I drove to and from Lake District this weekend and there was a road with a sign that restricts it to only 'light vehicles and motorcycles' as well as no tracffic at all in winter conditons. It was a 30%/1:3 gradient and in perfect conditions my front wheels were slipping going up the slope. Any heavier cars may struggle, especially if it rains. There should be an option to avoid these sort of roads or for editors to atleast be able to add permanent hazards.