Self-driving cars are still learning unwritten road rules, like the Pittsburgh Left

The Pittsburgh Left might be not in the rulebooks, but you better program any self-driving cars driving in the Pennsylvania city with that intel, because it's going to happen. 

Uber is one of several autonomous vehicle companies testing in Pittsburgh that's had to contend with the unwritten rules of the road that can sometimes manifest in aggressive ways. Drivers' tendency in Pittsburgh to turn left before oncoming traffic has a chance to cross the intersection gave this dangerous move its moniker. As a result, Uber now has to train its cars to expect the abrupt left turn.