When it comes to adopting self-driving cars and trucks, the easiest part may well be building them. The far more difficult task will be maintaining our urban transportation infrastructures for autonomous vehicles to be functional, safe and practical.

Consider that last year, a modified Audi completed a 3,400-mile cross-country trip, driving itself 99% of the time. The 1% of roadway the car couldn’t navigate on its own: construction zones and other complicated traffic situations—hallmarks of urban traffic.

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