Civilization 5 – Does Jungle Block Line of Sight

To directly answer the question, road maintenance is listed as "Tile Improvement Maintenance", when you mouse over your treasury/income in the top left. You can see a circled example in the screenshot below. As for the details:

Roads cost to maintain both inside and outside your borders

Because my conclusions are contrary to previous info we had about road maintenance in neutral territory... Pics Or It Didn't Happen!

Exibit 1: Prince Difficulty, some roads in, some out.

As you can see, I have 4 roads in my territory, and one outside, costing me a total of 5 maintenance. I have no other roads anywhere else. I wish I had taken a screenshot of the previous turn. The next time I find myself in this situation, I'll take a pair of screenshots and replace this single picture. Either way, remember you can always try it yourself to be sure. YaY Science!

Exibit 2: Settler Difficulty, all roads out.

Thanks to @DMA57361's questions, I checked a different difficulty and a different number of roads outside the borders, namely all of them. On Settler difficulty, building roads only outside of my borders, I still ended up with maintenance for the roads, so clearly they do cost.

Edited to account for difficulty, now that I've completed more extensive testing.

Roads cost the same to maintain in your own territory, and in neutral territory. How much varies by difficulty:

Road Maintenance /Road/Turn
Difficulty | Your Land | Neutral
-----------|-----------|--------
Settler    |    0.34g  |  0.34g
Chieftain  |    0.50g  |  0.50g
Warlord    |    0.75g  |  0.75g
Prince     |    1.00g  |  1.00g
5-7*       |    1.00g  |  1.00g
Deity      |    1.00g  |  1.00g

Road maintenance is only ever a whole number. In case of decimal remainder, always round down. For example, on Settler, 2 roads cost 0.68, which clearly got rounded down to 0.

To find each of these, I built roads either only inside, or only outside my borders at a time. This confirmed the same results for inside and out, but got me only close numbers. Then @Oak used his powers of XML scrying, and found the exact numbers for us.

Since so many difficulties are 1g, (and the ones that are not are the easier difficulties anyway,) and for our general happiness, I hereby declare "1g" an acceptable approximation for all further calculations relating to road maintenance. Hurray!

When next I can test, I'll re-test road's in another nation's borders, to clean up the next section! Same Bat-time. Same Bat-channel.

Roads DO NOT cost to maintain inside another nation's borders

Edit: This section is suspect until I complete further testing, since one road did not cause me maintenance. My mistake for not setting up a proper control. This still may be completely true, but I need to test on different difficulties and compare with similar numbers of roads in my borders and in neutral territory.

In the game these two pictures originated from, I had no roads, and built a road inside each another civilization's borders, and a city-state's borders. I can't verify that they were costing any gold to the land's owner (Rome's income was fluctuating quite a bit), but I can say for sure they were costing me nothing. This is likely what bwarner saw that caused the error.

There may be other effects that change which roads cost to maintain, but these seem to be the major ones. Anyone found anything not explained by these.

PS As with any screenshot heavy post, I do my best to crop/scale the images to reasonable sizes without losing the important parts, such as the circled text. They still end up crowding the page, for which I'm sorry.

Here is a list of all the effects from happiness level that I could find. To answer your specific question, most of the effects care only if your civilization is happy or unhappy, by one :) or :(. (I believe zero :) is fine.) But there are three effects that care about the amount your civilization is happy or unhappy:

• VERY unhappy occurs when you hit -10 happiness. (Thank you @Oak)
• Golden Age points accumulate (or deplete) equal to the amount your civilization is happy (or unhappy)
• Piety->Mandate of Heaven uses your exact excess happyness to calculate how much culture you get.

Full list of effects:

Happy

• Growth: Cities grow normally.
• Golden Ages: If you have excess happiness, each turn it accumulates into Golden Age points, and when you have enough, your civilization enters a Golden Age. After the golden age the process starts again, although I believe you need more Golden Age points for each subsequent Golden Age.

Unhappy

• Growth: Cities grow at 1/4 speed when your population is unhappy.
• Golden Ages: The amout your civilization is unhappy is subtracted from the Golden Age points.

VERY unhappy

• Growth: Cities do not grow.
• Units: Settlers may not be trained.
• Production: Cities generate -50% production.
• Unit are less effective in combat. They get -33% combat strength.

VERY VERY unhappy (-20 or lower)

• Rebels will spawn in your border and attack your city

Social Policies

• Piety->Mandate of Heaven allows you to add 50% of your excess happiness to your culture each turn.
• Rationalism->Sovereignty boosts science +15% when your empire is happy.
• There are numerous social policies that affect the happiness level, but these are the ones that get effect from the happiness level.

Sources:

• General info: mousing over the happiness listing on the top bar, left side, during various happy states.
• Golden age info: mousing over the golden age display on the top bar, left side, during various happy states.
• Combat info: Comparing happy (normal) combat strength to VERY unhappy combat strength, by mousing over an enemy unit. The VERY unhappy combat modifier is clearly listed in the calculations.
• Production info: mousing over a city's production listing in the top left when VERY unhappy.
• Social Policy info: The social policy screen, accessible by clicking on the culture listing on the top bar, left side.