Paradox has announced a Mass Transit expansion for the PC, Mac, and Linux versions of Cities: Skylines that helps citizens get around the city by land, sea, and air.
Adding infrastructure transit features such as cable cars, monorails, ferries, and blimps, not only helps your citizens, but also generates wealth for your town.
Of course, with the new transportation systems (along with hubs to combine these services, new road types, etc.) comes additional traffic challenge scenarios.
Like previous expansions, at the same time as Mass Transit releases (which Paradox says will be "soon") a free update will also come out, and this adds traffic-related features such as emergency vehicle overtaking, a larger public transportation budget, and the ability to name roads.