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posted by Fnord666 on Saturday May 19 2018, @03:48PM   Printer-friendly
from the everyone-say-whee dept.

Elon Musk pitches 150 MPH rides in Boring Company tunnels for $1

Earlier in the evening Musk retweeted an LA Metro tweet that said it's coordinating with The Boring Company on its test and said the two will be "partners" going forward. Much of what Musk discussed about how his concept in-city Loop would work has been answered in concept videos and the company's FAQ, but he specifically said that the plan is for rides that cost a $1, and carry up to 16 passengers through hundreds of tunnels to those small, parking space-size tunnels located throughout a city.

The big problem is digging those tunnels to start with, and while part of the session included video of a speedy test run through the tunnel Musk has already dug on SpaceX property, the plan is to pick up the pace. Davis said Musk has challenged his team to match the digging pace of a snail (0.03 MPH), and get up to 1/10th of the average walking speed of a human at about 0.3 MPH -- compared to its current top speed of about 0.003 MPH.

Previously: Elon Musk Wants to be Boring
Elon Musk's Boring Tunnel Near Los Angeles


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  • (Score: 3, Informative) by Nuke on Sunday May 20 2018, @10:44AM (2 children)

    by Nuke (3162) on Sunday May 20 2018, @10:44AM (#681831)

    If you examine the speeds of subterranean rail systems in cities such as London, Chicago, Atlanta, etc., you will find that they move mostly somewhat slower than 150 MPH.

    I know exactly what London Underground trains can do; as a test engineer I have driven them. In fact I claim the speed record for driving one - 86mph :-)

    Stations on the London Underground are typically a mile apart, sometimes two miles in the suburbs, and as little as 250 yards in the centre (Charing Cross to Embankment). It would be utterly pointless, impractical, and in many cases impossible, to accelerate to 150mph between stations. The speed of the service (ie how long an individual passenger's journey takes) in the final analysis is largely dictated by the speed at which people leave and board the trains, even though regular commuters undertand that and are pretty good at it.

    Conventional city underground [or subway] trains can be boarded in the extreme case by 1000 people as simultaneously as the door widths allow (nearly 50% of the side of a London Underground train). Compare Musk's 16-people carts. One arrives at a station platform (or whatever Musk wants to call them, and the lift-to-the-surface idea would be even slower); assuming the platform is longer than one cart, another cart pulls in behind after a 2 second (or 2 minute, or whatever Musk proposes - makes no difference) interval. The second must stop behind the first unless that interval is longer than it takes for passengers to get in and out*. Then a third pulls in and must stop behind the second, even if the first cart has already left. Progressively, the carts arriving will back up and soon they will be stopped in the tunnel before they reach the platform - in other words queueing to enter the station even if the leading end of the platform ahead is by now empty

    A solution to this would be to link the carts together so they enter and leave as a block - oh wait, we have re-invented the train.

    I know Musk proposes that passengers are grouped to common destinations, so their cart skips stopping at other stations. But they won't escape being delayed in that queue, unless you build passing loops at every station - except that the popular stations will still cause that tailback onto the through line, and even if not, the "150mph" through carts will be hampered by the acceleration and deceleration of carts ahead of them leaving for the loop or joining from it.

    As for 150 mph in tunnels, European high speed trains are doing more than that in tunnels every day, but they are not city subway trains.

    * In which case, with 16 passengers at a time, the capacity of the system would be miniscule.

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  • (Score: 0) by Anonymous Coward on Sunday May 20 2018, @01:45PM (1 child)

    by Anonymous Coward on Sunday May 20 2018, @01:45PM (#681855)

    > Then a third pulls in and must stop behind the second, even if the first cart has already left.

    Thanks for the summary, all good as far as it goes. But you are a using a linear or serial model based on one track (in each direction). Since these are "cars" that run on a fairly normal flat road and not "trains" on tracks, there is no elevated platform and additional cars pulling into the station can just pull up alongside other cars. As soon as any car is full (or full enough, off-peak) it can leave at any time, as long as it leaves suitable headway between cars. If any station gets too busy, just dig some more and make it wider.

    Separate question, what are typical loading and unloading times on the London Underground?

    • (Score: 2) by Nuke on Tuesday May 22 2018, @10:48AM

      by Nuke (3162) on Tuesday May 22 2018, @10:48AM (#682595)

      London Underground trains can have doors open for as little as 10 seconds if there are not many passengers around. OTOH at a busy station in the rush hour it could be a minute, or more if there is a total log-jam of passengers. It is this time that is the main limit on the service frequency, which is typically 2 minutes on busy stretches, although I have seen as little as 90 seconds - ie the next train is pulling in as soon as the previous has left the station.

      Good point about the parallel "roads" in the station, although it is nothing to do with whether it on rails or not, or whether there are raised platforms or not. Parellel roads are used at both busy conventional railway stations and at road bus stations. But it does add a lot to the expense of the station in terms of surface land area or underground tunnelling. Under London it is difficult to find more subterranean space these days with so many existing tunnels, sewers, cable tunnels and tower block foundations, and I guess it is similar in many other cities.