From the article, "Yes, this requires pre-mapping, but so does lidar. And WaveSense says that remapping should be far less frequent as conditions under the road

From the article, "Yes, this requires pre-mapping, but so does lidar. And WaveSense says that remapping should be far less frequent as conditions under the road are less subject to change than they are above ground." I don't know that I agree with this statement given that this technology is meant to operate specifically in cold weather climates. I live in Montana, which is, of course, rather cold in the winter. We get frost heaving every spring when temperatures begin to rise. Frost heaving is caused by the formation of ice lenses in the soil below the road. Ice lenses form when water is drawn via capillary action to the same level as frost depth. The water then freezes. Frozen water acts like a solid and can them draw more water in via further capillary action thus increasing the size of the lenses. The ground penetrating radar will be able to see these lenses. In an urban environment, this will likely be less of an issue. However, in a rural setting where there is less built environment to reference, it may cause some issues. I am sure those working on this technology have though of these issues and will be able to filter out the noise that subsurface water/ice will create. I just feel it is disingenuous to think that the subsurface world is static. Ultimately, more sensors using different detection methods will help to improve the operation of autonomous vehicles. Edit: added a few words to clarify a thought.