railway arches, making the cost of any station construction prohibitive. Liverpool Street station services On 31 May 2015 the Liverpool Street to Enfield Town, Cheshunt (via Seven Sisters) and Chingford services, as well as the Romford to Upminster service, were transferred from Greater Anglia to TfL to become part of the London Overground network. Network Introduction The initial network, service levels and timetables were a continuation of Silverlink Metro services, a set of routes primarily built and electrified by the North London and London & North Western railway companies in the 19th and early 20th centuries. As the Overground name implies, the majority of the network is above ground, and it mostly consists of railway lines that connect areas outside Central London, with a considerable portion of the network in Zone 2. The network also uses in central London, the southern terminus of the Watford DC line. The network interchanges with the Bakerloo, Central, District, Hammersmith & City, Jubilee, Northern, Circle, Metropolitan and Victoria tube lines, and also with the Docklands Light Railway, Tramlink and Elizabeth line networks. The Overground lines appear on Tube maps issued by TfL, and a separate map of the system is available. Much of London Overground passes through less affluent areas, and is seen as contributing to their regeneration. The North London and Gospel Oak to Barking lines were previously considered by the Transport Committee of the London Assembly to be neglected and not developed to their full potential. Services , the typical off-peak service pattern is: Battersea Park railway station is served by an infrequent parliamentary train service from , which terminates at Battersea Park instead of . Since the reorganization of services into the London Overground network, this has been the only service to use the link from platform 2 at Battersea Park to . Depots Highbury & Islington to New Cross, Clapham Junction, Crystal Palace and West Croydon services are served by New Cross Gate TMD. Richmond and Clapham Junction to Stratford, Watford Junction to Euston, and Gospel Oak to Barking services are served by Willesden TMD. London Liverpool Street to Enfield Town, Cheshunt and Chingford, and Romford to Upminster are served by Ilford EMU Depot, Chingford sidings and Gidea Park Sidings. Operations London Overground's head office and control centre are at Swiss Cottage. Rolling stock is maintained at Willesden Junction and New Cross Gate TMDs, the latter being newly built for