Microwaves heat things, right? So what if you could melt snow and ice with a Microwaving Truck? Maybe add something to the roads, like capsules or metal particles, to make the microwaves more effective. Suppose, in snow country, all vehicles had them. Then, after melting their own driveways, all the cars would help with the melting. Adding particles to roads sounds easier and cheaper than embedding any kind of heating-coil system.