Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The Evolution of Tunnel Boring Machines

construction-physics.com

Post reply on HN
Print view View original

71–80 of 127 posts

Re: The Evolution of Tunnel Boring Machines

#71

Post by foota »

Animats wrote: post #62
foota wrote: post #56

Earlier quoted context omitted.

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 car…

I guess I'm trying to understand how much of an opportunitythere is here, and assuming the existing tunnel boring companies have at least considered this, I guess the most possible gain you could get out of this would be whatever it would cost to pay people to do it manually (otherwise, the pros would out weight the cons, and a company would have done it that way). But I wouldn't have thought it would cost that much to have people do this, so Im left unsure how large the opportunity is here.

Re: The Evolution of Tunnel Boring Machines

#72

Post by ofrzeta »

related: documentary on the Gotthard base tunnel:

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.

Re: The Evolution of Tunnel Boring Machines

#73

Post by zardo »

jauntywundrkind wrote: post #52

Anyone else immediately search for Subselene, the nuclear-powered thermal tunnel boring idea proposed in 1986? 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. https://www.osti.gov/biblio/5262838

75000 horsepower is more than a couple.

Re: The Evolution of Tunnel Boring Machines

#74

Post by teruakohatu »

runarberg wrote: post #60
cyberax wrote: post #40

Earlier quoted context omitted.

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.

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…

I can believe it, and I can believe it is still in the collective memory of the relevant unions since it is apparently partly the reason for their existence. From NY Time Archive: [1]

> 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...

Re: The Evolution of Tunnel Boring Machines

#75

Post by aorloff »

Animats wrote: post #51

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 car…

zinger

Re: The Evolution of Tunnel Boring Machines

#76

Post by s1artibartfast »

runarberg wrote: post #60
cyberax wrote: post #40

Earlier quoted context omitted.

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.

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…

It seems plausible to me and the Panama canal is a good comparison. 30,000 workers dies building the canal, which was 40% of the workforce.

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.

Re: The Evolution of Tunnel Boring Machines

#77

Post by s1artibartfast »

mschuster91 wrote: post #53
Retric wrote: post #49

Earlier quoted context omitted.

Assuming I am reading this right in 1905 1/4 of male workers over 16 made 8$/week or less. https://babel.hathitrust.org/cgi/pt?id=nnc1.cu56779232&seq=1... For unskilled labor 6 days a week at 2.50/day = 15$/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…

> It’s worth remembering when doing inflation calculations just how poor people used to be. 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 s…

And if we are talking late 1800's/early 1900's, Taxes were essentially non-existent, so people kept and spent more of their money. Taxes as a % of GDP was in the 5-10% range, opposed to ~40% today.

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.

Re: The Evolution of Tunnel Boring Machines

#79

Post by kiba »

Retric wrote: post #68
kiba wrote: post #58

Earlier quoted context omitted.

Lifestyle inflation, urban planning, and choices makes living a quality life more difficult than it should be. 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…

Lifestyle inflation is why people don’t feel so much wealthier than their grandparents, but housing isn’t the economic drain it seems like because so much of its value doesn’t require resources to create. It’s mostly redistribution of income from workers to other people and as such it gets into politics. Well that and the giant ball of suck associated with long commutes, but I am kind of hoping there’s going to be mo…

If you increases the income of workers that's going to go to right back into housing, unless you made changes on how the housing market works.

Re: The Evolution of Tunnel Boring Machines

#80

Post by _8j50 »

lstodd wrote: post #59
_8j50 wrote: post #45

Does anyone know why such machines aren't being used to create artificial rivers? It seems civilization and therefore economic activity follows where fresh water sources are. And there is already a problem in the US west with water shortage.

A river is mostly its watershed and not the waterway which while very visible doesn't matter that much. No amount of machines would help create the watershed, so no, there's no point.

There are lakes such as superior in michigan or even mammoth lakes in cali. I also wondered why not instead of recycling desalinated water after use, have it fill up a lake. Use nuclear powered (dedicated power plant) desalination to fill up artificial lakes.

People talk about colonizing mars but if we can't even do this on earth then how is that more practical?

Post reply on HN