[HN Gopher] The short-lived experiment with rubber tires on rail... ___________________________________________________________________ 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. ___________________________________________________________________ (page generated 2023-10-03 23:00 UTC)