I skated a freeway once a few years ago, but it was on i-70 driving back to denver from the mountains. They have to close the Eisenhower tunnel for like a half hour when traffic is bad to make sure people don't die from car fumes while driving through it. When it happens you just know that you won't be moving for awhile, so I took out my rainy day board and skated a bit between the cars. It was a solid way to pass the time.