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!).

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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.


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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.

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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.

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A highly camouflaged train in action.

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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.

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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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Praetori

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This is what happens on real railways, a problem in one place will cause nock on effects in others often far away and seemingly unconnected places, its a Feature not a Bug!!
The problem is presenting it to the players (and getting the AI to handle it) in an understandable fashion.

HOI3s supply system had quirks like that. An armored corps moving around in Poland could cause cascading supply issues that traveled up to the front to central Russia in seemingly weird ways that manifested days or weeks later. It made everyone but the most seasoned micro-managers bewildered and largely made supply predictions neigh impossible.
I'm pretty sure the Dev-team doesn't want to duplicate that kind of game "design".
 
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Sourlol

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Amateurs study tactics, professionals study logistics.

except it seems on these forums, everyone would prefer the computer just handle both. What part of ww2 actually excites people on these forums? Everyone seems to want the battle planner to fight the land war for them, no one wants to actually manage their logistics and production, people would prefer the naval war is abstracted entirely away from anything resembling what admirals had to consider, and people bemoan having to click on air regions to swat bombers.

I constantly see a criticism of “historical players” being they just want to watch a ww2 documentary, yet from the forums I’d say most people don’t want to play the game just watch an absurdist alt history map painting get made.

Rant over...for now
 
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LordWahu

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Everyone seems to want the battle planner to fight the land war for them
I am curious to see how you developed this opinion, because from what I've seen the majority opinion is that the battle planner is a mess that "professional" players don't ever use, and everyone recommends against using
 

Sourlol

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I am curious to see how you developed this opinion, because from what I've seen the majority opinion is that the battle planner is a mess that "professional" players don't ever use, and everyone recommends against using
I didn’t say everyone uses it. I said they all seem to want it to be

there’s like 4 threads in the last month about how the battle planner needs more functionality, how it still shuffled troops too much, how they essentially don’t want to have to micro at all.

everything wanted in those threads is already possible by—you know—playing the game manually. But they all want it to be done automatically.
 
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I didn’t say everyone uses it. I said they all seem to want it to be

there’s like 4 threads in the last month about how the battle planner needs more functionality, how it still shuffled troops too much, how they essentially don’t want to have to micro at all.

everything wanted in those threads is already possible by—you know—playing the game manually. But they all want it to be done automatically.
This is less wanting the AI to handle things, and more for a feature to be more functional

Basically the dream of the perfectionist to see something that is flawed and make it better
 
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Duke_Dave

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I didn’t say everyone uses it. I said they all seem to want it to be

there’s like 4 threads in the last month about how the battle planner needs more functionality, how it still shuffled troops too much, how they essentially don’t want to have to micro at all.

everything wanted in those threads is already possible by—you know—playing the game manually. But they all want it to be done automatically.
I like to play casual rounds where I play with some friends and watch some documentaries in the mean time, chat, etc. so I want to be able to outsource a few things.
 

Warlock-Engineer

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I didn’t say everyone uses it. I said they all seem to want it to be

there’s like 4 threads in the last month about how the battle planner needs more functionality, how it still shuffled troops too much, how they essentially don’t want to have to micro at all.

everything wanted in those threads is already possible by—you know—playing the game manually. But they all want it to be done automatically.
That's because the battle planner is a broken mess that's worse than worthless. It would honestly be better for it to not exist at all than to be included in it's current state, and the fact that the latter is true is something every developer involved should be ashamed of.
 
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Axe99

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That's because the battle planner is a broken mess that's worse than worthless. It would honestly be better for it to not exist at all than to be included in it's current state, and the fact that the latter is true is something every developer involved should be ashamed of.

It's really not that bad - it's wobblier than I'd like (particularly having to redraw battleplan lines when they 'snap' to coasts or borders when I don't want them to, or shrink and leave gaps when I don't want them to) but I often use it, and enjoy it. With a bit of luck, it may have received a bit more work for NSB/Barbarossa :)
 
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plasticpanzers

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Alot of info. Can anybody answer 3 questions on rail. 1) do you capture trains when a country is conquered. 2) Can you bomb bridges to degrade rail going thru that area. 3) Can you loan out trains like Germany did for Italy late in the war. 4) Do you get a Burt Lancaster figure that keeps blowing up different rail lines in France.
 
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