New Gotthard tunnel garners worldwide admiration
swissinfo.ch
swissinfo.ch
We have a major issue with rail transportation in the US. It's most useful in cities in a grade-separated form, but it's simultaneously the hardest to build in cities in a grade-separated form. The number of existing pipelines, power lines, traffic reroutes, building permits, and private property consents required to check out grows to dizzying levels of complexity.
One way to bypass this is to dig deep, deep tunnels. Tunnels far enough down that surface settling doesn't occur, tunnels far enough down to bypass skyscraper pilings. To do this well, though, you need to construct as much of each station as possible in the tube itself, and only sink shafts down to that level, not whole horizontal rooms.
You can do that with a ~20m diameter TBM. You buy this monster of a machine for an exorbitant amount of money, and in exchange you get to leave the walls that it constructs in place, except for some vertical elevators and a vertical stairwell directly to the platform; No blasting, no extensive bit-by-bit excavation, no surface trenches, no access tunnels, no adjusting to separate mud and soil and rock. Just two tracks in a big tube with a bunch of space in between them, and maybe a second level for another pair with an express line.
As someone who grew up in Washington DC and moved to NYC, it was immediately and obviously noticeable. The ability to just hop down a few stairs and jump on a train is a major improvement to convenience. The multiple levels, elevators or long, long escalators, and so on, can double or triple the amount of minutes it takes to go 3-4 stops.
Their progenitor, as I recall, went to the great lengths of riding them aboard a wheelchair every day in a pained attempt to prove to the planning committee that elevators, which would have spoiled his precious vaulted look, were not necessary.
A ten-car train in an urban commuter rail system might have 40-80 passengers per car. That's up to 800 people deboarding (say, for a downtown terminal station), though generally you're looking at a low few hundred.
Dumping that demand onto 3-4 escalators is doable, and the streaming is continuous. For elevators, I don't see it working. Too many people and elevators don't operate continuously as escalators do.
Unless there've been tremendous advances I'm unaware of.
Schindler's high-capacity elevators are rated for 6-21 people. It would take 38 elevator trips to empty the train I described above (divide among multiple shafts and/or car trips as you like, but realize that speed is 1-1.6 m/s (about 3.6 mph), or just over 60s to travel 100m, plus return and dwell time. If train service intervals were ten minutes, you'd need ten shafts assuming 3 minutes per round-trip to clear 800 passengers.
http://www.schindler.com/content/pl/Internet/pl/modernizacja...
http://en.wikipedia.org/wiki/Paternoster
:)
Video from the link (in Japanese):
The Hitachi version is interesting because it incorporates the behaviour one expects from standard elevators, at the cost of some speed.
It sounds ideal for a mass transit station, and it could use the same pattern as is currently used for subways (a small time it remains motionless, then the doors close after a beep).
I found an English version of their video
https://www.youtube.com/watch?v=mnX5WZhvzZY
and ThysenKrupp is also working on a similar idea:
http://rt.com/news/210143-maglev-horizontal-elevator-thyssen...
Though Hitachi has decided to focus on speed instead:
http://www.smithsonianmag.com/ist/?next=/smart-news/worlds-f...
I hope the innovation in this space doesn't dry out :)
I'm familiar with a few such incidents (friends were witnesses, I, fortunately, was not), with conventional elevators, overloaded. The screaming, and then lack, is apparently something not easily forgotten.
A series of cars, in parallel shafts, with safety lockouts, and capable of reasonably streamed operation, might work. It would be complex, but then most options are.
Extrapolate that to a ~100m depth for a wait of 8 minutes 15 seconds, with a ~200m horizontal span that needs to be excavated manually all the way to the surface - you probably need one to two city blocks of demolition for a 30deg escalator.
There are some high-speed elevators out there, at these heights we're strongly limited by comfortable acceleration (at the highest peak speeds from Mitsubishi or Toshiba you'd be talking about upwards of ~15m/s, but you couldn't safely reach those at this height). 1m/s^2 seems to be okay. That puts a half a trip at 10 seconds, or 20 seconds from when the doors finish closing to when the doors begin opening. Figure 25 seconds on either end for filling and emptying, and you have a 90 second round trip. Expect something like 4 20-person elevators for typical stops, to maybe 16 for an inner-city transfer station, and you can move 50-200 people per minute.
According to Metro, a single escalator can move 90 people per minute; They typically pack 2 escalators and a stairwell, or 3 escalators running 2-1 peak flow, into a shaft, but escalator availability ran as low as 60 percent for a number of decades before a recent improvement drive (now ~92%), so you had good odds that at least one was broken (or, in optimistic parlance, 'had become stairs').
The Japanese started engineering for this as well when they went through a bonanza of submerging rail lines in Tokyo. At first, they started digging super deep with smaller tunnels (the trains use a linear motor/reaction-rail for much tighter loading gauges). However, they started to realize that it made the the now submerged trains more inefficient to be so deep. More recent lines are elevated or much more shallow.
For instance, the Cascade tunnel in eastern Washington (http://en.wikipedia.org/wiki/Cascade_Tunnel) can only handle ~one train per hour because they basically have to replace all the air in the tunnel every time, which takes about a half hour even with giant fans.
Tunnels, especially deep ones, are also extraordinarily expensive, that's why modern rail is built on viaducts, not in tunnels, because it's just much much cheaper.
It's like saying you could build all roads in tunnels because Tesla sells cars.
In terms of intercity traffic, unless there is a compelling reason to tunnel it should be level or slightly raised, with the road crossings going over or under (since road vehicles are better at accelerating and decelerating when climbing or going down grades).
Here is a telling quote about why digging deep is the wrong answer.
"Seattle, however, is building an entire light- rail line underground from the University of Washington to downtown Seattle. When completed in 2016, the line is expected to cost $628 million per mile, yet it will not carry any more people per hour than San Diego’s original 1981 light-rail line that cost $17 million per mile.
The total cost of the 3.1-mile subway would be enough to build almost 200 miles of elevated busways at $10 million per lane mile. Seattle’s first light-rail line, which opened in 2007, was also completely separated from streets, costing $175 million per mile (nearly $200 million per mile in today’s dollars)."
[1] http://object.cato.org/sites/cato.org/files/pubs/pdf/pa750_w...
Closer to me, I've previously complained about the bridges across the Columbia river between Washington and Oregon.
In 1982 a very fine bridge was built for $172 million.[1]
What finally got scuttled in 2013 was a different proposed bridge that would have cost $2800 million.[2] Now I understand there was some intervening inflation, but there was a 16x cost increase (before inevitable cost overruns) between the two projects.
Government at all levels, federal, state, municipal, is a very poor steward of Other People's Money.
[1] https://en.wikipedia.org/wiki/Glenn_L._Jackson_Memorial_Brid... [2] https://en.wikipedia.org/wiki/Columbia_River_Crossing
In other news, Crossrail finished tunnelling today. Not as long as this but still a big project.
http://www.crossrail.co.uk/news/articles/prime-minister-and-...
The slogan means "no special rights for foreigners", in protest of a practice that allows foreign residents in switzerland to sign petitions to open up a non-binding resolution in local city councils.
I don't think I've seen such baldly racist imagery from a US political party in my lifetime - it looks like WW2 propoganda.
As an American (who has also spent a lot of time in Switzerland) I agree that it's shocking. But, I think it's also a little understandable. There is a strong desire to preserve swiss culture. Switzerland is a country with a history and culture stretching back into antiquity. In the US, we are a country of immigrants.
Crossrail tunnel already smells of urine
http://www.thedailymash.co.uk/news/society/crossrail-tunnel-...
http://www.ianvisits.co.uk/blog/2014/02/02/how-a-tube-statio...
They've recently created some new shops at Canary Wharf Tube, and there is now a fancy Neal's Yard shop right where the Gents toilets used to be.
As tunnel projects go, it was a long drive, but not an unusually difficult one. Mostly hard rock, some water problems, but not too much water. Many tunneling projects are more about keeping the water out and the roof supported than digging.
Surprisingly, it was just a 4 TBM job, two tubes cut entirely from the ends. Although there are several vertical shafts down to emergency stations, those were not used as TBM starting points. Each TBM had to grind forward for almost 14 years.
[1] https://www.alptransit.ch/en/status-of-the-work/railway-infr...
I'd like to know more about this.
In 2012 they seemed confident to open in 2016, but I can't really find the reasoning for that. As far as I can see there were also cost considerations playing a part in the decision.
Edit: apparently a very difficult Dolostone section was less proplematic than anticipated (again, couldn't find an english source for this)
[1] (in three languages but no english, sorry): http://www.parlament.ch/r/mm/2007/Paginas/mm_2007-04-27_9519...
When completed, it will be the world's second largest tunnel, only shorter than this one.
They weren't able to dump the water directly into the local river because it would disrupt the native trout, and so they cool it with the greenhouse and farm.
If I remember right the greenhouse and farm were businesses started by the engineers that were on the tunnel project.
The caviar is nice - not as much minerality as normal, but still good texture and taste.
So while the tunnel is at surface level at the entry and exit points, for the majority of the distance it's many thousands of feet deep. It's about 15 degrees F per 1000 feet, so if it's 5000 feet below the average height of the mountain range then you might expect the tunnel to be 75 degrees F warmer than the surface.
If the average surface temperature is say 50F then adding 75F gets you to 125F which isn't enough to boil water or generate electricity (efficiently) but it's definitely hot enough to warm a lot of things in a meaningful way.
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[0]: http://www.dutchamsterdam.nl/691-amsterdam-north-south-metro