Rapid transit in the United Kingdom consists of four systems: the London Underground and the Docklands Light Railway in London; the Tyne and Wear Metro in Tyne and Wear; and the Glasgow Subway. The term may also include commuter rail systems with aspects of rapid transit such as the London Overground and Elizabeth line in London, and Merseyrail in the Liverpool City Region. Rapid transit has also been proposed in other UK cities including Sheffield, Manchester, Leeds, Birmingham, Cardiff, Bristol, and Cambridge.