To form the maps, radar signals transmitted by driving cars are used to collect billions of reflection points bouncing off of surrounding structures like road signs and lane dividers. The radar data are then transmitted to a cloud-based server and integrated into a TomTom mapping system, which is then made available to cars on the road. According to Bosch, automated vehicles can use the radar-based map to pinpoint their lane location to within a few centimeters; the first data collection vehicles are expected to hit roads by 2020, starting in Europe and the US.
There are some advantages to radar road signature. For instance, video-based mapping systems can be hampered by low light or weather. And while video files tend to be quite large, the radar data require much less bandwidth to transmit.
But video mapping and LiDAR are pretty reliable. And Sony has even introduced an HDR camera that does rather well in the dark. It may turn out that radar-based systems like this one become more useful when used alongside video-based data, boosting sensing robustness from multiple vantages. So, while radar road signature is certainly an interesting addition to road-sensing technology, whether it's better remains to be seen.