Researchers from MIT Lincoln Laboratory achieved real-time, nighttime, centimeter-level vehicle localization while driving a test vehicle at highway speeds - over roads whose lane markings were hidden by the snow. The SUV used in the demonstration, held in a mid-March snowstorm of this year, was equipped with their system that employs a novel ground-penetrating radar technique. Many self-localizing vehicles use optical systems to determine their position. The MIT lab developed a sensor that uses very high frequency (VHF) radar reflections of underground features to generate a baseline map of a road's subsurface. This map is generated during a Localizing Ground-Penetrating Radar (LGPR)-equipped vehicle's drive along a roadway and becomes the reference for future travels over that stretch of road. On a revisit, the LGPR mounted beneath the vehicle measures the current reflections of the road's subsurface features, and its algorithm estimates the vehicle's location by comparing those current GPR readings to the baseline map stored in the system's memory. The LGPR's main component is a waterproof closely spaced 12-element antenna array that uses a VHF stepped-frequency continuous wave to penetrate deeper beneath the ground than can typical GPR systems.