Castle Bar Park railway station is in the London Borough of Ealing in west London, England and is in Travelcard Zone 4. It is on the Greenford branch line, 78 chains (1.6 km) down the line from West Ealing and 7 miles 44 chains (12.2 km) measured from London Paddington. The station and all trains serving it are operated by Great Western Railway. When opened in 1904, it was called Castle Bar Park Halt. As of October 2008, Oyster "pay as you go" can be used for journeys originating or ending at Castle Bar Park.