How To Maximize Trade Between Two Cities?

[Zenon]

Sirsnuggles, that is also my experience. Continents affect the delivery payement, not the trade route. What I am missing in this thread is the mention of the road and railroad bonus, the earliest way to improve trade routes.

Zenon

[rah]

Yes, continents may not affect the trade route but it's really boosts the delivery bonus.

[Thoddy]

Originally posted by sirsnuggles
The only trade-route penalty pertains to trade routes between cities of the same civ.

Airports add 50% (to the base) if they are present in both cities.

Superhighways are like the way Samson described them in his bonus post (they can effectively double the trade route). They increase base trade, and then increase trade route by another 50%.

It does not matter whether a caravan or freight initiates the route.

There is one odd anomaly that I've noticed, but you'll have to wait for that.

dont forget additional effects of road/railroad on the optimal path between cities if distance is less than 22 tiles. use partisans to check the optimal path.

If the optimal path is blocked somewhere by an opposing unit this additional effect will vanish.

And what about the effects of corruption: Gouvernments, Courthouse and road/railroad on optimalpath to capital if distance city-capital is less than 22 tiles.

Keeping this in mind gives you some additional trade-arrows in the earlier game.

[duke o' york]

Originally posted by Zenon
Sirsnuggles, that is also my experience. Continents affect the delivery payement, not the trade route. What I am missing in this thread is the mention of the road and railroad bonus, the earliest way to improve trade routes.

As far as I can remember, two land masses linked only by one of the poles are treated as different continents for the purposes of calculating trade route delivery bonuses.

[Elephant]

Originally posted by Thoddy

dont forget additional effects of road/railroad on the optimal path between cities if distance is less than 22 tiles. use partisans to check the optimal path.

If the optimal path is blocked somewhere by an opposing unit this additional effect will vanish.

And what about the effects of corruption: Gouvernments, Courthouse and road/railroad on optimalpath to capital if distance city-capital is less than 22 tiles.

Keeping this in mind gives you some additional trade-arrows in the earlier game.

Partisans dont show up in "the earlier game", but Explorers are a good substitute. It has to be something that gets that special "all terrain treated as roads" status, otherwise it will deviate for nearby river systems.

Best way to prevent path blocking is getting an alliance with the destination civ.

Corruption is difficult to factor in, partly because we often make the SSC the capital or move the Palace there ASAP.

[rah]

Originally posted by duke o' york
As far as I can remember, two land masses linked only by one of the poles are treated as different continents for the purposes of calculating trade route delivery bonuses.

The easiest way to tell is by looking at the continent number of the two city squares. If they're different, they're considered on different continents for trading purposes.

[Elephant]

Some other issues with partial solutions related to Trade Routes:
- What the game uses to decide which route to keep or replace when you already have 3 routes;
- How the game treats TRs on flat maps when "wrapping the date line" is shorter than the other direction.

I have seen anomalies with both issues in recent play.

[Thoddy]

Originally posted by Elephant
Some other issues with partial solutions related to Trade Routes:
- What the game uses to decide which route to keep or replace when you already have 3 routes;
- How the game treats TRs on flat maps when "wrapping the date line" is shorter than the other direction.

I have seen anomalies with both issues in recent play.

The game checks trade routes at the beginning of every turn and also if you open the city window. It checks all routes from this city to other cities and all traderoutes from other cities to this city. So normally more than 3 routes has to be checked.

The 3 best routes will be identified and they replaces less efficient ones displayed in the city window.


Trade routes over the dateline loose their road and railroad bonuses even the distance is less than 22 maybe 24 tiles.
the calculation is buggy.

[Scouse Gits]

The 3 best routes will be identified and they replaces less efficient ones displayed in the city window.

This in my experience is false! Oftimes a local route will displace a more lucrative foreign trade in the middle to late game

Stu

[Thoddy]

I didnt check the bonuses from foreign trade.

the formula detecting the best trade cities maybe buggy.

http://apolyton.net/forums/showthread.php?s=&threadid=52337&perpage=20&pagenumber=2

http://apolyton.net/forums/showthread.php?s=&threadid=64729&perpage=30&pagenumber=2

[Zenon]

When additional trades are made, the existing routes of any city will not be replaced unless the base trade of its newest trading partner is greater than that of the base trade of one or more of the cities used to establish the existing routes.

This statement is from Solo´s EL Guide and consistent with my experience. It is the Base Trade without trade bonus (qualified road, railroad, foreign) that determines which trade route is applied or replaced. That is the reason why it is relatively easy to replace a high valued foreign trade route (+100% bonus) with a lower valued trade route from an own city (no bonus). AI cities usually do not have a good trade base.

Zenon

[Elephant]

That's my thinking as well.

Here are my "working" results on Trade Routes. These borrow heavily from Samson's work on Delivery Bonuses; I am assuming that similar algorithms are applied in the same order. Most of these I have verified in at least three games; I implore others to test these formulas in current games and report anomalies back to this thread.

NOTE: All calculations are Civ2 Integer Math: after multiplying or dividing, drop any remainder; there is no "rounding".

BASE TRADE ROUTE:
TR=(T1+T2+4)/8
T1,T2="Base" Trade of city terrain, subtract TRs (does include Colossus, SH, Rep/Dem or WLTKing/Comrade/HighPriest)

The Base Trade number is used when a city has three existing trade routes and an extra route is completed (either direction). Only the three routes listed are checked; other cities may have routes TO the city without a reciprocal route back. Routes with the three cities with the highest Base Trade are kept. If two are the same, the oldest is kept.

NOTE: If you have lucrative routes to an AI city that depend on using Multipliers, reducing your domestic city's Base Trade under that of the AI city will allow the route to be one-way and not disturb the foreign routes.

MULTIPLIERS:
*(NO MapSize Multiplier)
*(NO Different Continent Multiplier)
* -50% if both cities are Same Civ
*(NO Freight Multiplier)
*(NO Demand Multiplier)
*Transport (add together before multiplying):
...+50% for KeyRoad From SourceCity To DestCity (alternative: StationCity; limit: 22 tiles), or
...+100% for KeyRR From SourceCity To DestCity;
...+50% for SuperHighways in Source city (increases BaseTrade too);
...(NO +100% for SuperHighways in both cities, just BaseTrade increase);
...(No +50% for Airports in both cities, same continent);
...+50% for Airports in both cities, different continent (down from 100%).
*(NO AgeModifier)

[Zenon]

Good work, Elephant! I don´t think the effects of superhighways and airports on trade routes have been described at all before.

Originally posted by Elephant
NOTE: If you have lucrative routes to an AI city that depend on using Multipliers, reducing your domestic city's Base Trade under that of the AI city will allow the route to be one-way and not disturb the foreign routes.

Exactly. I would just add, that this works the other way, too. Replacing an existing trade route may unblock supply commodities. When delivering again to the AI reducing the domestic cities Base Trade allows to reestablish the lucrative trade route (and possibly to unblock the commodity again). And this way the delivery bonus is not reduced.

Zenon

[rjmatsleepers]

Originally posted by Scouse Gits

The 3 best routes will be identified and they replaces less efficient ones displayed in the city window.

This in my experience is false! Oftimes a local route will displace a more lucrative foreign trade in the middle to late game

Stu

This has been my experience as well. In particular, I remember a number of times when a domestic route was not replaced despite converting all the workers in the source city to elvii. (I hope I have correctly understood the way of calculating base trade.) I will try to find some examples to post.

RJM at Sleeper's

[rah]

Originally posted by Scouse Gits
This in my experience is false! Oftimes a local route will displace a more lucrative foreign trade in the middle to late game

Stu

I thought the same but will have to reexamine it based on Zenon's comment about Solo's guide.