All you coders out there say it with me: &quot;cost function&quot;.<p>Really, is that so hard?  I see a lot of comments about what is going to happen when robotic cars do this.  Well, every roboticist I know, and I know a big bunch of them, is well acquainted with the concept of having a cost-map overlay on the world map.  And it is not only OK, but common, to have infinite cost assigned to many nodes -- &quot;Don&#x27;t go there robot, you will not be a happy robot.&quot;<p>So why does the GPS database have poorly assigned cost values on certain road segments?  Perhaps because QA de-prioritizes little-traveled roads?<p>But more to the point -- I&#x27;ll get out of roboticist mode and into seasoned backwoods traveler mode for a moment -- don&#x27;t go where you are not prepared to go.  Look at a paper map, ask a local at the gas station about conditions, and if the road ends up bruising your kidneys, turn back.