Caravan pathfinding

[Ansive]

While playing with caravan range to get the Silk Road achievement I noticed a few interesting things.

- roads extend caravan range by 2. (tiles cost 0.5 movement, with 10 range you can reach 14 tiles away by building 8 roads).
- unlike units, caravans do not get 0.33 moment cost on roads when teching machinery
- not sure what railroad does to caravans
- all tiles without a road cost 1 movement
- caravans can use foreign roads, even without open borders
- caravans will not detour to follow roads, they take the direct path, you need to plan your roads with that in mind
- you can reach more distant cities by building roads in foreign lands without any maintenance cost to you

So if you have a range 10 caravan and two cities 18 tiles away and a road that is one tile higher or lower than the cities (for whatever reason) the caravan will no be able to connect to the cities. This is because the caravan would take the direct path between the cities, it will not go higher or lower unless restricted by the terrain.

Main point is, caravans will only follow roads if they do not detour.

Not sure if caravans will follow the road when there are multiple direct paths. (for example 2 cities, one of them 3 tiles higher, giving you the choice of when to lead the road higher). But I presume the caravan will follow the road.

 

[Solutionfinder]

Thanks for info. I never understood the exact mehanics for caravans. I prefer cargo ships but yes sometimes that is not an option.

 

[Volcanon]

Thanks for info. I never understood the exact mehanics for caravans. I prefer cargo ships but yes sometimes that is not an option.

Cargo Ships are scientifically engineered to always go near barbarian camps.

 

[Solutionfinder]

Cargo Ships are scientifically engineered to always go near barbarian camps.

lol, so you make sure there is no camp nearby. I protect my Cargo ships at all costs, even prefer a close route to a CS over a same amount of gold route to AI, unless it has a really high science bonus.

 

[danaphanous]

I had an archipelago game where France had some really nice trading cities farther away then any others! I sent several ships to him from the renaissance through the industrial and every time within a few turns a barb would kill the route. The guy literally left a camp 10 hexes from his capital on the forward, unsettled part of his own continent. Like all game. This was on immortal! AI can never be counted on to protect their own lands or routes so scout first before you send your trade routes unless it is clearly only water along the way!

I think it'd be funny to do this purposefully to the AI sometime as venice. Never trade in one direction and leave a barb encampment over on that side. AI on that side will be sending you routes all game (esp. if you are ahead on science) and losing them all game for wasted hammers. You can blockade your city so they don't get close to venice and they only mess with foreign trade routes.

Some more points:
- railroad does extend land routes further
- caravans take rough movement cost (hills/forests) and have to navigate around mountains but no river crossing penalty it seems

For this reason it can be advantageous to build roads through bordering CS and whack all the forests down. It will extend their range. Caravansary also extends range by 50%