I would put money on it using dead reckoning and tunnel markers. Quantum technology isn't something you can hire the lowest bidder to repair or upgrade.
Tube trains could navigate the Underground using the rules of Quantum Physics
61–70 of 83 posts
Re: Tube trains could navigate the Underground using the rules of Quantum Physics
#62At the risk of being näive, Why Tube trains are still a thing? I want underground mini buses, optimizing their stops to the passengers' inside. Most of we passengers go to hub stations. Tubes are like a 100-year old tech without remarkable changes.
Capacity and dwell time. 27 (soon to be 30) trains per hour on the Jubilee line for instance, hundreds of people can get on and off each one.
I don't know why I was downvoted for just asking a question.
I don't get it. Suppose this scenario:
- Instead of big formations, replace each wagon with an electric minibus. - Instead of stopping in all stations, each minibus stops in, lets say 3 or 4. - Each passenger checks into the bus dinamically assigned to their stop. - Minibuses can surpass each other.
You have less dwell time, each ride is reduced to one third of the time.
Re: Tube trains could navigate the Underground using the rules of Quantum Physics
#63The Elixabeth Line runs 24 trains per hour automatically through a 10-station tunnel in central London. It mainly uses axle counters to measure where the train is. https://www.railengineer.co.uk/controlling-the-elizabeth-lin... > The signalling is essentially hands off and is timetable driven. The latter includes GoA3 reversing moves at Paddington and Abbey Wood which are fully automatic as are all entries into and o…
Those odometers would drift as well with wheelslip, unless they are reset any time they enter a known section.
But it’s not an odometer. It’s a sensor on the track that counts axles. The system knows the precise location of the sensor, and how far axles are spaced.
Re: Tube trains could navigate the Underground using the rules of Quantum Physics
#64It's kind of annoying that they don't go into specifics about why this is good. The problem with traditional accelerometers is that the error accumulates, and so even small errors accumulate. The article doesn't really address what makes this different - and in fact I don't think it is different. You're still just measuring acceleration using a sensor and that sensor will have errors that accumulate. So the question…
> I would wager that actually this is probably just a way of funnelling money into research around quantum rather than genuinely trying to solve this specific problem. You’re absolutely correct, from the government’s perspective the interest in the technology is for high accuracy inertial navigation systems for defence purposes, not for the London Tube. If you look at the other companies involved in this project, the…
Given all the GPS jamming in Russia/Ukraine the defense world needs something not GPS based that works. The civilian world also needs this since they are often hit with the same jamming (both as collateral damage and intentional harm to the enemy)
Re: Tube trains could navigate the Underground using the rules of Quantum Physics
#65Earlier quoted context omitted.
At every station at least it should be very cheap to install optical markers that could allow for many opportunities for recalibration.
Agreed, but then said optical markers regularly positioned in tunnels and a map of the tube is enough to position yourself already. That's likely how it works right now, and it's fine.
The article says they just use wheel sensors. Most of them time they don't need to be very accurate so that is more than good enough, but in stations much higher accuracy should be needed and so they need an additional correction there. (note that I said should: I'm a strong believer in automated edge of platform doors which require stopping so the train doors align. Few systems in the world have this though)
Re: Tube trains could navigate the Underground using the rules of Quantum Physics
#66Earlier quoted context omitted.
Capacity and dwell time. 27 (soon to be 30) trains per hour on the Jubilee line for instance, hundreds of people can get on and off each one.
I don't know why I was downvoted for just asking a question. I don't get it. Suppose this scenario: - Instead of big formations, replace each wagon with an electric minibus. - Instead of stopping in all stations, each minibus stops in, lets say 3 or 4. - Each passenger checks into the bus dinamically assigned to their stop. - Minibuses can surpass each other. You have less dwell time, each ride is reduced to one thir…
Your capacity drops dramatically, by at least an order of magnitude if not more. The Jubilee line can do 30 trains per hour, 875 people per train is 26250 people per hour. Say an average minibus can hold 26 people, you'll literally need a thousand busses an hour to move everyone. And yes it all runs at capacity especially during rush hour.
Re: Tube trains could navigate the Underground using the rules of Quantum Physics
#67Earlier quoted context omitted.
> Naturally, trains already have track-based location systems, but they are usually based on a train being within a “moving block”, so their accuracy is down to metres rather than centimetres. If you want to monitor track conditions, the more accurate the location of the suspected fault, the less time staff spend repairing it. Agree in principle though, is this extreme precision really needed?
> their accuracy is down to metres rather than centimetres. If you want to monitor track conditions, the more accurate the location of the suspected fault, the less time staff spend repairing it. Considering the tracks are linear, I would estimate the additional time needed to locate a fault within two meters as compared to two centimeters at "negligible". On the alternative assumption that the faults are too small f…
Do they repair track cracks? I'd expect they replace the entire track section - both rails - as long as they are there. Get within however much they can do in a work shift and good enough.
Re: Tube trains could navigate the Underground using the rules of Quantum Physics
#68If you have fixed beacons with a known location, couldn't the devices work out their location? Seems like an engineered solution to rely on "quantum".
As others have suggested: this is a test for military technology. When the enemy has jammed your fixed beacons you can't work out your position from them. Probably nobody will do this on a train (and they have other technology anyway), but for an airplane this is a real problem.
Re: Tube trains could navigate the Underground using the rules of Quantum Physics
#691.25 millions doesn’t even buy you the laser to cool the atom gas. It’s for sure interesting, but to put this on a train, we will have to solve a few more questions. like for example, how do you operate an optical table on a bumpy metro.
Those are the important questions that the people who need this need answered. Trains have better options than this, but there are some applications that don't and trains are an easy place to test whatever you are trying, if it works on a train you can then build the real thing (which is often an airplane or missile - with power an weight limitations that don't apply to trains)
Re: Tube trains could navigate the Underground using the rules of Quantum Physics
#70Earlier quoted context omitted.
I don't know why I was downvoted for just asking a question. I don't get it. Suppose this scenario: - Instead of big formations, replace each wagon with an electric minibus. - Instead of stopping in all stations, each minibus stops in, lets say 3 or 4. - Each passenger checks into the bus dinamically assigned to their stop. - Minibuses can surpass each other. You have less dwell time, each ride is reduced to one thir…
Your capacity drops dramatically, by at least an order of magnitude if not more. The Jubilee line can do 30 trains per hour, 875 people per train is 26250 people per hour. Say an average minibus can hold 26 people, you'll literally need a thousand busses an hour to move everyone. And yes it all runs at capacity especially during rush hour.
Lets call them buses instead of minibuses and each one has the same capacity of a wagon.
Instead of 10 formations of 6 wagons you have 60 buses.
You have same capacity and one third of traveling time per ride.