March 9, 2016, Governing.com -- The storm that rolled through Ann Arbor, Mich., in late November brought nine inches of snow and an experimental opportunity too good to pass up. A team of Ford engineers working to develop self-driving vehicles decided it would be a good time to put their modified Ford Fusion sedans to the test.

Snow, like rain, can be especially tricky for automated vehicles. Precipitation makes it harder for driverless cars to know where they are. Their cameras can’t see lines on snow-covered pavement or in the reflections of puddles. Falling precipitation interferes with radar. Piles of snow make finding the curbs and road edges harder, even for the cars’ laser-powered mapping devices. On top of that, snow is something of a novelty for self-driving cars. Most of them have been confined to sunny locales in states like California, Nevada and Texas, where rain and snow are rarer.

So the Ford team jumped at the chance to test their vehicles in the Michigan winter. Rather than heading to Ford’s proving grounds in Dearborn, they went to Mcity, a 32-acre test track in north Ann Arbor. It’s a shared track that’s operated by the University of Michigan and used by automakers and the state transportation department to try out autonomous and connected cars. Mcity includes elements you wouldn’t expect to find on most test tracks, things like stoplights that broadcast information to vehicles, a railroad crossing, a bus stop, highway on-ramps and gantries, a small hill, gravel roads, sidewalk crossings, stop signs, a simulated tree canopy and overpass, roundabouts, vandalized traffic signs, and a mockup of downtown city blocks.