The Central crosses over the Metropolitan and Piccadilly lines' shared Uxbridge branch near West Ruislip depot, and a single track linking the two routes was laid in 1973. The London Borough of Hillingdon has lobbied TfL to divert some or all Central trains along this to Uxbridge, as West Ruislip station is located in a quiet suburb and Uxbridge is a much more densely populated regional centre. TfL has stated that the link will be impossible until the Metropolitan line's signalling is upgraded in 2017.