13
$\begingroup$

A question that arose from here.

Say we have a planet with a different percentage of various elements than Earth, but steam train technology, and we were striving for train track longevity. Is there any metal/ceramic/alloy/layering system that could provide a similar experience as standard steel, but last for longer?

$\endgroup$
3
  • $\begingroup$ Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on Worldbuilding Meta, or in Worldbuilding Chat. Comments continuing discussion may be removed. $\endgroup$
    – L.Dutch
    Commented Nov 1, 2023 at 21:52
  • 2
    $\begingroup$ can we use different train technologies? hover trains, for example, should generate very little wear on the track, I assume? Maglevs, too $\endgroup$
    – njzk2
    Commented Nov 1, 2023 at 22:09
  • 1
    $\begingroup$ @njzk2 I expect the Maglevs to wear down the track around where they get up to speed/stop. Or any place they will need to slow down to below 150km/h. I guess it would still be less effort to maintain if the track is long enough, at least for the wear-and-tear parts. It would bring with it a whole new set of challenges, but with cheaper metal costs because of abundance and a very large budged, halving traveling times seems worth it. And the technology is exists. $\endgroup$
    – vinzzz001
    Commented Nov 22, 2023 at 10:06

6 Answers 6

26
$\begingroup$

10% Gold 90% Platinum

I know, it surprised me too. Its the most wear resistant metal alloy known.

To quote

tires made from it would only lose a single layer of atoms after a mile of constant skidding

It responds to heating differently than most alloys hardening it on the nanoscale because the grain structure does not change under heat or stress once set. This material vastly outperforms any other known metal alloy for wear resistance. It turns out hardness is not the best predictor of wear resistance but how materials react to friction heating. Matching sapphire and diamond for non-metals without their extreme brittleness. As a side benefit it is also extremally resistant to corrosion.

It will need to be wider and more solidly built than current rails due to lower overall strength but you might need that anyway. It also have very very low friction which is bad for train tracks, train tracks need decent friction for the wheels to grip the rails. So if you use it you need to increase grip possibly by changing the contact shape or some other method that might make a good follow up question.

Another option is to make the rails of something else and coat it with this alloy.

As a side benefit it is an very good electric conductor so you could have electrically powered rails.

A great idea from a commenter below, cog assisted railways did exist, Called rack railway they had a cog toothed track along side the normal rail anywhere the train had to climb, places were friction might not be enough to grip the rails. a toothed cog on the axle would pull the train along no matter the grade.

https://onlinelibrary.wiley.com/doi/full/10.1002/adma.201802026

https://www.materialstoday.com/metals-alloys/news/new-platinumgold-alloy-most-wearresistant/

$\endgroup$
17
  • 6
    $\begingroup$ Aren't these metals soft? $\endgroup$ Commented Nov 1, 2023 at 7:02
  • 4
    $\begingroup$ @KevinKostlan Depends on how you measure hardness and what you’re comparing to. Platinum is not as hard as hardened steel by most measures, but it’s actually far harder than mild steels by many measures, and it makes hardened aluminum look like a joke. The thing is though, hardness is not the same as wear resistance. Super-hard materials are often not exceptionally wear-resistant when the contact surface is the same material. $\endgroup$ Commented Nov 1, 2023 at 11:20
  • 3
    $\begingroup$ @Demigan low rolling resistance is the benefit, low friction comes from that, but they need some friction to start and stop $\endgroup$
    – Chris H
    Commented Nov 1, 2023 at 16:32
  • 7
    $\begingroup$ Wear resistance doesn't seem to be especially useful for rails. They don't get worn down by wear, they get literally bent out of shape by the compression forces of the passing train, and need to get re-ground into shape. (Which, incidentally, would be more difficult with a wear-resistant alloy.) $\endgroup$
    – Cadence
    Commented Nov 1, 2023 at 16:33
  • 4
    $\begingroup$ @Cadence rails absolutely get worn out, to the point trains constantly monitor it. wear is the primary reason rails need to be replaced. researchgate.net/figure/… $\endgroup$
    – John
    Commented Nov 1, 2023 at 20:46
19
$\begingroup$

So, we can look at the real world to see what goes into a tracks longevity. As expected, there is no easy answer.

According to this your standard gravel bed might last 15 years, despite the tracks in theory being in for up to 100 years. If you use concrete and steel elements the entire thing might last 30.

Of course, "last" is somewhat of a relative term. These figures, probably, assume for instance someone is there to remove plants.

enter image description here

This will not last 30 years.

And this is not really an issue you can just engineer away. Even if you elevate the entire track on a concrete wall, like this;

enter image description here

Dirt, Water and Seeds will get up there and will start to deteriorate the track. That being said, elevating the entire track will improve its longevity because it just takes longer for dirt and stuff to accumulate.

Note, that i have not even touched on using other metals. Because the actual physical rail isnt what is going to break first. Its the sleepers, ballasts and other parts which will fail first and make the entire track unusable. You can live with the rail warping a bit. You positively cannot live with the sleepers being eaten up by worms.

So, Imo, the main thing you would want to do is elevate the track a couple of meters perhaps with a base shape that prevents anything from growing up easily. You then want to make sure the top of your elevation structure is build so rain does not accumulate and can flush out dirt. Since you are already using approximately all the concrete in the world the sleepers are obviously out of it as well. And then make the rails stainless so they dont rust away.

Provided there is no earthquake or major change in the local geography that wall with a track on it should be usable for quiet a long time.

$\endgroup$
7
  • $\begingroup$ Couldn't you raise the tracks on the 'steel' supports, high enough that nothing can easily grow into it? And you could use the same to make a whole tunnel, if money is no objection. $\endgroup$
    – Trioxidane
    Commented Nov 1, 2023 at 9:01
  • 4
    $\begingroup$ You don't build a massive concrete wall, you just build what is essentially a bridge with pillars every couple of meters. This is actually done in various places in the real world. $\endgroup$
    – quarague
    Commented Nov 1, 2023 at 10:37
  • $\begingroup$ @quarague yeah but a concrete wall is cooler D: $\endgroup$
    – ErikHall
    Commented Nov 1, 2023 at 10:38
  • $\begingroup$ So the solution is MORE steel? MUCH MORE steel, like building not only the track but also the the sleepers, the bed and everything out of one solid piece of metal? ;) $\endgroup$
    – LazyLizard
    Commented Nov 2, 2023 at 14:57
  • 1
    $\begingroup$ @LazyLizard, no, because then you need to deal with thermal expansion. $\endgroup$
    – Mark
    Commented Nov 2, 2023 at 20:42
12
$\begingroup$

Water.

But, to be fair, you would have to replace the trains, too.


If money is no impediment, an artificially built, fast-running water channel can be used to transport massive amounts of load with minimum to no downtime. You just place stuff on a special cargo boat on the fast-track river, and someone down the line will pull it off from it by means of diverging the flow temporarily to an unloading area.

Your cargo wouldn't need an engine to carry them, as the power would be provided by the water.

With the proper engineering, this system also doubles as an irrigation system for the huge swat of land it can cross, enabling once unproductive land to be used for crops and animals.

By clever diverting some of this waterflow, you could use waterwheels to provide power to small devices or maintenance stations, or for ligthning up the Great Waterway.

While this system wouldn't be faster than a single train on a railroad, using water enables you to move far larger loads, way more often. Your "cargo bandwitdh" ends up being higher, even if an individual piece of cargo takes longer to send.

Canals are awesome.

$\endgroup$
3
  • $\begingroup$ Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on Worldbuilding Meta, or in Worldbuilding Chat. Comments continuing discussion may be removed. $\endgroup$
    – L.Dutch
    Commented Nov 3, 2023 at 4:00
  • 1
    $\begingroup$ -1 For not reading the (very short) question. OP isn't ignoring cost of metal because they have infinite money, they're assuming metals on some fictional planet are more abundant. This does not answer any part of the actual question $\endgroup$
    – automaton
    Commented Nov 3, 2023 at 16:58
  • $\begingroup$ @automaton I did read the question, and I did read the comments. The goal of the OP is to find a way for the protagonists to find a "track" hundreds of years in the future. Canals fit this description. $\endgroup$
    – Mermaker
    Commented Nov 3, 2023 at 22:47
8
$\begingroup$

Aluminum bronze. Basically nearly corrosion proof mild steel. Can't be hardened but it is a bearing surface so just use more of it to support the load if cost is no object. I've heard it is difficult to machine but I've found it among the easiest materials to machine. But the kind I've experienced does not contain nickel. I think the nickel containing kinds are a bit stronger and more corrosion resistant, though.

Hopefully it's a case where the material is cheap EVERYWHERE, rather than "expensive but cost is no object" in the railway project. Otherwise the rails will get stolen in the blink of an eye. Such a world would see a very great many consumer items that use stainless steel, and industrial applications that commonly use mild steels replaced with aluminum bronze. Basically the Bronze Age taken farther into the future since copper stays cheap and abundant and there was not nearly as much motivation to force iron to work.

$\endgroup$
3
  • 3
    $\begingroup$ Even steel railroad track gets stolen sometimes: bbc.com/news/blogs-news-from-elsewhere-28311240 $\endgroup$ Commented Oct 31, 2023 at 17:22
  • 1
    $\begingroup$ Might be because the Nickel forms Nickel-Alumide which is an odd alloy that actually gets stronger as it heats up (up to a point) which probably makes it behave like it's being work hardened as you try and cut it (it gets used for the hot rollers at some steel mills) $\endgroup$
    – Samwise
    Commented Oct 31, 2023 at 22:16
  • 6
    $\begingroup$ This answer seems to assume that corrosion resistance is a central factor for rail tracks... This doesn't seem very obvious to me, essentially all tracks I have ever seen were quite rusted except for the actual bearing surface which is kept clean by the frequent friction. All these rails did their job just fine being a little rusty. $\endgroup$
    – fgysin
    Commented Nov 1, 2023 at 12:32
5
$\begingroup$

If money is no object / the distribution of elements is different (making it more common, perhaps?) tungsten could do the trick. It only begins to oxidize at extreme heats, and is already used in the real world as an improvement over steel in applications such as drill bits / cutting tools - it's more brittle than steel though, which is why it's usually layered over steel to support it.

It's not a different track material, but in David Brin's "The Practice Effect" they use a frictionless lubricant which increases the efficiency of rail travel and reduces the wear on the tracks to basically zero, which would improve the lifespan of your tracks. If memory serves the tracks there were a slightly guttered design, otherwise the lubricant would flow off the tracks and onto the ground.

$\endgroup$
7
  • 5
    $\begingroup$ zero friction would also mean your train can't move, trains need friction on the wheels to generate forward thrust otherwise the wheels just spin in place. $\endgroup$
    – John
    Commented Oct 31, 2023 at 21:19
  • $\begingroup$ God that'd be a PITA to fabricate lol. It's difficult to weld and must welded in an inert atmosphere and no material has a high enough melting temperature to contain it to smelt it. So you need massive liquid cooled crucibles to smelt the massive rails. Then there's issues with welding it. $\endgroup$
    – DKNguyen
    Commented Oct 31, 2023 at 21:26
  • 1
    $\begingroup$ I haven't read the book in ages, so I don't remember what the method was they used there, but with no friction you wouldn't need something with grip at the bottom, so much as something that provides forward thrust, and with aerodynamics that use wind resistance to keep it pushed down onto the tracks. As far as it being a pain to fabricate, no argument there. It's doable, though, with money not being an object. $\endgroup$ Commented Oct 31, 2023 at 22:15
  • $\begingroup$ @John anything would prevent such a train to use sails or thrusters? Or even simpler, just push it out of the station. let it slide and catch it at the next stop. $\endgroup$
    – spectras
    Commented Nov 3, 2023 at 3:52
  • $\begingroup$ @DKNguyen I know field repairs on train tracks are sometimes done using thermite to produce both the heat and the molten metal required... I wonder if you could make a tungsten thermite that would be energetic enough to weld tungsten in place. $\endgroup$
    – Hearth
    Commented Nov 3, 2023 at 15:19
1
$\begingroup$

You can look up toughest known material, which is a CrCoNi alloy. About 5 times tougher tan steel. However it was so far only created in the lab under special conditions, it's not clear whether it's possible to make rails out of it.

$\endgroup$
5
  • 1
    $\begingroup$ Is strength the only quality that rails need? I'd figure they'd need a little flex/lack of rigidity to avoid problems. $\endgroup$
    – Carduus
    Commented Oct 31, 2023 at 18:20
  • $\begingroup$ @Carduus When money is no object you just use even more material so that it doesn't flex as much! $\endgroup$
    – DKNguyen
    Commented Oct 31, 2023 at 18:53
  • 2
    $\begingroup$ @DKNguyen it needs to flex though, both to dampen vibration and to deal with thermal expansion. $\endgroup$ Commented Nov 1, 2023 at 13:09
  • 8
    $\begingroup$ An ideal answer might go into a bit more detail than "you can look it up" $\endgroup$
    – Aaron F
    Commented Nov 1, 2023 at 13:52
  • $\begingroup$ You're right sorry I had no idea what else to write. Toughness is important because it's about energy the material can sustain before breaking. That is directly related to longevity and allows bigger loads. It is different both from mere strength and from hardness. $\endgroup$
    – Juraj
    Commented Nov 3, 2023 at 16:25

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .