I will add that there would have to be some way of keeping those drivers who skid off the road, from going onto the tracks. Every year, with every "first" snowstorm of the winter, there are hundreds of drivers who have to re- learn how to drive in snow.Freeway medians aren't always suitable for reasonably fast intercity trains. See this article about gadgetbahnen that discusses the issues involved. Except in parts of the country where freeways are straight and flat for considerable distances, most freeways have curves that are sharp enough that maximum speeds would be limited. Also, many freeways don't have much of a median strip anymore, was they have used that real estate to add more lanes.