Brave New World Featurette 3: Trade Routes
http://www.youtube.com/watch?v=J7hEiMiOzosInternational Trade Routes replace the extra gold previously earned from working river or coast tiles. You can now build special Trade Units such as the Caravan and Cargo Ship, and set them up so that they automatically follow a route back and forth between two cities. You start the game with two available routes, and more can be unlocked as the game progresses (typically at least seven or eight by the end of the game). Certain technologies, Wonders and civilization Unique Abilities increase the available number of International Trade Routes.
Note that the existing Trade Routes formed by road and rail connections to the Capital appear to still exist. Hence the "International" designation of the new Trade Route system. Dennis mentioned that these old trade routes are now called "City Connections."

- bnw_trade_route_ui.jpg (233.57 KiB) Viewed 28078 times
Clicking on a Trade Unit in a city brings up a list of possible routes for that unit type from that city. Trade with one of your own cities can transfer food (if you have a Granary) or production (if you have a Workshop). Food or Production from an internal Trade Route are bonus; they are not drained from the source city's own output. Trade with a foreign city brings gold to both parties, the amount of which depends on a number of factors. Sea routes appear to be twice as lucrative as land routes (with an explicit "2x" modifier). Trade routes from cities next to a river gain +25% Gold. The per-turn gold value of the Trade Route increases with the distance of the route, the difference in local resources between the two cities, and the existence of Markets and other trade-related buildings in your city. In addition to gold, trade routes can also transmit religion, and cultural influence, and this transmission can go both ways. Trade with a partner who is ahead of you in technology can yield science for you. Trade Routes generate a positive diplomatic modifier with the trading partner.

Trade Routes last for 30 turns (on Standard game speed), after with the unit will ask to be reassigned, but it appears that the route can be manually cancelled at any time. The Trade Units operating the trade routes can be attacked, allowing you to disrupt other civilization's trade routes if you go to war with them. This also means your own trade routes must be protected from barbarians and enemy civilizations. There will be a player-toggled map overlay displaying trade routes ... A city may have more than one trade route.
Ed Beach: "Although both parties gain gold from the route, the civilization that the trade route originates from gets a larger sum of gold than the destination civilization. Additionally, other systems hitch a ride on trade routes, like religious pressure, science (science can be gained from more advanced civilization this way), Tourism bonuses, and more. Trade routes can also be created between two cities of the same civilization. Once the origin city has a Granary, it can send food to the destination city, and once it has a Workshop it can send production. This can be powerful if you have a new city that needs to be “pumped up”, or a city that’s constructing a Wonder that could use a production bump.
"A lucrative trade route is going to give you a positive modifier to your relationship with that partner, and if you’re spreading religion then you’re likely to see a benefit from that as well.
"In general, the Trade Route system rewards you for connecting two cities that have very different local resources. So, it lists which local resources are found in one city and not another, and the more of those you have the more gold you'll get out of the trade route."
http://well-of-souls.com/civ/civ5_brave ... ade_routesOther interesting information:
Ideologies
It is possible to change Ideologies, but not when your people are content (see Public Opinion, below).
If you are the one of the first two civilizations to adopt a particular Ideology, you will be awarded one or two free "Early Adopter" tenets.
Ed Beach: "The different victory types are allied with Ideologies. So each Ideology is good at three out of the four victory types. If I'm going for a Space Race victory, for instance, I have to go either Freedom or Order. I have to go either the Soviet space model or the US space model."
The Ed Beach quote above comes from
this dev walkthrough. Note that this apparently is a
hard "have to". You
must be in Freedom or Order to win in the Space Race; it is not merely inefficient or more difficult to do so through Autocracy. And this ideology-dependence extends to the other victory types as well.
This post from a thread on Reddit points out that BNW's Steam achievements do not credit a Technological Victory through Autocracy, a Diplomacy Victory through Order, or a Domination Victory through Freedom. So no fascist space launches, communist United Nations leadership, or freedom-loving world domination.
Public Opinion
There is a new status for each civilization linked to Ideology called Public Opinion, which is displayed in the Culture Victory tab of the Culture Overview dialog. It measures a civilizations' satisfaction with their current Ideology choice. If another civilization with a different ideology begins to overwhelm your culture with their tourism, then your Public Opinion will begin to decline. Possible value are Content, Dissidents, Civil Resistance, and Revolutionary Wave. Some level of Unhappiness will be generated if this satisfaction level is anything other than Content. At an overall Happiness level of -20 or below the civilization will start to lose cities to revolt and may change the public's Preferred Ideology (you can find that preference in the Public Opinion tooltip). If this situation becomes bad enough, you may have to switch Ideologies to placate your public. This would presumably mean losing access to the Tenets that you have purchased. It's not currently clear what "revolt" means specifically, whether cities go into a state of anarchy, or whether they actually change allegiance to another civilization.
Dennis Shirk: "If I choose say, Order, and you’re Freedom, and I’m generating all this Tourism, my influence is going to start pressing on your empire and your people are going to start getting unhappy. If you let it go on too long, you basically have to either declare war on me or switch to my ideology. Your cities might start flipping to my civilization if they riot too much."
http://well-of-souls.com/civ/civ5_brave ... re_victory

- Box art with triptych showing off the ideologies. Civ V on the television screens and microphone in the Freedom panel is a cute touch.