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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In which research section are trains located? Is it in the armored section? And what does the complete technology tree for trains look like, if not a secret? Great diary, by the way!
 
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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.
I've got a question: which parts of the new supply system will come with the free update and which with the paid DLC?
 
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ThePHD

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Would you say we are getting close to release? What else is there to show? It seems like all of the major features have been covered.
 
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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.
 
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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.
Hmm, so SB target options would strictly locked into static structures such as roads, rails, and factories, whilst LS options would strictly locked into dynamic structures such as trains and trucks. Makes sense, to be honest, i rarely put infras as main target for SB anyway. Also, more options for CAS, yay!

Train enthusiasts (we have none of those here, right?)
Sorry, i played Railroad Tycoon II for the Regional Development aspect, not much a railfan myself, lol

Well, this is an engaging feature and surely a welcomed one for me. Thanks, Pete!

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.
Ayy lmao

Also, the diary looks unfinished. I'll post this then refresh.
 
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Aside: it never fails to put a smile on my face that this train DLC has the same abbreviation as the (old) Norwegian train company.

NSB.jpg


Carry on.

Edit to add: if they find some way to make the abbreviation of the air rework "SAS", I'll know it's deliberate.
 
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