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Factories/Attractions send 3 times as much mail as they are sent.

Started by DrSuperGood, June 18, 2015, 05:27:22 PM

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DrSuperGood

I found myself wondering why my industries were sending more mail than they received. Today I ran the maths and they were sending 3 times as much as their "departed" amount showed. Thinking this was a bug I dived into the source code to try and find out why and discovered this...

@line 1916 SimCity.cc (revision at time of writing)

if(  will_return!=city_return  &&  wtyp==warenbauer_t::post  ) {
// attractions/factory generate more mail than they receive
return_pax.menge = pax_left_to_do*3;
}
else {
// use normal amount for return pas/mail
return_pax.menge = pax_left_to_do;
}

So it appears this is intentional. All this time I have been wondering why industries were sending more mail than they received and it turns out this is the reason.

Irritating as the mechanic is (causes asymmetric flow of mail in your network, no wonder I keep having mail build-up at transfers) I understand that it might be intended for difficulty purposes. However some way of communicating that this is happening with the player would be nice so that people are aware it is happening.

Currently the "Departed" Mail amount on the industry itself as well as the city link mail amount (which matches generated) does not match the actual amount of mail generated and departing from an industry or attraction. This is very confusing to players since the actual amount of mail an attraction or industry generates is 4 times the city link amount shows (1 times to, 3 times from). Although one can "write off" 1 times to the industry as part of traffic symmetry (you just need the quoted amount of capacity), it does mean that in reality you need to deal with 2 times as asymmetric mail load which has a huge impact on network design (33% load).

How many people were even aware of this mechanic?

It might be a good idea to re-define the way some of the metrics are shown to make it more clear that this will occur. For example giving attractions a separate departure "mail level" and industry city links displaying both the mail traffic to the industry (currently shown) and the return from it (3 times that). Maybe removing the mechanic for simplicity sake would be a good idea even.

Ters

I did not remember the exact numbers, but that industries are asymmetric has at least been mentioned on this forum. But I have also forgotten why industries send more than they receive. I agree that graphs and amount counters should show the actual number. Anything else makes no sense. The mail levels are however so abstract that I don't think there is any point in showing one for input and one for output. One might wonder why attractions are receiving mail at all. The outgoing is supposed to be post cards I believe.

Isaac Eiland-Hall

It might be fun if industries could define their own mail levels. After all, some companies do market by mail - so a clothes shop might well send out a lot of catalogs. Although in modern times especially, that mail probably comes from a marketing firm or printer rather than the company itself. heh.

And maybe Simuthaners are so crazy that they send postcards :to: attractions as well? :)

prissi

That was there for ages, I think it was already in the code I got from Hajo; or it came very shortly afterwards. The idea was "realism" i.e. people sending postcards from attractions and factopries using mail for advertising.

DrSuperGood

For pakset authors this means that mail needs a lot higher value or cheaper shipping costs. Since you lose efficiency due to the lack of symmetry (and people are even less likely to want to ship it) you need to make it a lot more profitable.

So far for industry I suggest that the "generated" becomes the total of both to and from mail (4 times what it is currently). The departed then shows the mail leaving the factory (makes sense as it has "departed" the factory) and the arrived stays what it currently is (mail the industry receives). The City list in factories should either show the generated amount (both two and from, applies to passengers for consistency as well) or it should break them into separate amounts (passengers/mail to, passengers/mail from). Programmatically I suggest either breaking out the constant (simuconfig) or building it into the factory and attraction pak data (would allow what Isaac.Eiland-Hall suggested) with a default value if data is missing.

Ters

Quote from: DrSuperGood on June 18, 2015, 10:32:27 PM
For pakset authors this means that mail needs a lot higher value or cheaper shipping costs. Since you lose efficiency due to the lack of symmetry (and people are even less likely to want to ship it) you need to make it a lot more profitable.

This would only affect local mail vehicles, typically trucks for me. On the large scale, multiple factories should balance each other out.

DrSuperGood

QuoteThis would only affect local mail vehicles, typically trucks for me. On the large scale, multiple factories should balance each other out.
The factories are only local so they are the worst kind of asymmetry possible (cannot be balanced out). Your convoys literally need to leave towns with 33% mail and return with 100% mail.

Attractions are a different story since they source from housing globally. Hence to a large degree they form some kind of symmetry since usually you get more attractions as you get more people. However the symmetry is still not perfect.

In the Winter pak64 game I was constantly getting a build up of 1k to 2k mail per month at the central exchange. This was because the cities I serviced were some of the most well built on the map (high populations) and had few attractions in the area (as well as pak64 making few attractions). The problem did not stop there as I was regularly having to send extra reverse mail engines to cities to prevent backlogging of 10k or more of mail at my local hub.

Pak128 seems to have more attraction power in each city so the mail back-flow is more symmetrical. However I doubt in the long run the symmetry will hold. I guess the turning point is some amount of city population relative to all other cities since then the "tourist mail" it generates from distant attractions (3 times the amount it sends to them) becomes larger than the tourist mail it generates from local attractions.

Ters

Compared to passengers, I don't remember having any problems with mail in pak64. (Except when it becomes natural to switch from TPOs/RPOs to mail containers, which are much slower than the now pure passenger trains serving the same route.)

DrSuperGood

QuoteCompared to passengers, I don't remember having any problems with mail in pak64. (Except when it becomes natural to switch from TPOs/RPOs to mail containers, which are much slower than the now pure passenger trains serving the same route.)
The problem with asymmetry of mail only starts when you have "wait for 100% load" on some of the stops which demand more mail than they consume. Generally point-to-point lines such as to a hub suffer from this. You almost always want the waiting on the spokes and not the hub as otherwise you end up with massive hubs (all the waiting platforms).

Ters

Quote from: DrSuperGood on June 19, 2015, 05:33:30 PM
The problem with asymmetry of mail only starts when you have "wait for 100% load" on some of the stops which demand more mail than they consume. Generally point-to-point lines such as to a hub suffer from this. You almost always want the waiting on the spokes and not the hub as otherwise you end up with massive hubs (all the waiting platforms).

For passenger and mail, I only ever use wait for 100% load on vehicles serving small villages, plus factories and attractions. Usually with a time-out. I don't usually start doing mail until villages become big villages or towns. That leaves factories and attractions, which then have asymmetry from the waiting side, so there isn't any problems with overflow. These vehicles, whether passenger or mail, usually run at a loss since the time-out doesn't let them fill up. I don't like having them wait too long, as I feel that provides "bad service", even though the game doesn't care. I see these lines as feeders to the main intercity links which is more than making up for it, although that's not really true for factories. (Factories might get a valuable boost, though.)