[HN Gopher] The short-lived experiment with rubber tires on rail...
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The short-lived experiment with rubber tires on railways (2013)
Author : montalbano
Score : 26 points
Date : 2023-10-02 06:48 UTC (1 days ago)
(HTM) web link (www.ianvisits.co.uk)
(TXT) w3m dump (www.ianvisits.co.uk)
| somat wrote:
| The fun experiment was the paper wheels.
|
| https://en.wikipedia.org/wiki/Paper_car_wheel
| jjgreen wrote:
| Still in use on a few lines of the Paris Metro
| azdle wrote:
| As far as I can find, the Paris Metro's rubber tire lines all
| run on special rollways and not traditional railways like the
| vehicles in the article.
| lbourdages wrote:
| Also the entirety of the Montreal Metro, which was inspired by
| the Paris Metro.
| NeoTar wrote:
| And Sapporo in Hokkaido.
| m463 wrote:
| also mexico city
|
| _Ten of the lines are rubber-tired. Instead of traditional
| steel wheels, they use pneumatic traction, which is quieter and
| rides smoother in Mexico City 's unstable soils. The system
| survived the 1985 Mexico City earthquake._
|
| https://en.wikipedia.org/wiki/Mexico_City_Metro
| ilamont wrote:
| So does Taipei's Wenhu line
| (https://en.wikipedia.org/wiki/Wenhu_line) which was built by a
| French consortium in the 90s (Matra IIRC). Construction
| disputes were epic but it seems to operate very smoothly now.
| The other lines in the system are rail-based.
| lqet wrote:
| AFAIK, basically all French subway systems opened after the
| 1960s use this system.
|
| This is one of the things I strongly associate with Paris: the
| slight smell of burned rubber when you enter a Metro station of
| a line with rubber tires.
|
| Pro tip for Paris visitors with children: ride with one of the
| automated lines 1, 4 or 14, and enter through the very first
| door. There is a fake (printed) control panel for children
| below the front window [0].
|
| [0] https://c8.alamy.com/comp/2GC1HTP/paris-automatische-
| metro-m...
| littlestymaar wrote:
| The reason why metros on tires is a thing is that they used
| to have much better acceleration/breaking characteristics
| than rails, which is good for metros since you can cram more
| trains in the same lines this way.
|
| I said "used to" because, from what I understood, the
| development of ABS made breaking characteristics of
| traditional trains much better than before, which reduces the
| improvement you get with tires.
|
| (Don't quote me on that though, I got this from a coffee
| machine discussion with a former metro driver when I was
| working for RATP 10 years ago so my memory may not be 100%
| accurate at this point)
| TylerE wrote:
| Half right. The limit at this point is much more do with
| what (likely standing, possibly not even holding on) people
| can tolerate, not what the device is physically capable of
| generating.
| littlestymaar wrote:
| True, though _emergency braking_ isn 't entirely subject
| to these limitations.
|
| At least for tramways I know for sure[1] that the tram
| will happily have you break your arm inside the tram
| because it braked too strong in case of emergency rather
| than crushing a pedestrian that crossed in front without
| paying attention.
|
| Maybe the rules are different for metros though, given
| that there aren't as many pedestrian on the way...
|
| [1] because I got the information from the system design
| team of a big tramway manufacturer I worked with no later
| than last year so my memory is much fresher, and the
| source is more reliable.
| inferiorhuman wrote:
| Muni reduced the emergency braking force back in
| 2008-2009 or so, because, yes people were getting injured
| (and given how frequent EB applications were back
| then...). You can definitely achieve sufficient braking
| without having to violently throw people to the ground.
| inferiorhuman wrote:
| Both BART and Muni had problems with the service brakes
| on their new trains flat spotting the wheels - apparently
| it's still not quite as much a solved problem as it
| should be. BART especially tends to run their trains with
| out of round wheels - almost certainly not helped by
| running aluminum wheels.
| almatabata wrote:
| Is it this system: https://en.wikipedia.org/wiki/Rubber-
| tyred_metro
|
| It mentions Paris Metro line 14.
| avidiax wrote:
| > a comparable carriage fitted with pneumatic tyres could need as
| many as 20 wheels.
|
| How does a bus get by with far fewer wheels?
|
| I think the answer is that they are still building with the same
| weight as a train, rather than a bus.
|
| That points out an unexplored engineering envelope for modern
| trains, made possible by newer technologies:
|
| * Very light trains. Think lighter than road cars, since they
| don't need crumple zones or crash worthiness.
|
| * Virtual coupling. Basically platooning on rails. Now the cars
| need to at most push/tow one other disabled car, so they don't
| need a beefy chassis to support towing long trains, coupling
| forces, etc.
|
| * Homogenous cars. They all have traction motors, small batteries
| and sensors and compute. Think a low-range Tesla on rails.
|
| * Autonomous control. Self-driving on rails. No operator cab.
| Since the train is now quite light, with a reasonable stopping
| distance, obstructions on the track can be potentially avoided so
| long as the sensors are adequate.
|
| * Much faster acceleration and deceleration. With leaning, they
| could also corner faster.
|
| * Probably intrinsically quieter, but now pneumatic tires would
| probably have reasonable life.
| alephxyz wrote:
| That's essentially a light rail system. Have a look at the
| Montreal REM.
| jltsiren wrote:
| > Very light trains. Think lighter than road cars, since they
| don't need crumple zones or crash worthiness.
|
| Crashes involving light rail are common in urban areas, because
| the trains share streets with cars. I don't see that going away
| as long as human-driven cars are allowed. And because
| passengers are often standing, the trains must be heavy to
| improve passenger safety in crash situations.
|
| > Virtual coupling. Basically platooning on rails.
|
| Modern designs typically have very long cars, with only 1, 2,
| or rarely 3 cars in a train. Longer cars increase passenger
| capacity and improve space utilization, because passengers can
| move around freely. They also allow busy passengers save some
| time by exiting from the right end of the train.
|
| > Much faster acceleration and deceleration. With leaning, they
| could also corner faster.
|
| Urban trains already limit acceleration and deceleration to
| improve passenger safety and comfort. Long-distance trains with
| sitting passengers and grade separation are another matter.
| badcppdev wrote:
| Train crash worthiness is quite an interesting topic. Important
| to remember is that trains carry hundreds of people. So a crash
| involving a single train carriage can easily become a
| catastrophe.
|
| https://www.youtube.com/watch?v=ewr-4TvG810
| xnx wrote:
| Excellent ideas. In the US, metropolitan rail transit systems
| need a dramatic reimagining. They are expensive, slow, and
| often crime ridden. Would love to see their right of way put to
| better use.
| Zone3513 wrote:
| We should rip out the train tracks, put down asphalt, and
| convert them to car tunnels, but to be used only by people
| driving one specific brand of car.
| mikepavone wrote:
| > I think the answer is that they are still building with the
| same weight as a train, rather than a bus.
|
| A non-trivial part of this difference is that train cars are
| generally bigger than a bus. Light rail is generally more bus
| sized and they are generally closer in weight (though still
| heavier).
|
| > * Homogenous cars. They all have traction motors
|
| Electric passenger rail systems generally already use EMUs
| which have a power unit per-car or per pair of cars.
|
| > small batteries
|
| I'm not sure how you're going to have a small battery in a bus-
| sized vehicle that needs to operate fairly continuously for a
| good portion of the day unless this is on a partially
| electrified ROW. EMUs with smaller batteries to serve such
| routes already exist FWIW.
|
| I think there's a reasonable case to be made to adjust US
| passenger rail regulations to allow lighter cars (especially in
| the context of high-speed rail), but allowing pneumatic tires
| seems like a poor motivation for it.
| netbioserror wrote:
| The author keeps asserting the "inherent weakness" of steel-on-
| steel railways; however, there are very good reasons it has been
| settled on as a good choice. Friction and sound losses are
| generally minimized, thanks to a very small contact surface and
| smooth, hard materials with little give; wheels can be re-
| machined back into spec a couple times rather than being
| replaced; rails can be re-used for lower-speed applications when
| worn; unlike pneumatic tires, steel can be machine into conical,
| self-centering, turn-adapting geometries with fixed axles and no
| need for differentials; the list continues and is quite long.
| Apparently, a recent change to wheel geometry reduced wear and
| extended lifetime by as much as 40%.
|
| See Practical Engineering's latest video:
| https://www.youtube.com/watch?v=Nteyw40i9So
| hyperthesis wrote:
| Feynman on the turn-adapting bit
| https://youtube.com/watch?v=y7h4OtFDnYE
| ianbicking wrote:
| Makes a lot of sense for freight... lots of weight, most miles
| going through lower population areas.
|
| Feels a little silly for relatively light humans being
| transported through high population areas.
| singleshot_ wrote:
| Check out people movers at large airports: they look like
| trains, run on their own tracks, but have tires.
| TylerE wrote:
| The humans may be light... the car around them built to
| survive a 100mph crash certainly isn't.
| user_7832 wrote:
| Sure but buses and cars themselves are strong enough and
| use rubber tyres. Not that I think rubber's a good idea for
| trains, but still.
| jjoonathan wrote:
| > Not just inefficient
|
| What? I thought wheel deformation was a huge source of drag and
| steel tires were one of the main reasons why trains were
| comparatively _efficient_.
| TylerE wrote:
| They are. This article is just...wrong.
| sreedhark wrote:
| I remember this thread from hn. Tire dust makes up the majority
| of ocean microplastics -
| https://news.ycombinator.com/item?id=37726539
|
| Link to the article - https://www.thedrive.com/news/tire-dust-
| makes-up-the-majorit...
| brazzy wrote:
| There was also a design with a layer of rubber between an inner
| steel wheel and a thin outer steel tire.
|
| That was used by high speed trains in Germany - until one of the
| steel tires broke at 300 kilometers per hour and got stuck in a
| switch, causing the train to detail and hit the support column of
| an overpass, which collapsed on top of the train. 101 people
| dead: https://en.wikipedia.org/wiki/Eschede_train_disaster
| Sharlin wrote:
| Jesus Christ. Talk about a catastrophic failure. And crazy
| unlucky to happen just before an overpass.
| TedDoesntTalk wrote:
| Crazy story. Thanks for sharing.
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(page generated 2023-10-03 23:00 UTC)