Caravan Price Spike

My economy is based on caravan production.

I find the highest-paying trade route and push every caravan down that same path. Every caravan no matter where it's produced goes to Sidon to make that its hometown. Then they all go halfway around the world to Babylon for the big payoff (typically $247).

Suddenly without a population increase in either city, the price jumped to $294 . Before I've even finished planning how to spend this windfall, the price is back to $247. The spike only lasted one turn.

Has anyone else seen this? I would love to know what I did right for that one turn. Maybe make it last.

Update on the proce spike:
While I don't know how to make it happen, I've found out at least one thing you can't do.
If you open and close the city display of the city the caravans are coming from, the price bonus ends. I had a bonus price of 359 gold per caravan.
Open the Sidon city display and immediatelt close it again - the price plummets to 261 per caravan: the "normal" going rate.

The bonus price situation appears to be very delicate. Opening the city display isn't the only thing you can do to kill it. I just lost the price without opening the city display, but I haven't figured out what did it this time.

I think I've finally figured out the price spike.
Managing for maximum caravan value is rather involved, but well worth the trouble if you play it right.
Bonn1 shows the city where my caravans originate.
Arrive1 shows a Bonn caravan arriving in London after city check.
Bonn was built to be as far from London as possible while maintaining a high trade value. There are two things about Bonn that bring about the price spike.
1) It already has 3 trade routes.
2) It is completing its barracks on "Auto".
The trade routes are with rivals. I don't know if the trick works with friendly routes.
I have tried it when Bonn had only one trade route. Building an Auto improvement had no effect.
The trick works with any automatically selected improvement.
The trick works with any city, but best where distance and trade already combine for a high payoff.

The bonus price lasts for at most one turn after an auto improvement is completed.
The price is canceled if you do any of the following:
1) Open the Bonn city display (any other city display is safe including sending diplomats to investigate rivals - even London).
2) Check any of these advisors: F1, F4, F5, F8, F9.
3) Check demographics.

Arrive0 shows a caravan arriving in London after canceling the bonus.

These actions do not cancel the bonus price:
1) Send a caravan to Bonn and make its home there (as long as you don't look at the city display)
2) Any of these advisors: F2, F3, F6, F7, F10.
3) Save and load the game.

This sounds like a wonderful trick, but there is a limit.
Bonn2 shows Bonn with the tax man put back to work on the farm.
Arrive2 shows the Bonn caravan arriving in London from this city after city check.
The treasury balance starts out better because of the revenue from working the land, but the caravan price is a disappointment. There is an overflow condition here.

Sounds like a bug, as the additional trade from having the taxman back and earning his keep would not improve the price 50%.

The 'auto' condition causes many bugs. Another one is the way it can make a unit fortified in the city 'disspear' until taken off 'auto' production, which is a real pain if defending during a surprise attack.

That is interesting. I have never seen the disappearing defender problem. Do you mean disappear as is not displayed or disappear as in completely disbanded?


Now let me clarify my earlier post. Putting the taxman to work on the land did not increase the price from 231 to 320. Caravan price crashed from 320 to NEGATIVE 315. Ouch!

Here is what Bonn caravan values look like trying variations in the city check:

No "Auto" bonus, with taxman : 231
No "Auto" bonus, no taxman : 241
With "Auto" bonus, with taxman : 320
With "Auto" bonus, no taxman : -315

Here is how I've tried to piece together what happened.

This is Bonn's trade with the taxman.

60 (12 ocean squares @ 5 arrows each)
20 (5 squares @ 4 arrows each)
3 for the center square (no railroad)
---
83
41 (50% bonus for "Auto") - This is just a guess, but it's probably close.
---
124

And without the taxman...

60 (12 ocean squares @ 5 each)
24 (6 squares @ 4 arrows each)
3 for the center square (no railroad)
---
87
43 50% bonus for "Auto"
---
130 ==> This is -126 in an 8-bit integer and this is what busted the caravan price.

From what I've seen, it appears that each city's trade is tallied in an 8-bit integer before entering into the caravan value calculation which is done in a 16-bit integer.

At this point, of course, this is just speculation.

I've encountered the disappearing unit a few times, never made any connection of events that caused it. I never do auto-build, so that was never the cause in any of the cases I've seen.

In my experiences with this, the fortified unit is shown in the city display, and you can select him, allowing you to move him out, as normal. But, when he is in the city, the city acts as if not defended. You don't see the subtle border around the city square on the main screen, and any enemy unit can move in and capture it, as if it were undefended. In fact, I've moved another of my units in, and I re-captured my own city! That hurts, as it has the same effects of capturing an enemy city (population decrease, loss of some buildings).

Screech said:

... You don't see the subtle border around the city square on the main screen, and any enemy unit can move in and capture it, as if it were undefended. In fact, I've moved another of my units in, and I re-captured my own city! ...

Click to expand...

This is certainly as strange phenomenon. The city is your color but you can’t click on it and get a response. If I remember correctly if you wait until that city build finishes you can get control and un fortify or sentry the unit. But I think you still get the capture city scenario when you enter the city. I have looked at the city table and on the surface all seems normal. The next time I see this I’ll have to do a save and see if I can spot anything unusual.

An easy way to cause this to happen every time is to create a new unit for an enemy civilization right on top of a new city that you give them. As long as the unit stays to defend, the city should appear undefended (until a new unit is built, that is). This can also happen to a human player (and as said you will 'capture' your own city if you move a different unit into the city without removing the 'invisible' unit first).

Dack said:

This is certainly as strange phenomenon. The city is your color but you can’t click on it and get a response. If I remember correctly if you wait until that city build finishes you can get control and un fortify or sentry the unit. But I think you still get the capture city scenario when you enter the city. I have looked at the city table and on the surface all seems normal. The next time I see this I’ll have to do a save and see if I can spot anything unusual.

Click to expand...

Take a look at my save game that I just uploaded in January 2007 GOTM (Great Barrier Reef scenario). The city Delhi is exhibiting this phenomenon. In fact if you look at my replay, you can see that I re-captured it at the very end when it was already mine.

Years ago, I saw this "recapture your own city" glitch and had no idea what was going on. I just assumed that I had been hacked by an enemy diplomat. Thanks for enlightening me.

Lately, I have managed to avoid the unreachable city problem by not fortifying units and by not going "auto" until I buy the desired improvement.

While there is an obvious downside to playing "auto build", there is also an upside. To illustrate this, I submit the city of Tyre. Though it may not look it, this city is in celebration. The 50% bonus for completnig an auto-selectetd improvement applies to all trade across the board. The city is celebrating because luxuries are increased by 50%. Tyre is also generating 50% more research than the light bulb graph indicates.

I've been playing this game 20 years and I haven't seen the auto button in probably about 15 years. I play the game without noticing it. I forgot it even existed. I was completely confused when you guys were talking about auto. I must test out the auto thoery valen posted.

Valen said:

Lately, I have managed to avoid the unreachable city problem by not fortifying units and by not going "auto" until I buy the desired improvement.

While there is an obvious downside to playing "auto build", there is also an upside. To illustrate this, I submit the city of Tyre. Though it may not look it, this city is in celebration. The 50% bonus for completnig an auto-selectetd improvement applies to all trade across the board. The city is celebrating because luxuries are increased by 50%. Tyre is also generating 50% more research than the light bulb graph indicates.

Click to expand...

I'm definitely missing something here. Is auto boosting your arrows? Are there any other cool things about auto? All I know about it is that it's a way to get around production list overflow.

Tenochtitlan said:

I've been playing this game 20 years and I haven't seen the auto button in probably about 15 years. I play the game without noticing it. I forgot it even existed. I was completely confused when you guys were talking about auto. I must test out the auto thoery valen posted.

Click to expand...

Even when someone last posted in this thread you had been playing for 16 years. Nice!