They started out frozen and quite hard (it was the coldest winter in 50 years) but due to the traffic they oon became quite muddy. The book "Ardennes 1944-Hitler's last gamble in the west" has many pictures some showing Panzer IVs on top of the solid road and another showing a Jeep up to it's hubs. Any feilds that armor manuvered in were quickly torn up because they were not hard packed like the roads, the pics even show some plowed feilds.