How can driverless car navigate around a detour? Say for example a road was closed and that information was not known to the car. The car goes to turn on the road but sees construction or road closed signs in the way so it cannot turn. The GPS must recalculate a route somehow, but how does it do that if the car does not know for what distance the road is closed? What would prevent the GPS from trying to go down 1 block and turn onto the road, multiple times over and over until the closed road was no longer closed?

 

Road construction wouldn't be unknown to the car. Apps like Waze and Gramin nav software get constant updates from traffic information services. What makes you think the car wouldn't have that info?

 

^That. Now a tree across the road or something that might be different, but I'm guessing it'll require driver input.

 

In that case, it will see the obstacle and ask the driver to select from several alternate routes.