperature of 75 C which would kill humans.
But I wouldn't underestimate the multitude of ways in which this planet could be made inhospitable by us.
We are trusting a lot on the self-correcting power of nature on this planet, but we just don't know if there isn't some tipping point after which there is no return.
That's yet to be proven - although not in my lifetime, I hope. One would hope that humankind would finally manage to do something before it gets as bad as on Venus, but I wouldn't bet on it...
Even if we burned 100% of all biomass on Earth, leaving it dead, it's still not close to Venus, where the "air" is so thick it's passed the critical point and no longer distinguishable from a liquid.
Even if we did that, the day length on Venus is longer than its year.
It becomes really tangible just how much we drank the kool aid of capitalism when people can more easily imagine moving ontonexoplanet colonies than a future where the gain of the few capitalists isn't literally priorized above the survival of the human race.
Why do you think the next planet won't fall victim to the same mechanisms?