M4 corridor bridge, serving Chepstow, being renumbered the M48, although the area is still generally considered as falling within the M4 corridor. Since the start of the 21st Century there has been evidence of more investment west of Cardiff, such as: M4 corridor The M4 corridor is an area in the United Kingdom adjacent to the M4 motorway, which runs from London to South Wales. It is a major high-technology hub. Important cities and towns linked by the M4 include (from east to west) London, Slough, Bracknell, Maidenhead, Reading, Newbury, Swindon, Bath, Bristol, Newport, Cardiff, and Swansea. The area is also served
M4 (Copenhagen) M4 (Copenhagen) The M4 (the Harbour Line) is a future expansion of the Copenhagen Metro connecting Nordhavn in the north with Sydhavn in the south. The northern arm was approved by the Danish Parliament in 2012 and is expected to open in 2019, while the southern arm was approved in 2015 and is expected to open in 2023. Both Nordhavn and Sydhavn are former industrial areas situated at opposite ends of the Port of Copenhagen and currently undergoing urban renewal under the auspices of By & Havn. The M4 Line will serve 13 stations. From København H to Østerport the