The short-lived experiment with rubber tires on railways (2013)

https://www.ianvisits.co.uk/articles/the-short-lived-experiment-with-rubber-tires-on-railways-9831/

by montalbano • 3 years ago

30 49 3 years ago

ianvisits.co.uk

jjgreen• 3 years ago

Still in use on a few lines of the Paris Métro

almatabata• 3 years ago

Is it this system: https://en.wikipedia.org/wiki/Rubber-tyred_metro

It mentions Paris Metro line 14.

lbourdages• 3 years ago

Also the entirety of the Montreal Metro, which was inspired by the Paris Metro.

NeoTar• 3 years ago

And Sapporo in Hokkaido.

ilamont• 3 years ago

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.

lqet2• 3 years ago

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 Métro 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...

littlestymaar2• 3 years ago

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)

azdle• 3 years ago

As far as I can find, the Paris Métro's rubber tire lines all run on special rollways and not traditional railways like the vehicles in the article.

m463• 3 years ago

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

brazzy• 3 years ago

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• 3 years ago

Jesus Christ. Talk about a catastrophic failure. And crazy unlucky to happen just before an overpass.

TedDoesntTalk• 3 years ago

Crazy story. Thanks for sharing.

Eddy_Viscosity2• 3 years ago

I heard that in this story the managers took a ride on train at high speed and wanted it to be smoother/quieter and that these wheels with rubber would do that, but the engineers said it was a bad idea but were overruled - at least until the tragedy.

There was a documentary about it but I can't find the link.

netbioserror• 3 years ago

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

ianbicking2• 3 years ago

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_• 3 years ago

Check out people movers at large airports: they look like trains, run on their own tracks, but have tires.

TylerE5• 3 years ago

The humans may be light... the car around them built to survive a 100mph crash certainly isn't.

hyperthesis• 3 years ago

Feynman on the turn-adapting bit https://youtube.com/watch?v=y7h4OtFDnYE

jjoonathan• 3 years ago

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.

TylerE5• 3 years ago

They are. This article is just...wrong.

avidiax2• 3 years ago

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.

xnx2• 3 years ago

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• 3 years ago

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.

alephxyz• 3 years ago

That's essentially a light rail system. Have a look at the Montreal REM.

badcppdev• 3 years ago

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

mikepavone2• 3 years ago

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.

inferiorhuman4• 3 years ago

  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).

Muni's articulated streetcars weigh about 100,000 lbs each while typically the max weight for a laden tractor trailer is around 80,000 lbs. Light rail is a marketing term, not indicative of the actual weight.

jltsiren• 3 years ago

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.

avidiax2• 3 years ago

Crashes involving light rail are common in urban areas,

That's a good point. That doesn't mean that trains need to be as heavy as they are, though. Having a crumple zone and weighing 3x of non-commercial road vehicles would still be quite a bit lighter, and would provide safety.

Modern designs typically have very long cars

I live in Switzerland, and it's common to have train combinations that are very long here, even with long cars.

limit acceleration and deceleration

There are limits, of course, but they can be relatively high if you strictly control "jerk". That's where computer control comes into play, as it requires high driver skill to stop the train at the right position while limiting jerk.

https://en.wikipedia.org/wiki/Jerk_(physics)

TylerE5• 3 years ago

That's been tried.

It did no go well, and was hated by both crews and the public. Rode extremely rough because it turns out it's a very different optimization needed.

https://en.wikipedia.org/wiki/Pacer_(British_Rail)#Analysis

sreedhark• 3 years ago

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...

somat• 3 years ago

The fun experiment was the paper wheels.

https://en.wikipedia.org/wiki/Paper_car_wheel

woodpanel2• 3 years ago

Can somebody explain to me the difference between this „short lived experience“ and the actual ongoing decades long operations of tire based metro/subway systems?

https://en.m.wikipedia.org/wiki/Rubber-tyred_metro

andbberger2• 3 years ago

michelin, apocryphally

paulkrush• 3 years ago

I second your request. I am guessing for starters that the article is taking about rubber on steel rails and your link is rubber tire metros.

superchroma• 3 years ago

Japan has a train-on-tires on an elevated overpass track around Tokyo bay.

It's pretty neat.

The short-lived experiment with rubber tires on railways (2013)

Related Stories