WLoop line (railway)
WBarharwa–Azimganj–Katwa loop
WBatasia Loop
WBerlin Ringbahn
WBolshaya Koltsevaya line
WCatford Loop Line
WCircle line (London Underground)
WCircle MRT line
WCity Circle Line
WCity Loop
WExhibition railway line
WGlasgow Subway
WGreater Ring of the Moscow Railway
WHamburg U-Bahn
WHappy Line
WHertford loop line
WHounslow Loop Line
WKA Commuter line Jatinegara–Bogor
WKingston loop line
WKoltsevaya line
WLine 2 (Beijing Subway)
WLine 4 (Shanghai Metro)
WLine 6 (Madrid Metro)
WLine 7 (Chengdu Metro)
WLine 10 (Beijing Subway)
WMeijō Line
WMoscow Central Circle
WMTR Light Rail Routes 705 and 706
WRing Line (Oslo)
WSahibganj loop
WSeoul Subway Line 2
WSutton Loop Line
WThe Loop (CTA)
WToei Ōedo Line
WTyne and Wear Metro
WYamanote Line
WYangon Circular Railway