Seriously? Just use all the sensors you've got to determine the edges of the road, divide the width of the road in half, and the right-half is the direction you

Seriously? Just use all the sensors you've got to determine the edges of the road, divide the width of the road in half, and the right-half is the direction you're traveling in. Based on the size of this half, determine number of lanes. Create a virtual box so the car stays in the space of where the right-most lane should be. No need to read road markings to stay in lane. edit Nevermind, I forgot that not all roads have an even number of lanes in both directions (even considering single turning lanes and medians). But absent a median or any markings at all, the above is a relatively safe bet. I'm sure they could build a set of heuristics to accommodate the exceptions. Humans have spatial vision, so we should also be able to create cameras that can make out objects floating in free space (such as traffic lights), piece out their components, and compare them to a set of common criteria to determine its intent, the way humans basically do.