SimCity update 7.0 is scheduled to arrive in a city near you (that you created) in August, and it's bringing some traffic updates along for the ride. Update 7.0 adds the ability to raise and lower roads to build bridges and tunnels, as demonstrated by Lead Gameplay Scripter Guillaume Pierre.
The update also allows players to plant trees. This mechanic is inspired by a mod, and includes three tree types that grow roadside and four that can flourish anywhere, Pierre says in a series of tweets. The greenery joins asphalt-based operations improvements outlined by Software Engineer (and Captain?) Alexander Harkness in a recent SimCity blog post.