It&#x27;s not that usual for large projects to proceed a fair distance before seemingly obvious problems become apparent. Bridges that fail to meet in the center come to mind.<p>I remember being at a meeting talking about the implementation of a chipset where each of the three chips required another chip to be running first. Global conditions can be more obvious to an outsider than those involved in many details of creating X big plan.<p><i>Why would a snow bank not be avoidable as well?</i><p>The Google car in particular is intended to follow a pre-defined path derived from more-detailed-version of Google Maps with obstacle avoidance being just deviations from that pre-defined plan. It seems like the situation described by the op, the road-structure itself changing, would present significant obstacles to that strategy. Essentially, rather than solving the problem of guiding a vehicle down the road using visible spectrum image-processing, Google avoided the problem by various stands-in; lidar for obstacles and satellite maps for positioning. Clever but that sort of thing will have failures that might be surprising - and surprisingly obvious.