what surface type is on runways that are less than or equal to 18.0 in width at ridge landing airpark?
(AND aviation.airport_runway_surface (JOIN aviation.airport_runway_surface.runways (AND (ge aviation.airport_runway.width 18.0^^http://www.w3.org/2001/XMLSchema#float) (JOIN aviation.airport_runway.airport m.04y6l4f))))