Witness to Vitesse

February 19, 2020 9:30 PM

The Limits of High Speed Rail.
posted by storybored (21 comments total)

A shame physics and shit get in the way.

Super interesting. Though having ridden on an Italian train that hit 300KPM... Woah.
posted by Windopaene at 9:50 PM on February 19, 2020

It would be nice to see that video in HD.
posted by alexei at 10:31 PM on February 19, 2020

having ridden on an Italian train that hit 300KPM... Woah.

Woah... 300 kilometres per minute is damn fast! If they could route it up one of the Italian Alps' peaks, it might get close to achieving escape velocity.
posted by fairmettle at 11:25 PM on February 19, 2020 [1 favorite]

I remember watching the (grainy) web stream of that 2008 TGV record run, it was quite impressive.

"Une fusée sur terre!"
posted by anthill at 11:27 PM on February 19, 2020

Here's more video of the 574 km/h TGV record without dramatic music. Not in HD, alas.
posted by theory at 11:52 PM on February 19, 2020 [2 favorites]

So it's a landlocked vomit comet? Nope, nope, nope, nope, nope.
posted by Beholder at 1:15 AM on February 20, 2020

railroad, more than a decade later? Why has the maximum speed of trains seemed to stagnate at 350 kilometers per hour - yeah, that's really slow, not. Meanwhile in NZ you're lucky to get to 90k, often a lot slower.

I really enjoyed reading the article thanks, lots of great explanation.
posted by unearthed at 1:40 AM on February 20, 2020

What’s the cost of this? Acela non-stop is roughly $115 and tops out at 90kmh each way. Realize this just a test but was curious if it was just as expensive.
posted by geoff. at 3:44 AM on February 20, 2020

The record breaking run wasn't a normal train but an experiment with a minimal train so the costs aren't exactly comparable, but a cheap ticket on the Eurostar from London -> Paris / Brussels is usually around £60-£80 each way.
posted by koolkat at 3:56 AM on February 20, 2020

Realize this just a test but was curious if it was just as expensive.
The TGV is used as a commuter train by lots of people in France. Cheap tickets are... cheap. You can have a Paris/Nantes (340 km) return ticket for less than 30€.
posted by elgilito at 4:22 AM on February 20, 2020 [1 favorite]

That was a neat article... I never thought much about trains and have sort of assumed since childhood that the big limiting factor on their speed and braking distance is weight. I never thought about how minimal the wheel/rail contact area is.
posted by Foosnark at 5:23 AM on February 20, 2020 [3 favorites]

The limits of wheel-rail contact area, and thus the ability for a train to accelerate, has led to some interesting experimental designs. Turbojet trains, for instance, get around this problem by driving the train using the thrust of a turbojet engine. (Note that the "turbo trains" used in the US and Canada were conventionally-driven, powered by gas turbine powerplants rather than reciprocating diesel engines—not the same thing.)

In theory you could have a train with aircraft-like acceleration, although braking would be something of a problem.
posted by Kadin2048 at 11:42 AM on February 20, 2020 [1 favorite]

What’s the cost of this? Acela non-stop is roughly $115 and tops out at 90kmh each way. Realize this just a test but was curious if it was just as expensive.

Did you mean it tops out at 90 mph? While far from 300, that would still be 145 kph.

Also, the Amtrak Michigan Services top out at 111 mph these days (179 kph). Not awful...
posted by Juffo-Wup at 12:25 PM on February 20, 2020

Fastest I've gone is ~430km/h in Shanghai, but thats a very short ride (basically a fancy demo that takes you somewhere useful) and of course is maglev. They don't go into much detail here about the tradeoffs of the designs in the article vs maglev, other than mentioning that of course maglev can (currently anyway) reach much higher speeds (over 600km/h on the SCMaglev, although it's not projected to open for commercial travel until 2027).
posted by thefoxgod at 1:16 PM on February 20, 2020

Top speed is a nice thing for marketing, but not always important in terms of real time-to-destination. Rail lines work best in high density areas and that generally means more stops. When stopped you are going zero kph. What we need is more and more affordable mass transit. These space-shot programs add to expense and defer investment indefinitely while "research" into hyper-whatever moonshot programs are researched at ridiculous cost. TGV is already fast enough. In many corridors it is already pointlessly fast because you spend most of your time at stops ot accelerating from them or slowing down for them.

Maglev is cool for sure, but it doesn't really solve any pressing problems. We need more practical transport and fewer research projects.
posted by sjswitzer at 1:23 PM on February 20, 2020 [1 favorite]

Sure the ticket prices are low, but have you factored in the cost of having a small child locked in the machinery to keep it running?
posted by stet at 1:30 PM on February 20, 2020 [3 favorites]

Specially designed capacitor banks were added to support the autotransformers and absorb the extra reactive power generated by the higher inductive loads of the V150 trainset motors.

I wonder why they didn't use spurving bearings to compensate for the capacitive diractance. Did they have a different method of controlling sinusoidal repleneration?
posted by traveler_ at 2:13 PM on February 20, 2020 [6 favorites]

Top speed is a nice thing for marketing, but not always important in terms of real time-to-destination.

It's crucial for us to decarbonize our transportation system. High speed rail that is comparable in speed to flights for longer distances is very badly needed. There's a huge difference between 150km/h and 350km/h (or higher) in that context. It's also pretty important that the train travel time (including time to get to the station, waiting time, getting from the station to your destination) is faster than just driving and faster speeds matter a lot for that too. Train travel has to be better than alternatives if we hope to get away from planes and cars.
posted by ssg at 2:19 PM on February 20, 2020 [2 favorites]

I was just arguing that time-to-destination is the metric. That means doorstep to doorstep. Frankly, it's not that hard to beat air travel on this metric. You spend about as much time getting to the outlying airport, waiting, boarding, connecting, collecting baggage (if you go that route) and getting to your final destination as you do in the air. For many shorter hauls rail, even conventional rail, beats air travel. Higher speeds are nice, for sure, but they don't really take much off the overall time-to-destination once you consider stops along the way.

In other words, the best is the enemy of the good. There's a lot of that going around in rail transit today (looking at you Musk) and it isn't helping.
posted by sjswitzer at 2:39 PM on February 20, 2020 [1 favorite]

Specially designed capacitor banks were added to support the autotransformers and absorb the extra reactive power generated by the higher inductive loads of the V150 trainset motors.

I wonder why they didn't use spurving bearings to compensate for the capacitive diractance. Did they have a different method of controlling sinusoidal repleneration?

Yeah, I wasn't quite sure who the intended audience for this piece was. Interesting subject matter and a lot of information but written like an undergrad trying to show off.

Author: Iván Rivera works as an engineer

Ah, okay then.
posted by Beware of the leopard at 2:44 AM on February 21, 2020

Specially designed capacitor banks were added to support the autotransformers and absorb the extra reactive power generated by the higher inductive loads of the V150 trainset motors.

Adding to the turbo-encabulator cromulence, I think the author got the technical bits backwards. Capacitor banks supply reactive power, and overdriven motors absorb reactive power (hence "inductive loads").
posted by anthill at 4:42 AM on February 21, 2020 [1 favorite]