Is it worth connecting my cities with roads early in Civ 5?
There are two basic reasons to connect your cities by roads: for Trade Route income, and for Unit movement
Connecting for Trade Routes
Warning! These calculations are now suspect because of new info found about how road maintenance works. I will update this with any changes needed once we have verified numbers for road maintenance costs.
Summary: only build trade routes to cities with 6 population or more. If you care for the math, then continue reading...
Now that Oak has solved the Trade Route formula for us, we know that normal trade income is very close to 1.25 * population of the connected city. (not the capital)
So, suppose you have your capital and one city, they are separated by 6 hexes. You'll be paying to maintain each of those roads, costing you 6g. So, at a population of 3, you would make 3.75g, be spending 6g, and be losing money overall. Your worker time is EASILY spent doing something else. Of course, if your cities are closer together, the calculations look better. Finally, I believe that Harbors cost 2g to maintain. Realizing that you only pay for your capital harbor once, sea routes effectively only cost 2g to maintain.
Population | Income | Net Income with...| Harbor/ | | | 6 Roads | 4 Roads | 2 Roads | 3 | 3.75g | -2.25g | -.25g | 1.75g | 4 | 5.00g | -1.00g | 1.00g | 3.00g | 5 | 6.25g | 0.25g | 2.25g | 4.25g | 6 | 7.50g | 1.50g | 3.50g | 5.50g |
I would like to propose a rule of thumb. You can pick whichever population number seems best to you, but I believe my worker can do better than even a 4g improvement by working other tiles in the time it would have taken him to build that road. Thus:
Only build trade routes to cities with 6 population or more.
If you follow this rule of thumb, you will, at the least, never lose money on a trade route. Further, if you start working on the trade route when the city is size 6 already, there's a good chance it will have grown to 7 at least by the time you finish, and you can actually start making enough money for that worker time to be worth it.
Final note on trade routes: Arabia gets a flat +1 to trade route income. (AFTER the multiplier, so simply add 1 to every gold number on the chart.) So feel free connect Arabian cities at population 5 or more, if you like.
Connecting for Unit Movement
We don't have nearly as good of data on this, but from my Civilization experiences, roads are VERY worth building if you are producing units and sending them to war. You get your best units at the front for longer before they are obsolete, and you'll have more units at the front at any given time.
If you're not moving units for war, roads may also be worth building to quickly move defenders in the event of being attacked, by barbarians or another Civ. I think you can just ask yourself:
- Am I likely to be attacked in that city?
- Is the attack likely to beat the city?
- Do you HAVE units that could get there by the road to defend?
If any of those it no, the road is not worth it, cause it won't help.
And if you're not at war, and not defending, I doubt you want to build roads just to move units, because you don't sound like you're moving units around much at all!
I just got a devious thought -- can I get open borders with an AI, spam roads in their territory, and empty their gold reserves? >:D
@Raven I don't know, but the idea certainly amuses me. :) That seems like it almost deserves its own question. If not, I think the question on road maintenance might be a better place to clarify that.
@Raven draining the coffers of AI civilizations is not necessarily good - it means they have less money available to give you when you trade with them / beat them into submission.
@Raven - I thought that the builder of the road pays for the upkeep. At least, that is what I have read elsewhere. It begs the question what happens when you conquer a city (do you adopt those roads)?
@CJM It seems to be based on cultural borderrs. see the question on road maintenance I linked in my first comment for details.
I'll just add that roads can also save money on defense: If a road lets your military move between two cities in a single turn, you can have one unit defending two or three cities instead of one unit per city, saving 1-5 gold per unit. Workers also become more efficient, as they spend less time moving around and more time building things.