tunnel under the Mersey was supplemented by a vehicle tunnel in 1934, the Queensway Tunnel. A third tunnel opened in 1971, the Kingsway Tunnel, connecting with the M53 motorway which now runs up the centre of the peninsula. These new roads contributed to the massive growth of commuting by car between Liverpool and the Wirral, and the development of new suburban estates around such villages as Moreton, Upton, Greasby, Pensby, and Bromborough. In 1940–1941, as part of the Blitz, parts of the Wirral, especially around the docks, suffered extensive bomb damage. There were 464 people killed in Birkenhead and 355 in Wallasey, and 80% of all houses in Birkenhead were either destroyed or badly damaged. During the Second World War, the Wirral held two RAF sites, RAF West Kirby (which was a camp, not an airfield) and RAF Hooton Park and a number of anti-aircraft sites to protect the docks of Birkenhead and Liverpool. After the Second World War, economic decline began in the older industries in the area which had started to become known as Merseyside. However, there continued to be industrial development along the Mersey between Birkenhead and Ellesmere Port, including the large Vauxhall Motors car factory on the site of RAF Hooton Park. The 21st century Plans were announced in 2006 for a £4.5bn development around the docklands to be called Wirral Waters. The development is a mixture of industrial, office, residential and leisure facilities. Planning permission was granted in 2010 and work began on the site in 2011, with development work potentially lasting for 30 years. Geography The Wirral can be defined both as a geographical peninsula and as a socio-cultural area. The current Metropolitan Borough of Wirral has a population of 312,293 (according to the 2001 census), and covers an area of , bounded by the Cheshire Plain, the Dee and the Mersey. The Irish Sea lies to its north west side. Geology The peninsula is formed almost wholly from sedimentary bedrock of Triassic age, being sandstone, mudstones and siltstones. Strata exposed at or near the modern surface include the following (in stratigraphic order i.e. uppermost/youngest at top): Mercia Mudstone Group Sidmouth Mudstone Formation Tarporley Siltstone Formation Sherwood Sandstone Group Helsby Sandstone Formation (divided into an upper Frodsham Sandstone Member and a lower Delamere Member in places) Wilmslow Sandstone Formation Chester Pebble Beds Formation Kinnerton Sandstone Formation A small outcrop of Carboniferous rocks occurs around