New York City did a large-scale study of traffic patterns, and concluded ridesharing services brought more people onto the road who otherwise might've stayed home (or taken mass transit).

http://www.schallerconsult.com/rideservices/unsustainable.pd...

Is it possible that the self-driving cars will have the same effect? The rides will be cheaper and more people might want to be on the go.

Traffic in general tends to show a lot of the Jevons paradox.

It would be nice to see Uber/Lyft lead to long-term reductions in the urban land usage of parking lots.

Building more transit, and reducing or removing parking minimums is the way to do this. Unless we do this more people must drive, making more traffic.