They also only work in areas where Google already has &quot;very detailed maps of the roads and terrain&quot;, kind of like invisible train tracks. ( <a href="http:&#x2F;&#x2F;spectrum.ieee.org&#x2F;automaton&#x2F;robotics&#x2F;artificial-intelligence&#x2F;how-google-self-driving-car-works" rel="nofollow">http:&#x2F;&#x2F;spectrum.ieee.org&#x2F;automaton&#x2F;robotics&#x2F;artificial-intel...</a> )