Can they perceive where on the road they should be located when the road is totally covered in snow and you can't see the pavement, let alone the line markets, possibly only tire tracks, if that?
Yes. An autonomous vehicle with lidar and maps can locate itself using any landmark, or series of landmarks it can see, it isn't limited to lane markings.
Just think, the remains of the last self-driving car will help the next self-driving car avoid the trap. But only if Google carefully catalogs it and no one moves the wreckage.
You can't reliably know the distance from pavement to any of those things unless you plan on indexing every physical object along every roadway.
I think the most likely scenario is self driving cars won't drive in those conditions, hopefully those conditions don't develop while you're on the roadways or you'll be parked somewhere cold.
They do index everything, the maps they rely on are lidar generated 3D point cloud fields that make a model of everything around the road, and are frequently updated.
