The Urban Challenge
Driverless vehicles drove through a town among other traffic, obeying rules, negotiating junctions and parking.
Why it matters
The problem changed in kind: a vehicle now had to predict the behaviour of others, not merely see obstacles.
Tartan Racing from Carnegie Mellon, led by William Whittaker, won. The course ran through a closed military base dressed as a town. Compared with the desert an entirely new class of problems appeared: right of way, merging, predicting other agents' intentions. Those remain the hardest problems in autonomous driving today.