Unlike the Manchester Metrolink, which used heavy rail lines and stations serving the towns around Manchester and street running in Manchester city centre, Merseytram was a stand-alone 100% street running network. Unable to build an underground rail in the city centre after the cancellation of the Picc-Vic tunnel scheme, Greater Manchester designed Metrolink as a mixture of commuter rail and street running trams where because of cost constraints tunnels could not be bored. Unlike Manchester, Liverpool has used and unused tunnels under its city centre. Metrolink acted as a fast commuter rail system on the outskirts and a street running tram in Manchester city centre. Merseytram did not use any Merseyrail track and branch off to disconnected parts of the city not served by rail. Neither did Merseytram use mothballed tunnels or trackbeds in the Liverpool area, of which the city has in abundance. The lack of integration with Merseyrail was criticized.