man-made tunnel A tunnel constructed by human means. ENVO ENVO:00000066 FTT:1136 FTT:1184 FTT:396 FTT:397 Geonames:R.TNL Geonames:R.TNLRD Geonames:R.TNLRR Geonames:R.TNLS TGN:51845 Wikipedia:Tunnel canal tunnel railroad tunnel road tunnel tunnel tunnels underpass tunnel