An Expressway is usually a road with a standard less than a motorway. This can be narrower lanes, a missing emergency lane or single level crossings. But always on expressways the access for pedestrians and bicycles is forbidden. This include the ramps like the ramps of motorways. Mostly the roads are signed with a blue or green background with a white car on it.
But these roads need not to be a national road, they can be long distance roads, but they can also only short pieces like bypasses.