What is M4 motorway?
{{infobox road | country=GBR | type=M | route=4 | maint = <br>[[Highways England]]<br>[[South Wales]] Trunk Road Agent | map= M4 motorway (Great Britain) map.svg | photo= New Severn Bridge - panoramio.jpg | photo_notes= [[Prince of Wales Bridge (United Kingdom)|Prince of Wales Bridge]] looking towards [[Wales]] | length_mi=189 | length_ref=<ref>{{cite web|title=Directions to M4, Hendy, Swansea|url=https://www.google.co.uk/maps/dir/51.4898069,-0.2785522/51.7451923,-4.0654193/@51.8830984,-3.2464218,243942m/am=t/data=!3m2!1e3!4b1?hl=en|publisher=[[Google]]|accessdate=11 February 2017}}</ref> | established= 1963 | history=Opened: 1959 ([[Chiswick Flyover]]), 1961 (as [[A4 road (England)|A4]](M)), 1963, 1966 (as [[A48(M) motorway|A48(M)]])<br>Completed: 1996 | direction_a= East | terminus_a= [[Chiswick]]<br><small>{{coord|51.4897|-0.2781|type:landmark_region:GB|display=inline|name=M4 motorway (eastern end)}}</small> | terminus_b= [[Pont Abraham services|Pont Abraham]]<br><small>{{coord|51.7451|-4.0651|type:landmark_region:GB|display=inline|name=M4 motorway (western end)}}</small> | counties= [[Greater London]], [[Berkshire]], [[Wiltshire]], [[Gloucestershire]], [[Monmouthshire]], [[Newport, Wales|Newport]], [[Cardiff]], [[Vale of Glamorgan]], [[Rhondda Cynon Taf]], [[Bridgend County Borough|Bridgend]], [[Neath Port Talbot]], [[Swansea]], [[Carmarthenshire]] | destinations= <br />[[London]]<br />[[London Heathrow Airport]]<br />[[Slough]]<br />[[Maidenhead]]<br />[[Reading, Berkshire|Reading]]<br />[[Newbury, Berkshire|Newbury]]<br />[[Swindon]]<br />[[Bristol]]<br />[[Newport, Wales|Newport]]<br />[[Cardiff]]<br />[[Bridgend]]<br />[[Port Talbot]]<br />[[Neath]]<br />[[Swansea]] | e-road= {{BAB-E|30}} | junction= [[File:Junction 4b.svg|1000x20px]] [[File:UK-Motorway-M25.svg|1000x20px]]<br>J4b → [[M25 motorway]]<br>[[File:Junction 8-9.svg|1000x20px]] [[File:UK-Motorway-A308 (M).svg|1000x20px]]/[[File:UK-Motorway-A404 (M).svg|1000x20px]]<br>J8/9 → [[A308(M) motorway]]/[[A404(M) motorway]]<br>[[File:Junction 10.svg|1000x