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HOI4 Dev Diary - Traiiiiins

Greetings, and welcome back for our last look at the supply system that ships with the Barbarossa update. As you all know, I’m British, and in Britain the trains never run on time - I couldn’t possibly break with this tradition, hence a completely intentional 10 minute delay on today’s diary.

There’ve been a couple of changes since we last looked at this, so you may find I’ll be reiterating a few aspects that we’ve already covered in previous diaries, albeit in some cases with a new twist.

Trains

As indicated in a previous diary, the logistics network that supplies your troops relies on the large-scale relocation of supply using trucks and trains.

Whereas trucks serve as an optional last-mile carrier for military supplies, trains make up the backbone of any logistics network that supplies an army which exceeds the local state supply available in its location.

The domestic production of trains is something that is unlocked via the technology tree. Many countries will start with the initial (civilian) train technology readily unlocked, however, there are several more options available to you as time progresses (more on this below!).

0.png


Your overall train need for the logistics network is derived from the overall supply usage of the nodes supplying your troops, and the distance factor that supply has to travel in order to reach them. In essence, the more troops you have drawing supply, the more trains you will need to keep supply running.

Needless to say, if fewer trains are provided than are required, supply output at point of demand will incur penalties proportional to the magnitude of the shortfall.

In one of our previous diaries, we alluded to a number of interactions that could be performed on supply nodes - one of these was a train priority setting. It transpired that this did not fit well with the underlying simulation, and we’ve removed this setting from nodes.

Logistics Strike

Of course, a freight-train loaded with supply makes a juicy target for the enemy. In NSB, CAS and bombers are able to perform the new logistics strike mission, which can put a severe strain on an enemy’s ability to supply their network - actively destroying trains and trucks, as well as damaging railways in the target area.

The strategic bombing air mission will also target rail and supply infrastructure, however the logistics strike mission is a much more effective way of neutralizing an enemy’s fighting capabilities while retaining important industrial infrastructure if you intend to occupy an area for any period of time.


1.png


Train Variants

As mentioned above, trains will be a researchable technology with several variants. Trains, unlike regular units, are not controllable - their movement and behaviour is entirely simulated based on the needs of your logistics flow. This said, there are several important statistical aspects to them.

2.png


To begin with, most of your network is likely to be populated by civilian trains. You can construct more of these by co-opting military factories. Further on in your campaign, you can unlock a variant of the civilian train with a significantly reduced construction cost.

To combat the strategic mission mentioned above, there is one (or..is it more?) further item in your toolbox for owners of the NSB expansion. Armored trains, while coming with a higher price tag, are much more resistant to destruction from air missions, and can act as an effective deterrent against logistics disruption.

Train enthusiasts (we have none of those here, right?) will note that the trains displayed above belong to the soviet union - there is indeed unique art as well as 3d models for several other major nations.

3.png


4.png


5.png


6.png

A highly camouflaged train in action.

7.png

Displayed trains are based on your stockpiled train equipment. This is the german armoured locomotive!

That’s all from me for today - I’ll hand over here to @YaBoy_Bobby to go over some of the details on supply distribution at a hub level:

Hub to Province Supply Distribution

We have talked about how trains and rails feed the supply hubs, but not so much about how hubs feed divisions in the field. As hubs are fed from the capital province by a rail network, divisions are fed by hubs over land.

Every Hub has an overland range that gives it a collection of provinces that it touches. This range is constant, but the cost of moving over each province is impacted by things like weather, terrain, rivers, and infrastructure. Motorization decreases the penalty for crossing each province, thus increasing the number of provinces a hub will touch and potentially creating greater hub density and thus greater overall supply in an area.

8.png


As has been alluded to with the phrase “hub density,” a province may be touched by multiple hubs. When multiple hubs touch a province, a ratio is created to determine what percentage of the supply requested each hub is responsible for. Every hub that touches a province lessens the supply burden of other hubs also touching the province.

In the final step, Divisions draw supply from hubs, depending upon the relationship between their current province and the hubs that touch that province. When a hub does not have enough supply to meet demands, the lack of supply is distributed evenly across all divisions currently drawing from the hub.

In older DDs we talked about a penalty to the amount of supply delivered to a province based upon weather, terrain, and distance. Over the summer we decided to remove this penalty as we found it compounded in a hard to predict way that created bad supply and sometimes penalized having more hubs touching a province in a way that we did not like.
 
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Greetings, and welcome back for our last look at the supply system that ships with the Barbarossa update. As you all know, I’m British, and in Britain the trains never run on time - I couldn’t possibly break with this tradition, hence a completely intentional 10 minute delay on today’s diary.

There’ve been a couple of changes since we last looked at this, so you may find I’ll be reiterating a few aspects that we’ve already covered in previous diaries, albeit in some cases with a new twist.

Trains

As indicated in a previous diary, the logistics network that supplies your troops relies on the large-scale relocation of supply using trucks and trains.

Whereas trucks serve as an optional last-mile carrier for military supplies, trains make up the backbone of any logistics network that supplies an army which exceeds the local state supply available in its location.

The domestic production of trains is something that is unlocked via the technology tree. Many countries will start with the initial (civilian) train technology readily unlocked, however, there are several more options available to you as time progresses (more on this below!).

View attachment 752460

Your overall train need for the logistics network is derived from the overall supply usage of the nodes supplying your troops, and the distance factor that supply has to travel in order to reach them. In essence, the more troops you have drawing supply, the more trains you will need to keep supply running.

Needless to say, if fewer trains are provided than are required, supply output at point of demand will incur penalties proportional to the magnitude of the shortfall.

In one of our previous diaries, we alluded to a number of interactions that could be performed on supply nodes - one of these was a train priority setting. It transpired that this did not fit well with the underlying simulation, and we’ve removed this setting from nodes.

Logistics Strike

Of course, a freight-train loaded with supply makes a juicy target for the enemy. In NSB, CAS and bombers are able to perform the new logistics strike mission, which can put a severe strain on an enemy’s ability to supply their network - actively destroying trains and trucks, as well as damaging railways in the target area.

The strategic bombing air mission will also target rail and supply infrastructure, however the logistics strike mission is a much more effective way of neutralizing an enemy’s fighting capabilities while retaining important industrial infrastructure if you intend to occupy an area for any period of time.


View attachment 752461

Train Variants

As mentioned above, trains will be a researchable technology with several variants. Trains, unlike regular units, are not controllable - their movement and behaviour is entirely simulated based on the needs of your logistics flow. This said, there are several important statistical aspects to them.

View attachment 752462

To begin with, most of your network is likely to be populated by civilian trains. You can construct more of these by co-opting military factories. Further on in your campaign, you can unlock a variant of the civilian train with a significantly reduced construction cost.

To combat the strategic mission mentioned above, there is one (or..is it more?) further item in your toolbox for owners of the NSB expansion. Armored trains, while coming with a higher price tag, are much more resistant to destruction from air missions, and can act as an effective deterrent against logistics disruption.

Train enthusiasts (we have none of those here, right?) will note that the trains displayed above belong to the soviet union - there is indeed unique art as well as 3d models for several other major nations.

View attachment 752463

View attachment 752464

View attachment 752465

View attachment 752466
A highly camouflaged train in action.

View attachment 752467
Displayed trains are based on your stockpiled train equipment. This is the german armoured locomotive!

That’s all from me for today - I’ll hand over here to @YaBoy_Bobby to go over some of the details on supply distribution at a hub level:

Hub to Province Supply Distribution

We have talked about how trains and rails feed the supply hubs, but not so much about how hubs feed divisions in the field. As hubs are fed from the capital province by a rail network, divisions are fed by hubs over land.

Every Hub has an overland range that gives it a collection of provinces that it touches. This range is constant, but the cost of moving over each province is impacted by things like weather, terrain, rivers, and infrastructure. Motorization decreases the penalty for crossing each province, thus increasing the number of provinces a hub will touch and potentially creating greater hub density and thus greater overall supply in an area.

View attachment 752468

As has been alluded to with the phrase “hub density,” a province may be touched by multiple hubs. When multiple hubs touch a province, a ratio is created to determine what percentage of the supply requested each hub is responsible for. Every hub that touches a province lessens the supply burden of other hubs also touching the province.

In the final step, Divisions draw supply from hubs, depending upon the relationship between their current province and the hubs that touch that province. When a hub does not have enough supply to meet demands, the lack of supply is distributed evenly across all divisions currently drawing from the hub.

In older DDs we talked about a penalty to the amount of supply delivered to a province based upon weather, terrain, and distance. Over the summer we decided to remove this penalty as we found it compounded in a hard to predict way that created bad supply and sometimes penalized having more hubs touching a province in a way that we did not like.
Greetings, and welcome back for our last look at the supply system that ships with the Barbarossa update. As you all know, I’m British, and in Britain the trains never run on time - I couldn’t possibly break with this tradition, hence a completely intentional 10 minute delay on today’s diary.

There’ve been a couple of changes since we last looked at this, so you may find I’ll be reiterating a few aspects that we’ve already covered in previous diaries, albeit in some cases with a new twist.

Trains

As indicated in a previous diary, the logistics network that supplies your troops relies on the large-scale relocation of supply using trucks and trains.

Whereas trucks serve as an optional last-mile carrier for military supplies, trains make up the backbone of any logistics network that supplies an army which exceeds the local state supply available in its location.

The domestic production of trains is something that is unlocked via the technology tree. Many countries will start with the initial (civilian) train technology readily unlocked, however, there are several more options available to you as time progresses (more on this below!).

View attachment 752460

Your overall train need for the logistics network is derived from the overall supply usage of the nodes supplying your troops, and the distance factor that supply has to travel in order to reach them. In essence, the more troops you have drawing supply, the more trains you will need to keep supply running.

Needless to say, if fewer trains are provided than are required, supply output at point of demand will incur penalties proportional to the magnitude of the shortfall.

In one of our previous diaries, we alluded to a number of interactions that could be performed on supply nodes - one of these was a train priority setting. It transpired that this did not fit well with the underlying simulation, and we’ve removed this setting from nodes.

Logistics Strike

Of course, a freight-train loaded with supply makes a juicy target for the enemy. In NSB, CAS and bombers are able to perform the new logistics strike mission, which can put a severe strain on an enemy’s ability to supply their network - actively destroying trains and trucks, as well as damaging railways in the target area.

The strategic bombing air mission will also target rail and supply infrastructure, however the logistics strike mission is a much more effective way of neutralizing an enemy’s fighting capabilities while retaining important industrial infrastructure if you intend to occupy an area for any period of time.


View attachment 752461

Train Variants

As mentioned above, trains will be a researchable technology with several variants. Trains, unlike regular units, are not controllable - their movement and behaviour is entirely simulated based on the needs of your logistics flow. This said, there are several important statistical aspects to them.

View attachment 752462

To begin with, most of your network is likely to be populated by civilian trains. You can construct more of these by co-opting military factories. Further on in your campaign, you can unlock a variant of the civilian train with a significantly reduced construction cost.

To combat the strategic mission mentioned above, there is one (or..is it more?) further item in your toolbox for owners of the NSB expansion. Armored trains, while coming with a higher price tag, are much more resistant to destruction from air missions, and can act as an effective deterrent against logistics disruption.

Train enthusiasts (we have none of those here, right?) will note that the trains displayed above belong to the soviet union - there is indeed unique art as well as 3d models for several other major nations.

View attachment 752463

View attachment 752464

View attachment 752465

View attachment 752466
A highly camouflaged train in action.

View attachment 752467
Displayed trains are based on your stockpiled train equipment. This is the german armoured locomotive!

That’s all from me for today - I’ll hand over here to @YaBoy_Bobby to go over some of the details on supply distribution at a hub level:

Hub to Province Supply Distribution

We have talked about how trains and rails feed the supply hubs, but not so much about how hubs feed divisions in the field. As hubs are fed from the capital province by a rail network, divisions are fed by hubs over land.

Every Hub has an overland range that gives it a collection of provinces that it touches. This range is constant, but the cost of moving over each province is impacted by things like weather, terrain, rivers, and infrastructure. Motorization decreases the penalty for crossing each province, thus increasing the number of provinces a hub will touch and potentially creating greater hub density and thus greater overall supply in an area.

View attachment 752468

As has been alluded to with the phrase “hub density,” a province may be touched by multiple hubs. When multiple hubs touch a province, a ratio is created to determine what percentage of the supply requested each hub is responsible for. Every hub that touches a province lessens the supply burden of other hubs also touching the province.

In the final step, Divisions draw supply from hubs, depending upon the relationship between their current province and the hubs that touch that province. When a hub does not have enough supply to meet demands, the lack of supply is distributed evenly across all divisions currently drawing from the hub.

In older DDs we talked about a penalty to the amount of supply delivered to a province based upon weather, terrain, and distance. Over the summer we decided to remove this penalty as we found it compounded in a hard to predict way that created bad supply and sometimes penalized having more hubs touching a province in a way that we did not like.
Will you also feature in the differences between countries? For example in Russia they use a different railway gauge to the rest of Europe so as Germany would you have to make different trains to counter this
 
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Convoys transport supplies across the sea. They land at a port and then your trains takes them by rail

So the train getting in a ship and then landing somewhere else is an abstraction, isn't it? There's no possibility to sink them as you would troops, equipment sent via lend-lease or resources, right?

Thanks for the reply!
 
Cheers for the DD Arheo and YaBoy Bobby, and the extra info Cranium Muppet and C0RAX (and very impressed by rolling stock rolling onto the LST pic :cool: ) - a great update, and it sounds like a big step forward for HoI4's supply 'game', and that it will have a much more intuitive and meaningful impact on land warfare - sensational stuff :)

As indicated in a previous diary, the logistics network that supplies your troops relies on the large-scale relocation of supply using trucks and trains.

Pffffft, the backbone of the logistics network is the ships that take the supplies and equipment to the ports for the trains to pick them up, but I guess the trains deserve at least a little time in the limelight :p.

One question though - what happens at a recently captured port - does that supply hub use trains, or is that solely truck and ship-based, with inland supply hubs (or coastal supply hubs drawing supply from the interior - there's no accounting for taste) requiring trains to function?

Every Hub has an overland range that gives it a collection of provinces that it touches. This range is constant, but the cost of moving over each province is impacted by things like weather, terrain, rivers, and infrastructure. Motorization decreases the penalty for crossing each province, thus increasing the number of provinces a hub will touch and potentially creating greater hub density and thus greater overall supply in an area.

In older DDs we talked about a penalty to the amount of supply delivered to a province based upon weather, terrain, and distance. Over the summer we decided to remove this penalty as we found it compounded in a hard to predict way that created bad supply and sometimes penalized having more hubs touching a province in a way that we did not like.

This is a bit tricky to get my head around - it sounds (and looks, from the maps C0RAX very kindly shared - cheers :) ) - but I could easily have misinterpreted - that instead of supply being reduced in the distance from the hub, that instead it's a very binary "in supply/out of supply" situation, but with the boundary of that set by conditions - so if it rained and got muddy, my division that was in range of the supply hub could be forced out of supply as the range of the hub decreased? But someone just in supply, but at the extreme distance from the hub, would be in just as much supply as a division sitting on top of it?

You'll have far more data to go on (and I could well have misunderstood), but it is hard to see how this is better than a more graduated approach where rain might reduce but not completely eliminate supply (and do it in a far less black and white way) - it sounds (but hopefully I've got it wrong) that it's going to reproduce the hard binary in/out of supply issues of the current system, but in a different (and, to be fair, less unintuitive) way. I actually think it could lead to greater difficulties in supply prediction, with divisions falling entirely out of supply. But hopefully I'm wrong, and you'll come along and clue me up :)

Not yet ;D

Very nice :)

and the USSR in 36 for comparison (note the use of the river in the north)

Rivers FTW :) I'll do my usual repping of coastlines, as they could be (and were very much during the period) used for this as well.

She remains in working order to this day, often pulling excursion trains and even appearing in movies, including my favorite of all: Tough Guys, starring Burt Lancaster and Kirk Douglas. I recommend it to anyone looking for a good laugh with some of the best actors we've had.

Wonderful - sensational post Idle America :) Evidence of idleness is lacking!

@CraniumMuppet This may be a stupid question, but how are you supposed to transport your trains from Australia to, say, South America? Was transporting trains via sea a thing? Is it possible to sink trains being transported in a convoy? I mean you are not flying the things to the frontline are you?
As C0RAX showed, there were lots of trains shipped all over the place - the USSR got great benefit from lend-lease trains, is probably the single biggest example. In the first supply DD my 'naval pic' was of a Liberty Ship with a bunch of trains on deck :) For an example from WW2, see https://en.wikipedia.org/wiki/SS_Train_Ferry_No._1

And, for a WW2 train-shipping related pic, here's a US locomotive being unloaded from a Liberty Ship in the UK :)



1630581721265.png
 
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I for one am glad to see trains finally make their way into HOI. I may have to break my longstanding rule against pre-ordering content for this.

One question though - any chance of seeing a #TraindesignerDLC down the line?
 
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This is kinda in other posts but I'll try and explain...

The supply system will be abstracted with trains not controllable and 'appearing where needed'. This is the case from all corners of your territory. Fine.

Armoured trains act exactly like conventional trains + inherent resistance to attack. So how do you get armoured trains to areas of higher threat (Eastern front or partisan areas)? If it's a percentage increase to CAS resistance then it's across ALL your territory and not nessessarily in the right place? Should armoured trains be localised or attached to partucular hubs?
 
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Damn, I couldn't be here for the relrease of the dev diary. But you already know what a real train enthusiast would notice in the context of a USSR centered DLC. WHERE IS TROTSKY'S ARMORED TRAIN ? :mad:

Here, I'm done ranting for something that has no real value in the game and would just waste dev time.
 
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What about the country-specific differences?

When Germany invaded the USSR, the railway system provided several problems.

- Different gauges (which means that the Germans had to spend time and resources before they could use the Soviet tracks)
- Different ranges (Soviet steam locomotives had a longer range)
- Different weather (German locomotives were not constructed for extremely cold conditions).

So, will there be some malus for Germany using Soviet tracks?
The different gauges could mean that newly captured Soviet track can't be used immediately.
And maybe a specialization for long-range/all-weather locomotives?
With shorter-ranged ones suffering a malus in the USSR and "summer locomotives" being less efficient in Soviet winters?

Furthermore, I hope that trains can be lend leased.

In real life, the US lend-leased a lot of rolling stock to the USSR.

I am really looking forward to NSB....rail usage could be as important as the introduction of fuel in MTG!
Well, the differences in railroad width were only very particular in Spain and Soviet territories had that particular, since the rest of the European countries had more or less standard width in all of them,
And these specific places would put a small recess or delay than usual to convert those roads as yours to adapt it to the standard width
 
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Why is the mission to attack the lines not available, supplies for long-range fighters, even though it was a mission for fighters of this type such as the P47 thunderbolt

In a future air designer, the fighters should have this type of mission available since allies mainly used fighter-bombers or multipurpose fighters such as variants of the P 51 Munstang or the British MK II Hurricane
 
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The devs have already stated that horses are represented by being able to transport supplies from a hub even without trucks
I already know, but horses should be a tanginible resource to be able to import or export according to needs, like fuel, not something so abstract
 
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Hey! I hope I'm not too late, but I've got a map from the interwar period that displays (amongst other things) the principal railroads of europe. I noticed that some railways on the map are not present in-game, like the one beween Vologda and Archangel. If it's not too late into development, maybe you could take this resource into account. <3
 
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This looks really cool. I like the idea of using military factories to make trains. The only problem I have the with Logistical Strike is that the AI churns planes out en masse, so on a SP campagin this might not be as effective or meaningful if I cannot out produce the Axis or Allies in planes and compete with their 5K fighters. As for the supply, I'm sure you guys have been testing it.

How is the AI (notably the Allies) handling and copping with the new supply. The largeset reason, in game, the Allies don't do as well is that they cram pack into a single state after D-day, which murders the supply. Also, and I'm sure this is being tested. How is this affecting the Eastern Front? Most of the time, the Soviets either fail terribly, the war stalemates, or the Axis get obliterated on Day 1.
The AI can possibly use the Feature that denies allies from using their supply e.g. france can deny america to let them use the supply in northern france
 
has there been any ETA date for this 'not one step back' DLC release ?
i got to say i'm really impressed with the way you developper communicate on your project, please don't restrain yourself like with the removal of weather impacting supply. If it doesn't work you will always be able to balance it in further patches, more depth and realism is never bad for hoi.
 
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No actually. The thing about Mussolini "making the trains run on time" is that he didnt. At no point did he really succeed at making them run faster. What he actually did was have the train schedule adjusted so that the schedule arrival time was the time the trains were usually late by. Innother words, he half-assed it and just declared the delays as being "on-time" instead of actually trying to get the trains to meet it.

Um....welcome to being Germany during WW2. That was something Germany had to face constantly during WW2 and they were never able to stop them even 50%. I see no reason for why the devs should make the AI not make you have to defend German Airspace. If you are having issues and cant spare more fighters, build more static AA and never used concentrated industry, and defeat Russia, so you can actually focus your aircraft on the west.
I was just making a joke. I know he never made them run on time.
 
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Cheers for the DD Arheo and YaBoy Bobby, and the extra info Cranium Muppet and C0RAX (and very impressed by rolling stock rolling onto the LST pic :cool: ) - a great update, and it sounds like a big step forward for HoI4's supply 'game', and that it will have a much more intuitive and meaningful impact on land warfare - sensational stuff :)



Pffffft, the backbone of the logistics network is the ships that take the supplies and equipment to the ports for the trains to pick them up, but I guess the trains deserve at least a little time in the limelight :p.

One question though - what happens at a recently captured port - does that supply hub use trains, or is that solely truck and ship-based, with inland supply hubs (or coastal supply hubs drawing supply from the interior - there's no accounting for taste) requiring trains to function?





This is a bit tricky to get my head around - it sounds (and looks, from the maps C0RAX very kindly shared - cheers :) ) - but I could easily have misinterpreted - that instead of supply being reduced in the distance from the hub, that instead it's a very binary "in supply/out of supply" situation, but with the boundary of that set by conditions - so if it rained and got muddy, my division that was in range of the supply hub could be forced out of supply as the range of the hub decreased? But someone just in supply, but at the extreme distance from the hub, would be in just as much supply as a division sitting on top of it?

You'll have far more data to go on (and I could well have misunderstood), but it is hard to see how this is better than a more graduated approach where rain might reduce but not completely eliminate supply (and do it in a far less black and white way) - it sounds (but hopefully I've got it wrong) that it's going to reproduce the hard binary in/out of supply issues of the current system, but in a different (and, to be fair, less unintuitive) way. I actually think it could lead to greater difficulties in supply prediction, with divisions falling entirely out of supply. But hopefully I'm wrong, and you'll come along and clue me up :)



Very nice :)



Rivers FTW :) I'll do my usual repping of coastlines, as they could be (and were very much during the period) used for this as well.



Wonderful - sensational post Idle America :) Evidence of idleness is lacking!


As C0RAX showed, there were lots of trains shipped all over the place - the USSR got great benefit from lend-lease trains, is probably the single biggest example. In the first supply DD my 'naval pic' was of a Liberty Ship with a bunch of trains on deck :) For an example from WW2, see https://en.wikipedia.org/wiki/SS_Train_Ferry_No._1

And, for a WW2 train-shipping related pic, here's a US locomotive being unloaded from a Liberty Ship in the UK :)



View attachment 752750
Shouldn't "train-shipping" involve a new"special-friend" for Thomas?
 
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Railroads can be build and they can be destroyed, too.

I suggest some nations especially germany (if exist) could use so called "Schienenwolf" railroad plough https://en.wikipedia.org/wiki/Railroad_plough

Bundesarchiv_Bild_101I-279-0901-31,_Russland,_Einsatz_des_'Schienenwolf'.jpg


German railroad plough in action, Belarus (1944)

Maybe that would lower the railroad to 0.0 or something like that. Maybe it need to be activated for every region the player want to use this it need to be activated (also need to be researched but its not difficult kind of technique)

Does other player want this oportunity,too???
 
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