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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!).

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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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Hello. One question, have you incluted railroad sabotage into espionage and resistance ? The factories can get sabotaget and railways should be able too. That is what happened in reality during ww2 in occupied Europe.
I really hope so because one of the LaR espionge missions actually references blowing up a train bridge/tunnel.
 
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Looking forward to this! Will we be able to do a 'logistics strike' style mission against supply ships? That kind of thing happened a lot in the Med and Atlantic at a minimum iirc.
I remember reading on these forums that naval bombing emcompassed that, but they removed it on account of the AI being unable to deal with it. Maybe someone can correct me?
 
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WtT had 28 dev diaries, MtG had 30, and LaR had 24 or 25. We're currently on 19 of actual content, so still a couple more weeks I imagine; one or two more bag of tricks, achievements, AI stuff, railway guns, any last minute changes they did to trees, and maybe new modding options would put it to 26, still got a bit to go imo :)

I'm really disappointed by the slow pace of NSB development so far.:(

You guys annouced that update way to early or you progress very slowly.

TfV 1st annoucement untill release >>> 83 days
DoD 1st annoucement untill release >>> 63 days
WtT 1st annoucement untill release >>> 176 days
MtG 1st annoucement untill release >>> 281 days
LaR 1st annoucement untill release >>> 188 days

NSB 1st annoucement untill now >>> 153 days
This time we got no release nor even a world war wednesday in sight and most of the content you showed us are focus trees.
Some of the stuff you showed us prior you even cancelled today.
 
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They are harder to kill. If you can convince the enemy to form a large line on a train track, you may have a good use case for offensive train warfare... but in HoI - nope.
There was a mod for Age of Empires 3 that let any units caught on the tracks when a train passed take trample damage. Could be fun.
 
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Sorry to hear about the weather effects being removed, is there any other penalties to supplies or troops from bad weather.
They moved to weather effects to the overland range from the hubs to the troops. Weather is still relevant, just not where they initially put it.
 
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I've always found it kind of weird how a silent peaceful front would consume the same ammount of supplies of an active front, unlike how it works with the fuel mechanic which is only drained when the unit is moving or fighting. Will this be touched at all in the DLC? I haven't seen all the dev diaries.

Ammunition is represented by attrition of equipment. Supplies only covers food, water, clothing, etc. for your troops. Hence why two fronts with the same forces will use the same supplies but very different equipment attrition depending on levels of combat.
 
what about the horse production? ;);)
Cue funky bass lines. Cue champion stallion prancing arrogantly into the breeding paddock. Cue partisans slipping a few goats and chickens into the paddock [logistics disruption mission] while liberating the nervous-looking filly. Stallion shrugs, smirks [Rocky is a pro after all]... and that goat will never be the same.

boom-chicka-chicka-boom
 
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In the previous developer’s diary, it was mentioned that the supply trucks used by the hubs do not consume fuel. Is there any chance you’ve reconsidered it? Unfortunately, trucks had the disadvantage of fuel consumption, even if they were more efficient.
 
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Ammunition is represented by attrition of equipment. Supplies only covers food, water, clothing, etc. for your troops. Hence why two fronts with the same forces will use the same supplies but very different equipment attrition depending on levels of combat.
So, soldiers spend ammunition (suffer attrition) when going up mountains but not when attacking on plains?

Two fronts, one quiet and the other attacking on plains, will spend the same supply AND suffer the same attrition (none)
 
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Depending on the detail of the new supply system, could we see the weight of a division being used to determine how many trains would be needed to transport it strategically? This would bring meaning to either supply or quicker redistribution of your armies if you had limited rail stock. Make players take hard choices at times. Could be switched off for MP.

Also SOE helped the French resistance (bunch of French teenagers) in June 1944 swap out the train engine oil for abrasive powder which rendered the trains inoperable just when a German armoured division (not mentioning name) needed them to get to Normandy quickly. It had to go by road and suffered much attrition for it. Just thought this mission could be added?
 
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