Discussion in 'Civ4 Strategy Articles' started by KrikkitTwo, Feb 13, 2006.

1. ### Roland JohansenDeity

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The other civ will profit from foreign trade routes if it has astronomy and a path through the ocean to one of your borders. If it has never seen a border of your civilization, then it cannot trade with your cities.

2. ### TatranDeity

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I don't get it. Both cities have a cothon, but Carthage seems to be missing a trade
route. Ainu was a barbarian town, maybe a smuggler's route.

Carthage :

Ainu :

3. ### valeMathematician

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Any chance the original post can be fleshed out to answer the following concerns?

1. The original formula breaks down for small values of T or D, projecting domestic route yields of 0 and foreign route yields of 0 or 1. I don't think its just simply that the game does the calculation as shown and then changes the result to 1 or 2 if necessary, but I suppose its possible.

2. How are harbors and the temple of artemis factored in? As a very simple test I put 2 size 1 capitals 3 tiles away from eachother and then set up open borders between the two countries. The yield was 2 commerce. Adding a harbor to one brought the yield up to 3 commerce from that city. Keep in mind the formula is predicting a base commerce of 0 since T=1 here so something is happening that other posts in this thread say do not happen.

3. What exactly is the mechanic for determining how foreign trade routes are assigned. Is it possible that you have foreign cities from civs with whom you have open borders that would provide lucrative trade routes, but none of your cities form a trade route with them? I'm interested in this post by Snaaty about the food economy and trying to understand better how the mechanics work. He seems convinced that infrastructure like harbors and markets increase the likelihood that a city receives foreign trade routes at all.

I've seen lots of save games by lots of players, but the total beakers Snaaty is generating at the break even point for gold in 1100 AD in that game is obscene so having a better understanding of the math behind what is happening (assuming one can handle the diplomacy aspect) would be very enlightening.

4. ### Guardian_PLEmperor

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Sorry for lack of answers, but just few things I like to add and hopefully, elaborate with help of other civfanatics.

From my experience it seems that Snaaty's "hunch" about infrastructure is not yet confirmed, but still I'm inclined to share his opinion - the bigger the city is, and the more buildings it has, the bigger are chances to receive a lucrative foreign route.
It makes sense. If my merchants from say, Paris want to receive a route from London they have to defeat foreign competition from Cuzco, Berlin and Moscow first, which means that Paris has to be bigger and more rich city than Cuzco, Berlin and Moscow. To decide which city gets a foreign route game has to tell which city is better. So bigger, more developed cities will have better routes.

Number of allowed foreign routes have been explained earlier on here, You start with one route (1), then it's GLH (2), currency(1), Carthage's Cothons(1), Free Market (1) and lastly, Corporation (1) that obsoletes GLH. If the game runs that late, count in an airport (1) and Single Currency UN resolution (1)

And also, trade route economy is not viable if one has a huge empire - not enough foreign cities to create routes with all Your cities forces domestic routes, and those are not so juicy. On the other hand, a map with several landmasses offers nice intercontinental trade bonuses, so it's worth to invest in routes on archipelago or similar maps - even domestic routes can be then somewhat useful.

If anything is wrong here let me know

5. ### VirusMonsterQuechua General

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True, because when the possible traderoutes are assigned to each city, the city with highest modifiers automatically receives the highest possible traderoute.

WRONG because there is no competition to traderoutes between two different empires. Say I have Open Borders with 3 civilizations; all of these 3 civilizations will get a traderoute from my most populated city with highest traderoute base profit. The only competition to traderoutes will happen among the cities of your empire.

In your example, even if Paris is smaller and less rich than Cuzco, Berlin, and Moscow, it can still get a traderoute from London (ie city with highest base traderoute profit), assuming Paris has the largest traderoute modifier among the cities of YOUR empire.

With pleasure

6. ### pigswillfly (one day)

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Silly quesion but I haven't seen it answered elsewhere. Do vassals count as foreign trade routes? Do colonies (in BtS) count as foreign trade routes?

7. ### VirusMonsterQuechua General

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Markets and grocers have nothing to do with higher traderoute profits. Snaaty's post on traderoute component to FE is misleading and wrong. The effect of FE on traderoute profits is minimal compared to other economy types. Check this TRE vs FE analysis for a sample scenario between FE and Cottage Economy.

Snaaty used to play his games in Warlords where AI was designed such it grew its cities as much possible. If the AI city has a size 22, then the base traderoute modifier would become, 22/10=2.2 Now, add the modifiers to it:

(150% for foreing traderoute) + (25% capital connection) + (50% for harbour) + (+100% intercontinental) = 325%

Multiply, 2.2 by (100%+325%) = 9.35 rounded down to 9

In BTS, the AI does not grow their cities as aggressively, thus the traderoute profits seem to have dropped. Say 1.5*4.25= 6.375 traderoute profit, rounded down to 6 (33% reduction compared to Warlords data)

Also, in BTS, foreign traderoutes do not get the 150% modifier instantly. At least 50 turns of peaceul relations must pass between your and the target empire for this modifier to reach 150%.

In conclusion, Vanilla/Warlords traderoute profit system seems more advantageous than that of BTS.

8. ### VirusMonsterQuechua General

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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.

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.

9. ### mikebertChieftain

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I'm exploring trade routes. In standard games I always go for the Great Lighthouse and usually have foreign trade routes in all my cities. This is because I tend to have coastal cities and a small number of cities and have open border with all that will have me.

On RFC it is harder and I don't quite understand it. For example. playing the Inca, I sailed over and contacted the Khmer and Chinese. Once I got navigation I figured I would get overseas trade routes. It was hit and miss. In one game, I contacted the Khmer first and got trade routes with them. Then I contacted the Chinese and got trade routes with them, but lost the Khmer, yet many of my cities were still trading with each other. I thought it might be because I lost contant and so I built embassies. Still did not get links will all the foreign cities I knew I had contact with.

Now I am playing Chinese, trying the do the same. I traveled by sea and overland to Persian and India. No trade routes with either. But neither had a port and I certainly had no overland road to Persia. Then India built a port and bang I was trading wiht Persia and India.

Then I made contact with Greece and Rome. After viewing their cities I had no no trade routes with them. But while doing do I contacted Rome and I had routes with Rome, even though they remained entirely black. This by itself is not surprising as I traded with Amsterdam as Inca with no knowledge of a route to Amsterdam.

My guess is Rome has a route to me, even though I have no route to them and so they are trading with me based on their map (my cities are likely the best for them). Does this make sense? It explains the Amsterdam trade route, my city was big, far way and on another continent and so should be super profitable for the Dutch.

But what route could Rome have? There is no overland "silk road" to me, building such a road is a huge task and this is well before the time of the Russians, Germans etc. So it has to be a sea route. If they sent galleys I haven't seen them.

10. ### ditchhookChieftain

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I'm curious about mikebert's questions, too. I'm surprised to read that one of mikeburt's cities has a trade route with a city that is still 'blacked-out' on his world map. I assumed that for any of my cities to have a trade route with any other city, there had to be an exposed route on MY map to that city.

11. ### PieceOfMindDrill IV DefenderRetired Moderator

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For the trade route to exist, IIRC only one of the two players must know where the other city is. I agree it's a bit odd.

12. ### r_rolo1King of myself

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Not exactly. Part of the awnser is in this post from DanF

13. ### PieceOfMindDrill IV DefenderRetired Moderator

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Hmmm I thought that was to do with resource trades. Aren't trade routes handled a bit differently again?

14. ### ditchhookChieftain

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Thanks r_rolo, that indeed was an informative post.

I enjoy very early attempts at circumnavigation (immediately making three workboats, and sending the second and third out in opposite directions). At first I believed I was getting a possible bonus of some early international trade routes. However-- considering the details of DanF's thoughts you just pointed out to me-- I'm now worried I'm actually facilitating better international trade routes for my AI opponents, by establishing routes through MY territory that they wouldn't otherwise have.

15. ### r_rolo1King of myself

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16. ### DanF5771Emperor

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I also like early coastal exploration in order to make contacts and establish lucrative foreign trade routes (the AI does it too while many human players seem to forget about it / neglect it), although I probably don't pursue it as aggressively as you. It should be synchronized with your research path (Sailing / Writing for open borders) and the onset of barb Galley danger.

To take my explanations and the discussion of the other thread linked by rolo further, I'd like to place an example here in Krikkitone's nice article to help players understand the trade network mechanics and their differences regarding resource trades and city trade routes.

The scenario I set up with WB (debug mode view): I'm Bismarck and have the Great Lighthouse in Berlin. My neighbors are Peter and Zara, we all have knowledge of Sailing.

First a picture showing parts of my home plotgroup after toggling the trade groups display in the world view (probably one of the least often used functions in civ ):

You can see the gray patch consisting of all the tiles within my borders which are linked to my capital via road, river, coast and ocean. Berlin has access to all resources on these tiles. But my home plotgroup which is relevant for establishing trade networks with my neighbors extends further -- right now all revealed land tiles adjacent to the rivers plus all revealed coast tiles outside of my borders are also part of it (enabled by Sailing, ocean tiles outside of a players culture require Astro).

Normal view of my explored tiles:

I have sent my Workboat to Peter's borders. The unowned coast tiles uncovered by the Workboat got added to my home plotgroup. Once I found the first coast tile within his culture, all tiles of Peter's gray patch (excluding his ocean tiles) joined my home plotgroup too.

The rule is that a tile is allowed to join a players home plotgroup if
• the tile is adjacent to the plotgroup
• the tile can be part of a trade network according to the player's tech level (tile has a road/railroad, is adjacent to river, is coast/ocean terrain and player knows Sailing/Astro)
• the tile is either revealed by this player or owned by anyone not hostile
• the tile is not blockaded by an enemy ship.
So now both Berlin's plot and Moscow's plot are part of my home plotgroup -- I have established a trade network connection Berlin --> Moscow traderoute: in the scoreboard). This connection is unidirectional, since Peter hasn't sent a Workboat yet, so his home plotgroup only comprises his gray patch and the adjacent tiles he has revealed, but not Berlin's tile. This means that we can both trade resources, but only I can benefit from a trade route Berlin --> Moscow.

I don't know where Zara's capital is, but I can trade resources with him too traderoute: in the scoreboard). He sent his Workboat around my island and established another unidirectional trade network connection Aksum --> Berlin (Berlin's plot is in his home plotgroup but Aksum's plot isn't part of my home plotgroup).

Zara's view and capital with his trade route to Berlin:

Now the funny and interesting fact -- Aksum pops its borders into the third ring (100) so that Peter's and Zara's gray patches touch. As there are no unowned AND unrevealed tiles left separating my home plotgroup from Zara's patch, all of Zara's patch tiles (\ocean) including Aksum's plot join my home plotgroup during the next recalculation. This turns the unidirectional trade network connection Aksum --> Berlin into the bidirectional connection Berlin <--> Aksum, so that Berlin can have a trade route to Aksum as well, in spite of me still being clueless where on earth this city might be located.
I've marked the tiles of ONE possible path through my home plotgroup from Berlin --> Aksum, going through Russian territory. It doesn't matter whether I have open borders with Peter or not, I just must not be at war with him.

~~~~~~~~~~

Thus aggressive early exploration by the human player does not give any major advantages to the AI as it doesn't enable trade routes for them, but they might show up demanding resources.

17. ### ditchhookChieftain

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Thanks very much, DanF! If I may continue to pick your brain, how do blockading ships interact with plotgroups?

Consider this informative post (http://forums.civfanatics.com/showpost.php?p=7950314&postcount=8). It seems to me that a blockading ship at the right 'choke point' can disrupt a significant amount of trade, even if the blockading area is not close to the affected civ(s). Am I right to assume that a blockading ship creates a 9x9 square temporarily disrupting/amputating all 'enemy' homeplots (or in the case of privateers, all homeplots except the owner's)?

18. ### DanF5771Emperor

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^ Exactly! Well almost -- it's a 7x7 square (SHIP_BLOCKADE_RANGE = 3 in GlobalDefines.xml). Blockaded tiles cannot be part of enemy plotgroups and for Privateers all other players apart from the owner are enemies (I'll add this to my list of prerequisites in my post above - thanks).
If you can get to Privateers early you can seriously mess up AI trade networks. But once the AIs have Astro their impact diminishes + bring them home quickly when the AI gets Chemistry too!

19. ### YuufoChieftain

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Hello,
nice to see an in-depth analysis of this part of the game.

If I may benefit from your experience, I would like to submit the following question :

I own this Chariot, my Turkish civ has trade network up to the Mayas' territory. I see the purple borders across the sea (Babylon) but I don't know him at this time. Neither of us has Astronomy at this point of the game.
Hopefully his borders will expand over the ocean tile and I will gain contact to him. I will thus gain with him.
The question is : if I open the borders, will either of us benefit from trade routes with the other?

Thanks
Yuufo

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20. ### DanF5771Emperor

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As mentioned in the post above it gets a bit tricky when it comes to Ocean tiles and establishing pre-Astro trade network connections.

If you don't build a city at this coastline in order to cross the Ocean with your own culture, you will not be able to establish a link Istanbul --> Babylon until you learn Astro, thus you will not get any trade routes to Hammurabi's cities. Neither will you be able to trade any resources immediately after contact (no !). You will have to wait until Hammurabi sends a boat to explore your continent, so that he will have Istanbul's plot in his growing home plotgroup leading to the unidirectional connection Babylon --> Istanbul. This means that only he will benefit from the lucrative intercontinental trade routes (consider keeping your borders closed).

Imagine Galleys travelling on the trade routes between the continents -- the player who can send his Galleys across the Ocean receives the trade routes. For resource trades the ownership of the Galleys doesn't matter.

I've changed Zara's island in the example above so that it is separated by a narrow stripe of Ocean tiles from Peter's and my continent. The pictures display my home plotgroup (black area) before and after the terraforming. My home plotgroup cannot contain Ocean tiles outside of my own culture, so that I lose Aksum's plot and the juicy trade route to it. I can still trade resources with Zara traderoute as Berlin's plot is still in his home plotgroup (Aksum --> Berlin).

btw, Hammi seems to need a border pop into the third or even 4th ring of this city in order to cross the ocean and make contact. I'd try to get the Chariot to 5 xp via barbs (or build a new one with Barracks + Stables) and promote him to Sentry, then move him to the hill 1N of where he is now so that you can make contact earlier.

Edit:
It just occurred to me that cultural borders cannot extend further than 2 tiles away from the home continent into the Ocean, so a border pop of Hammi's city into the third or 4th ring won't do the slightest thing ...

Last edited: Apr 20, 2009