MANY Trade Route Questions

[InovA]

I've been reading up on Trade Routes and the commerce generated from it, along with how they come to be. My questions (in bold) are about some of the specifics, players opinions on how best to take advantage of trade economy, and to make sure I understand these mechanics correctly!

Spoiler First, the formula for commerce generated from a single trade route: :

[(1+F)*(5*(Pop-10))+100+Cap)* (Minimum ([T*50%], [D*70%]))*20%/100]

F is 150% (1.5) if it is a Foreign Trade Route, 0 if domestic
Pop is the Pop of the city Getting the trade route
T is the Pop of the City the Trade Route is With
D is the Distance to the City
Cap is 25 if one of the cities is conected to the Capital, 0 if not
[] indicates rounding down

I hate the way this was set up, there's a missing opening parenthesis (or an extra closing) in the first half and percentages are used instead of their decimal versions, but I'm assuming the formula is:
Commerce Generated = [((1 + F)(5(Pop - 10)) + 100 + CAP) * (MIN([0.5*T],[xD]) / 500]
where 'x' is the map size modifier:

Spoiler Vanilla map modifier values :

Duel is 80%
Tiny 70%
Small 60%
Standard 50%
Large 40%
Huge 30%

However this is all for VANILLA Civ 4
Many in this thread (https://forums.civfanatics.com/threads/trade-routes.159047/), while talking about vanilla Civ 4, mentioned that the harbor's +50% bonus applies before the (MIN([0.5*T],[xD]) step rounds, so its bonus doesn't stack with the foreign trade bonus (or other bonuses), making early harbors worse than anticipated.

Does the harbor's +50% bonus work such that it stacks after the base value has been calculated, or does this problem still exist? (I'm guessing the portion below is the answer, but just want to be sure)

Spoiler KrikkitTwo's explanation given for BTS :

Editing for BTS:
BTS explains it a lot better in that there are 2 components to trade
1.= Base value
Base Vaue is the SMALLER of
Population of Other city/10
AND
Distance to the other City * 15%->40% (Huge->Duel)
but Base Value has a Minimum possible value of 1

2. Modifiers, these are all +% and are added together and then the total is used to modify the base value.
Then the Base Values have % modifiers added, the % modifiers are
+5% for population of the Receiving city over 10
+25% if the receiving city has a connection to the Capital
+3% per turn since your last war with the civ (if it is another civ) [max 150%]
+50% if you have a Harbor
+100% for the Temple of Artemis
+100% if the other city is on another continent
+100% if it is another civ on another continent AND you have a Customs House

So I take this as a new formula being used: (Basically the same as above, but with tweaks)
Commerce Generated = [Base * Modifiers]
Base = MIN([0.1*Popother],[xD]) : with a minimum of Base = 1
Modifiers = SUM of bonuses

I included the brackets in MIN([0.1*Popother],[xD]) as an assumption, is the base value still treated as an integer or does its decimal stick until after modifiers are applied?

Also the BTS explanation states "15%->40% (Huge->Duel)" so I assume it's just:

Spoiler BTS map modifier values :

Duel = 0.4
Tiny = 0.35
Small = 0.3
Standard = 0.25
Large = 0.2
Huge = 0.15

How is the sustained peace modifier (+3% per turn since last war with this foreign civ) initiated? (i.e. Does it start on turn 1, does it start the first turn you meet them, does it start the first turn a trade route is possible?)

Is the sustained peace modifier of +3% per turn the same across all game speeds, or is this the standard speed's variable?

Is the +25% connection to Capital as simple as it sounds? As long as the city has at least one road, river connection, coastal (with Sailing), or oceanic (with Astronomy) connection, it gains the +25% bonus?

Side question: If a city without a connection to the Capital has a connection to a strategic resource, can you trade that resource to a foreign civ?

DanF5771's post in the thread (https://forums.civfanatics.com/threads/trade-routes.159047/page-6#post-8318782) states that the distance to the other civ is measured as plot distance. Think he explained it well, but to be sure...

Is this how the distance is calculated?:

Spoiler :

Distance = MAX([X + (Y / 2)],[(X / 2) + Y])

He gives an example so I'll try my own to be sure:
If a city was 11S and 24E then
Distance = MAX([24 + (11 / 2)],[(24 / 2) + 11])
Distance = MAX([24 + 5.5],[12 + 11])
Distance = MAX([29.5],[23])
Distance = 29

Another post by DanF5771 (http://forums.civfanatics.com/showpost.php?p=7698429&postcount=7) teaches me how cities discover and add each other to their possible list of trade partners, but part of it I'm uncertain over.

I understand the nodes designated as "home plotgroups" and that if I'm on the southern end of a skinny continent with De Gaulle in the middle of the continent (owning both coasts) and Churchill on the northern end of the continent, I can trade with any city of both civs (if I have Sailing and we all have open borders and at least 1 coastal city connected - not blocked by ice, etc.). Regarding tiles trade networks can be established through, DanF5771 states "the tile must either be revealed OR owned by a non-hostile player" so if I only have open borders with Churchill but not De Gaulle, then I can still establish trade routes with Churchill. But if I'm at war with De Gaulle, I cannot trade with either civ until I've eliminated the French culture control from the proper coast.

That part I could follow, but the bidirectional and unidirectional portion tripped me up a bit, after thinking it over I think I got it:

That above quote is important and can be taken the wrong way. Should it be rewritten as "the tile must either be revealed by you OR the tile must be owned by a non-hostile player"? This would remove confusion of thinking if you stay at home forever and the non-hostile player reveals everything for you, the trade routes can be established. OR Should it be rewritten as "any non-hostile player must have revealed the tile" which would include whether or not they owned the tile and suggest that a player's scouting isn't as necessary for trade networks. I believe the correct way is the former.

Would this be true?:

Spoiler :

If I restate this scenario, this time let's pretend there is a strip of a few tiles between all 3 of our civs. So from north to south: Churchill - a few unowned tiles - De Gaulle - a few unowned tiles - Me. We've all met, all have a city on each coast, have NO roads/rivers to each other, and all have Sailing. If I have revealed land tiles all the way up to De Gaulle and Churchill, but no coastal tiles. This means I can not establish a trade network, will receive no trade route bonuses, and cannot trade strategic resources. Now if they have both revealed coastal tiles all the way to me, they may both receive trade route bonuses but I cannot, BUT now we can trade strategic resources.

This means there are unidirectional trade routes (to them, not me) and bidirectional trade routes (only among the two of them).

Do you think building a castle for +1 trade route is ever worth it? 150 for wall + castle doesn't sound great, but 75, if you have the Protective trait, for just your largest cities that can access foreign cities, it could be good. With Temple of Artemis and a harbor, this could pay for itself in under 10 turns for those with Protective trait. Too bad it only lasts until Economics.

VirusMonster's post states that vassals count do not count as foreign:

Spoiler :

Vassals are a BTS concept. BTS does not use the foreign trade route modifier anymore, instead it uses a sustained peace modifier that increases +3% every turn to a maximum of 150%.

The following picture is taken while running Mercantilism, and the French being a vassal of Roman empire.


View attachment 170759

As you can see, the sustained peace modifier is in effect, and traderoutes from the vassal do not count as foreign; otherwise, Mercantilism would not have allowed such traderoute to exist.

Colonies follow the same mathematics.

But http://civilization.wikia.com/wiki/Trade_route_(Civ4) states that vassal cities count as foreign for Customs House and Sustained Peace benefits. So...

Do vassal cities count as foreign, but are not prohibited by Mercantilism? So you'd still only have 1 possible trade route to each of the vassal cities.

Also, while looking at that wikia page I see trade route yields are defined by:
base_value = max(1.0, min(pop(To)/10, dist_factor(mapsize)*plotDistance(From, To))
and map size modifier is defined as 16%/14%/12%/10%/8%/6% for duel/tiny/small/normal/large/huge.
I'll assume this should be trusted over KrikkitTwo's 11-year old thread that gave much higher modifiers, but my question about whether or not it's treated as an integer or double/decimal before modifiers still stands.

Can you manipulate, mid-round, what city can have the foreign trade routes? I know only 1 foreign city can trade with 1 of your cities, while domestic cities can trade with an infinite amount of other cities, but since your biggest cities are selected first for foreign trade, if your main cash/science city (Wall Street + Holy Temple + towns, etc.) didn't have foreign trade to amplify more greatly than another city which has the larger population, if you whipped the larger city, would its trade routes be available for the cash/science city to take immediately, or would it have to wait for the next turn?

In recent thread (https://forums.civfanatics.com/threads/quick-economy-question.620374/) PsychopathicWarmonger is having troubles with his economy after REXing and overtaking an opponent too quickly without sufficient commerce tiles to work. Elitetroops suggests

Settle the one tile island east of the continent asap. It will double your current trade route income.

This advice is because of the "+100% if the other city is on another continent" bonus to trade routes and because domestic cities can have an infinite number of trade recipients, so every other city of his would begin trading with it immediately, correct?

Sorry for the long post, here is a banana for you!

 

[elitetroops]

Can you manipulate, mid-round, what city can have the foreign trade routes? I know only 1 foreign city can trade with 1 of your cities, while domestic cities can trade with an infinite amount of other cities, but since your biggest cities are selected first for foreign trade, if your main cash/science city (Wall Street + Holy Temple + towns, etc.) didn't have foreign trade to amplify more greatly than another city which has the larger population, if you whipped the larger city, would its trade routes be available for the cash/science city to take immediately, or would it have to wait for the next turn?

At least trade routes are recalculated when you settle a new city. Typical situation where this comes into play: if you settle a city, then complete a road to it the same turn, it does not generate trade route income the first turn. If you do it the other way, first complete road, then settle city, it will generate TR income the first turn. Maybe in some case it could make sense to settle your new city last, if whips or other things can influence your trade route income. I'm not sure if conquering a new city also causes trade routes to be recalculated.

This advice is because of the "+100% if the other city is on another continent" bonus to trade routes and because domestic cities can have an infinite number of trade recipients, so every other city of his would begin trading with it immediately, correct?

Yes. Since the player in that case had no foreign trade routes and one trade route/city, all worth 1 commerce, settling an island would have doubled all existing trade routes (and of course also generated a new 2c trade route from the new city).

 

[Fine_Distinction]

Great questions. Necromancing this thread.

I also wonder about “sustained peace bonus”. And whether vassals are foreign.