M4 motorway

The M4 is a motorway which runs between London and South Wales in the United Kingdom. Major towns and cities along the route include Slough, Reading, Swindon, Bristol, Newport, Cardiff and Swansea. Originally referred to as the London-South Wales Motorway, the English section, including a suspension bridge over the River Severn, was constructed between 1965 and 1971; the Welsh element was completed in 1993. A new Severn bridge, known as the Second Severn Crossing, was opened in 1996 with the M4 rerouted to use it.The M4 runs close to the A4 from London to Bristol. After crossing the River Severn it follows the A48 through South Wales, using the Brynglas Tunnels at Junction 25a, Newport and terminates just north of Pontarddulais. It is one of only three motorways in Wales; the other two, the A48(M) and M48, branch off it. The area of land along the M4, with its towns and cities, is known as the M4 corridor. European route E30 includes most of the M4, although it is not signed as such.