London Underground ticketing destinations and most interchange stations are in zone 1, meaning that most journeys over similar distances will cost the same. A few stations in the north east of the network, on the Central line, outside Greater London (in the Epping Forest district) are in zones 4, 5 and 6. In the north west of the network, on the Metropolitan line, zones 7, 8 and 9 (formerly A - D) cover stations outside Greater London including Amersham and Chesham in the Chiltern district of Buckinghamshire. Unlike the lower numbered zones, these ancillary areas do not encircle the capital. Some stations are
London City Airport North Circular Road (A406). Also the A13 provides easy access to the M25 motorway, as with the A406 connecting to the M11 motorway. The airport has both a short-term and a long-term car park, both within walking distance of the terminal and a taxi rank outside the terminal door. The airport is served by London Buses services: The express shuttle buses, which formerly ran to various destinations, were withdrawn after the DLR line was built. Until 2006, Silvertown railway station on the North London line served the airport, but it was closed during the construction of Crossrail. When the new