03-11-2013 11:15 PM - edited 03-11-2013 11:15 PM
You can not. Sometimes, they will automatically be built, but there is currently no way to do this.
Given that this was a basic feature in all previous SimCities, and is even further expanded upon in other games, I suspect it will be part of a pay-for-it/DLC feature in the future.
03-11-2013 11:27 PM
Bridges are built automatically as you drag out the road across water. They are more expensive, so make sure you have enough cash. Bridges need go start and stop on land, and are continuous (no intersections over water)
Other factors can prevent a bridge from beiing placed, such as if there is a placed building nearby and there isnt enough room to modify the land to support the ramps up to the bridge.