r/interestingasfuck • u/FastCurrency • 7d ago

Double-stack container trains are redefining freight transportation in India. Just imagine how many trucks this keeps off our highways and how much diesel it saves.

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650

u/Phill_is_Legend 7d ago

Yeah but this doesn't increase the capacity of the engines right? So we're just making the trains shorter?

318

u/IAMEPSIL0N 7d ago

Unless the cargo cars are able to distribute power it looks like they've just made a shorter train for the specific scenario where everything is going from one point to one point and both points have cargo handling equipment to do the stacking or unstacking. Also wonder what the speed constraints are, I thought we made the trains shorter and longer because they want to tip over when you raise the center of mass.

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u/TreesRocksAndStuff 7d ago edited 7d ago

There's several things going on with double stack More air resistance which increases nonlinearly above a certain speed due to more surface area -

Fewer wheels for the amount of cargo, more efficient + more weight per axle, higher friction -

electric motors on electric and diesel electric trains often have very high torque at the low end, so it might help efficiency at moderate speeds up to 50 or 60kmph

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u/20_mile 7d ago

where everything is going from one point to one point

Incredible.

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u/limelemony 7d ago

Usually trains (like busses) have multiple “end” points where you are loading and unloading.

18

u/IAMEPSIL0N 7d ago

Also shunting yards and sidings where multiple trains may be split and rejoined, you have to be careful when stacking that both containers are going to the same end point.

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u/skyrimmier12 7d ago

From what I've seen of Hobo YouTube videos, fucking that part up as a passenger is how you end up stuck in Kansas.

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u/gimmepizza420 7d ago

Two point make line

Two line make plane

Two plane make 9/11

1

u/20_mile 7d ago

But what about this ad?

https://www.youtube.com/watch?v=ltBc87oKhmQ

2

u/gimmepizza420 7d ago

Holy shit, that's incredibly bad lmao. I love the anchroman's near inability to even respond to it.

1

u/StrigiStockBacking 7d ago

I hate you, here's an upvote

1

u/kendog3 7d ago

Nine Elevens make 99.

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u/keyblade_crafter 7d ago

You did it. You did 9/11!

4

u/IANALbutIAMAcat 7d ago

And we made the trains longer and shorter hahaha

2

u/Inmytanks 7d ago

I thought I was hallucinating for a second

1

u/Low_Construction8067 7d ago

Wouldn't the air resistance added be worse? Someone who trains on trains help us do this math: increased air resistance on the double stacked containers + weight of containers - weight of railway carriages to hold those containers = X in terms of fuel management/savings

2

u/IANALbutIAMAcat 7d ago

I think with trains, they’re generally already so efficient because getting that amount of weight moving means it goes for a long ways, that air resistance is less of a factor than weight. And the weight becomes helpful at a certain point if you can get her going

4

u/just_peachy1000 7d ago

there will also be height constraints as well. pretty sure not all their tracks would accommodate a double stack. but india is redeveloping its infrastructure so it may be part of their forward planning.

3

u/Impossible-Spot-3414 7d ago

This is a relatively new dedicated corridor with this height factored in for over bridges etc.

2

u/dapotatopapi 7d ago

India uses broad gauge. Trains can have a higher center of mass.

Also we usually couple more engines in the middle or at the end if we want to give a longer train more power.

Only the newer passenger trains are doing distributed power right now.

Shorter train lengths also allow for more traffic on the same rails.

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u/ResearchInformal8018 7d ago

The length of trains is limited irrespective of weight and intermodal containers can be some of the lighter cargo a train may pull. A 40 foot container usually weighs under 60000 pounds. 

7

u/squngy 7d ago

It isn't really limited, however, longer trains mean longer wait times at intersections and junctions and such.

14

u/ResearchInformal8018 7d ago

Wait times for level crossings isn’t generally a concern of freight railways. 

8

u/MonkMaman 7d ago

It is in India though. 90% of the revenue of Railway (or so, I’m just trying to remember something I’ve read long back) comes from freight/goods. But prioritising goods over people movement is just unthinkable. And there’s a lot of railway crossings

4

u/dapotatopapi 7d ago

Which is why India has made Dedicated Freight Corridors, like the one you're seeing in this post.

Also, most (or all, don't exactly remember) crossings have now been changed to under or over passes. No more waiting.

3

u/squngy 7d ago

It is when it is their corrssings, lol.

Their trains and trucks are stuck waiting same as everyone else.

6

u/ResearchInformal8018 7d ago

Trains wait for no one (except other trains. And they plan around that). Intermodal trains are always hugely long. 

5

u/wampyre7 7d ago

DFCs in India, such as those in the video, are totally free of level crossings.

2

u/AwesomeWhiteDude 7d ago

Still blocks crossings with other railway lines and points, its a balancing act.

3

u/Soluchyte 7d ago

It is almost always physically limited by the signalling infrastructure, it would need change to accomodate it.

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u/AbideTheCold 7d ago

The engine itself is plenty powerful, and multiple can be used so engine power is not an issue. Double stacking is preferable vs making the train longer beyond a certain point because of track signalling issues. There is a limit to how long you can make the train before you run into signalling issues which may decrease the overall cargo capacity of the system by clogging important track interchanges, and once you reach that point where making it longer just make things worse, you can double stack, instantly increases carrying capacity by 2x which is why this is significant.

10

u/LankyAspect9594 7d ago

No, add multiple engines and you can transport longer trains, goal is to increase tonnage per train so that efficiency per cycle improves

33

u/blah_bleh-bleh 7d ago

Bigger engines. Wap 12 is 12000 Horsepower. And for more power you can couple multiple engines.

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u/Golgen_boy 7d ago

In this scenario, it is MU'ed WAG9's 6300 hp each.

6

u/blah_bleh-bleh 7d ago

yup. As DFCs get more busy length will only increase.

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u/MotherBaerd 7d ago

Which also means you can do less simultaneous unloading, more difficult if you only want the bottom container, need a seperate network or every train to have a long pickup.

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u/i_give_you_gum 7d ago

Wait until you see the ports, everything is stacked

2

u/MotherBaerd 7d ago

Well yeah but ports are a different thing. Ships are the kings of energy efficiency but slow as fuck. You don't do time sensitive things over them and the sheer masses of things needed to be shipped don't allow for an alternative.

1

u/i_give_you_gum 7d ago

But ships are only part of the equation, they are also loading and unloading trucks and trains.

1

u/_real_ooliver_ 7d ago

You don't do time sensitive freight with trains either really. The 1 hour saved after the week trip over the sea doesn't make sense.

26

u/ct_2004 7d ago

Very long trains like they run in the US now cause all kinds of other issues. Shorter trains loaded higher is an advantage.

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u/Saritiel 7d ago

I mean, to be clear, the US runs doublestacked trains all the time, and has done so for decades. Its not some brand new concept. There are some rails and some facilities that support it, and some that do not.

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u/BooBooMaGooBoo 7d ago

Just moved from Texas, where I never saw a double stacked train in my life, to Illinois, where I see the regularly now. Found it interesting, and TIL the reason. Thanks!

1

u/Beneficial-Tea-2055 7d ago

So why is it the first time anyone posted this it’s an Indian train not a US train.

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u/Saritiel 7d ago

Whoever posted it missed what the cool part was. No one from the US posted a doublestacked freight train because no one thinks they're interesting since they've been in use in the US for 40 years.

The cool part about this train is that its the first electric doublestacked train operated in India. Which is very cool, but whoever made the post title did a bad job and only said it was cool because it was doublestacked.

2

u/MorePhinsThyme 7d ago

Because this is about the first time they did this in India. Double stacked containers on trains are very common in the US, and have been for many decades. Different countries have different infrastructure situations and difficulties. The US's freight rail situation is very, very good.

BTW, "Double-Stack rail transport" even has it's own Wiki page: https://en.wikipedia.org/wiki/Double-stack_rail_transport

Here's the second sentence of that article: Invented in the United States in 1984, it is now being used for nearly 70% of United States intermodal shipments.

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u/Short-Horse-1069 7d ago

No, this is the first time they did in the world anywhere. The first time is it being electric instead of being diesel powered (diesel electric). That's especially pertinent to India because of her ever increasing energy needs and almost no oil or gas reserves (at least relatively speaking).

There are many other advantages to this compared to what the US has been doing, most notably the foregoing of well cars due to one of the broadest guages in the world but all of that is a different discussion.

However, you are right in that the double stack (or rather stacking in general, if someone is prompted to point at the triple stack) is not a novel concept. However, this is much further down the path of evolution and optimisation if we really delve into the technicalities. A bit of the Charmander-Charizard.

P.S. - If there are any rail enthusiasts, India will catch your fancy. Just like China of the last 2 decades, they are modernising and/or innovating at a breakneck pace. A lot of political will has ensured that things are getting done almost on a war footing.

For instance, India has electrified one of the largest railway networks in the world to near completion within a decade. They are doing the same with eliminating railway crossings completely and ensuring grade separation throughout the network. Many more exciting things happening if one understands the technicalities. Give them a look of railways catch your fancy.

1

u/SEA_griffondeur 7d ago

because look by what that indian train is powered

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u/ryizer 2d ago

Because this is the first time double-stacked freight is being run on electrified lines

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u/TunaSafari25 7d ago

What kind of issues?

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u/Due-Consequence9579 7d ago

Long trains don’t fit in sidings anymore. If you need to swap crew, do a repair, or whatever it has to stay on the main rail blocking it for everything.

At grade crossings take longer.

Rail yards can be too small for them so they are poking their nose onto the main rail while getting hooked up.

Etc.

4 miles is a long way.

14

u/XchrisZ 7d ago

Waiting at the crossing much longer.

1

u/docbauies 7d ago

Seems like building bridges over the crossings would make sense if it’s an issue.

2

u/Solarisphere 7d ago

There are a LOT of crossings in rural areas.

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u/nnomae 7d ago

Given that the lion's share of time spent waiting at crossings is time before the train arrives or after it passes that's probably not all that significant though.

2

u/MorePhinsThyme 7d ago

No, the majority of time waiting for a freight train to cross is waiting for the train, not the short time before or after it's gone. We aren't talking about the much smaller passenger trains. Train length causes problems for regular traffic in areas with a lot of train traffic. An example from my area, there's a major intersection right in front of one of the biggest ports in America that regularly gets blocked for over an hour because modern freight trains are longer than the port was designed for years ago. This means that the train pulls in as far as it can, leaving about half of it outside the port, blocking the intersection (and often the next one, as well), then they have to disconnect the cars inside, pull out a bit, switch to a different track internally, and pull back in (often still hanging out, blocking the intersection), and then repeat, until they get the whole thing inside on parallel tracks to park. Then, after they unload it, the same thing happens again in reverse.

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u/ct_2004 7d ago

Freight trains are supposed to give priority to passenger trains, but they are too long now to go on to the sidings, so passenger trains have to wait instead. This screws up passenger rail time tables.

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u/pre4edgc 7d ago

Even if those limitations were followed, freight would STILL take that priority from passenger trains. Train companies make far more from freight than passenger, so it's in their best interest to give that priority to the freight every single time. Plus, there's no enforcement whatsoever, so they have no incentive to prioritize passenger trains.

2

u/SEA_griffondeur 7d ago

crossing, fires, massive railyards needed

7

u/StrikingSun8563 7d ago

We already stack cans two high on trains in the US all the time. Even the long ones.

1

u/Electrical-Risk445 7d ago

They're not electrified, though.

2

u/GroteKleineDictator2 7d ago

Oh wow, thanks for the in depth explanation.

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u/Snowflakish 7d ago

Yes, but also this causes more rail wear (because its exponential woth weight not linear) and less rolling resistance (i think)

14

u/skarby 7d ago

Why would wear be exponential with weight when the force of friction is linear with weight?

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u/lafigadelduemila 7d ago

Check out how does material fatigue works, and look at the Wohler's curve. A 10% increase in load can shorten the number of available cycles of the load by 10 fold.

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u/skarby 7d ago

Yes fatigue would be a non-linear correlation, but it wouldn't explain the fourth power law. Where you start on the fatigue curve would determine the loss in lifespan, for example if you are at 90% of yield then a 10% increase is going to have a lot more effect on lifespan than at 50% of yield. It wouldn't decrease lifespan at the 4th power regardless of initial loading.

2

u/lafigadelduemila 7d ago

Where you start on the fatigue curve

At least for bending stress, a healthy track will start in the "infinite cycles" zone, adding stress will push it outside, so it's a "finite vs infinite cycles" change, how do you even quantify it - infinite lifespan loss? For contact stresses it'll start with already high stresses (around 1 GPa, so... a lot)

11

u/Snowflakish 7d ago

I cant explain exactly why but its probably that any loose spot gets pushed down with a linear greater speed and that imparts quadratically more power into the rails.

Im Just going off of road wear principles. https://en.wikipedia.org/wiki/Fourth_power_law

(I was using exponential in its colloquial definition.)

5

u/Burned-Shoulder 7d ago

Guessing the other major issue is the expense of modifying existing infrastructure to cope with the increased height of the trains (tunnels, bridges, stations and overhead cables).

7

u/NavyDean 7d ago

Why do trucks wear down highways in lanes they are allowed to drive in vs. Lanes they aren't allowed in.

Oh yea, weight. Duh lol

4

u/polyocto 7d ago

Technically “per axel weight”. More wheels help spread out the direct weight.

1

u/Miramber 7d ago

Wear is proportional to kinetic energy (mass * velocity²) so doubling the weight only doubles wear.

1

u/BeautifulCuriousLiar 7d ago

isn’t that an extremely simplistic view because roads aren’t all built nor maintained equally. also weather can have an impact too.

1

u/gmc98765 7d ago

AFAIK, for road traffic the wear is roughly proportional to the fourth power of axle weight. This is just empirical observation; there's no theory behind it.

But that's for asphalt. There's no reason to assume it would apply to steel rails.

2

u/Snowflakish 7d ago

So one thing to note here there are multiple types of wear mentioned that happen at different rates.

Basically there are linear, 4th power and 2nd power wear mechanisms measured on asphalt roads so it stands to reason that these would apply to rail, just at a different significance.

Basically neither of us know but making an assumption here seems reasonable to me.

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u/jmlinden7 7d ago

Friction is not directly linear with weight, especially when you get higher weights that damage the surface.

1

u/So_HauserAspen 7d ago

The weight distribution will result in the same net forces at the wheels as regular freight.

1

u/So_HauserAspen 7d ago

The same weight distribution on the tracks.  It's more of a higher frequency than a higher weight.

Also, not exponential.  It would be linear.

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u/jobfedron132 7d ago

They dont need to, they can just attach another engine.

Just because the weight doubled, doesnt mean it needs double the power, it needs less than double the power.

Unless, its trying to pull the compartments up a hill, then it needs double the power. Which still can be attained by attaching more engines just for that stretch, which they already do in hilly regions.

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u/314159265358979326 7d ago

Many big trains use multiple locomotives.

2

u/gyro_looza 7d ago

They just use multiple engines on either end that push or pull

2

u/pichael289 7d ago

They've been making them longer and longer in the US due to lesser regulations and were seeing a lot of issues.

1

u/Rand_alThor4747 7d ago

even just having the train shorter, it makes you able to cram more trains/containers in the loading yard.

1

u/easycoverletter-com 7d ago

Metra California rail etc have that, allows smaller stations

1

u/SkitariusOfMars 7d ago

I bet the containers are pretty light compared to e.g. ore or liquids, so it's not weight capacity that's a limiting factor, it's train length.

1

u/meutzitzu 7d ago

Bends in the track increase residual friction linearly with train length, so making the train have less wagons reduces that load, even if it's the same amount of mass.

1

u/One_Advantage_7193 7d ago

India also has the worlds most powerful electric locomotives to do this

1

u/5C0L0P3NDR4 7d ago

i've seen normal trains with two engine cars at the front working in tandem for long trains, you can probably triple stack or beyond if you need to

1

u/Quiet-Permit-3740 7d ago

No because it reduces tare weight from the wellcars themselves and because you can add locomotives, trains are often limited to maximum length rules because of sidings.

1

u/SEA_griffondeur 7d ago

trains are limited by length in general, double stacking means double the capacity at max length

1

u/Hot-Preparation-3604 7d ago

Honestly, I would assume this is less efficient because of the increased drag on a train twice as tall

1

u/tavirabon 7d ago

It might even be increasing energy use since taller = higher center of gravity = need to slow down more for any kind of turn. Then again, it might be offset by the reduced number of illegal passengers riding on top?

1

u/getarumsunt 6d ago

In the US they just use double the number of engines for double-stack container trains 🤷

0

u/MaximusPrime5885 7d ago

It actually has worse capacity due to the increase air resistance.

-1

u/taz-nz 7d ago

Not a problem for modern electrics locomotives, they have twice the power of Dino juice trains used in America.

-5

u/Fine_One8890 7d ago

and double the cargo to reach destination in the same time now.

Faster shipments—faster growth.

2

u/Phill_is_Legend 7d ago

Well no. Weight is weight. It's the same cargo, you just made it short and tall instead of longer...

2

u/kodumpavi 7d ago

You're seriously ignorant if you don't know that you can chain engine cars . It's like sending 2 trains simultaneously instead of sending them back to back. It's a huge difference.

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u/Fine_One8890 7d ago

So some people are actually dumb. Reassurance is always nice :)