For the patent to work, a vehicle would need a front-mounted camera and a radar transmitter with at least an antenna at the rear. When a safety problem is spotted, like an obstruction in the road, the system would begin recording and tag the clip with metadata, like size, distance, and whether or not the object is moving. All of that information would then be broadcast to other cars nearby. With each vehicle transferring the data individually, as long as other drivers are close enough, everyone in the network gets the advisory.
Conceivably, this tech could make passing on a two-lane road safer, as well. In the patent, Google describes giving drivers the ability to look far ahead in front of traffic "thereby obtaining an 'x-ray like' vision capability of seeing beyond a blockade of leading vehicles."