M4 motorway

The **M4** is a long motorway in the United Kingdom. It goes from London to South Wales. It also passes Bristol. It was first called the **London–South Wales Motorway**.

## Junctions

|scope=col|mile|scope=col|km|scope=col abbr="Eastbound"|Eastbound exits (B carriageway)|scope=col|Junction|scope=col abbr="Westbound"|Westbound exits (A carriageway)|
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|colspan="5"|M4 motorway|||||||||
|7.3|11.8|_Road continues as A4 to Central London_|J1|_Start of motorway_||||||
|8.3 8.5|13.4 13.7|North Circular A406 South Circular A205 Chiswick A315|J2|Staines, Hounslow, Brentford A4||||||
|12.5 12.8|20.1 20.6|_Heston services_|_Services_|_Heston services_||||||
|13.4 13.7|21.5 22.1|Heathrow  (Terminals 4, 5 & Cargo), Hayes, Harrow, Hounslow A312|J3|Heathrow  (Terminals 4, 5 & Cargo), Hayes, Harrow, Hounslow A312||||||
|15.2 15.7|24.5 25.2|Heathrow  (Terminals 2 & 3) (A4) Uxbridge A408|J4a|Heathrow  (Terminals 2 & 3) (A4) Uxbridge A408||||||
|16.8 17.7|27.0 28.5|Heathrow (Terminals 4, 5 & Cargo) , Gatwick Airport , Watford (M3), (M23), (M40), (M1) M25|J4b|Heathrow (Terminals 4, 5&Cargo), Gatwick, Watford (M3), (M23), (M40), (M1), M25||||||
|19.1 19.5|30.7 31.4|Colnbrook, Langley, Slough (East) A4 Eton, Datchet B470|J5|Colnbrook, Langley, Slough (East)  A4, Datchet B470||||||
|22.9 23.2|36.8 37.4|Slough (Central) A355 Windsor A322|J6|Slough (Central) A355 Windsor A322||||||
|24.7 25.0|39.8 40.3|Slough (West) A4|J7|Slough (West) A4||||||
|27.8 28.2|44.7 45.4|High Wycombe, Henley A404(M) Maidenhead A308(M)|J8/9|High Wycombe, Henley A404(M) Maidenhead A308(M)||||||
|35.0 35.8|56.4 57.6|Reading (East), Wokingham, Bracknell A329(M)|J10|Reading (East), Wokingham, Bracknell A329(M)||||||
|40.6 41.2|65.4 66.3|Basingstoke, Reading (Central & South) A33|J11|Basingstoke, Reading (Central & South) A33||||||
|43.5 43.8|70.0 70.5|_Reading services_|_Services_|_Reading services_||||||
|45.3 45.7|72.9 73.5|Reading (West), Theale A4|J12|Reading (West), Theale A4||||||
|56.9 57.2|91.5 92.1|Newbury, Oxford A34 _Chieveley services (Moto)_|J13 _Services_|Newbury, Oxford A34 _Chieveley services (Moto) _||||||
|64.4 64.8|103.7 104.3|Hungerford, Wantage A338|J14|Hungerford, Wantage A338||||||
|68.7|110.5|_Membury services_|_Services_|_Membury services_||||||
|76.4 77.1|122.9 124.0|Swindon (East) A419 Marlborough A346 Oxford (A420)|J15|Swindon A419, Marlborough A346||||||
|82.4 82.8|132.6 133.2|Swindon (West), Royal Wootton Bassett, Wroughton, MoD Lyneham, Calne A3102|J16|Swindon (West), Royal Wootton Bassett, Wroughton, MoD Lyneham, Calne A3102||||||
|94.8 95.3|152.5 153.4|Chippenham A350 Cirencester A429|J17|Chippenham A350 Cirencester A429||||||
|96.7|155.7|_Leigh Delamere services_|_Services_|_Leigh Delamere services_||||||
|104.9 105.6|168.8 170.0|Bath, Stroud A46|J18|Bath, Stroud A46||||||
|112.8 113.2|181.5 182.1|Bristol M32|J19|Bristol M32||||||
|115.8 116.3|186.3 187.2|The SOUTH WEST, Bristol (West), The MIDLANDS, Gloucester, Bristol Airport , M5|J20 _Almondsbury Interchange_|The SOUTH WEST, Bristol (West) M5(S) The MIDLANDS, Gloucester M5(N)||||||
|117.7 189.5|189.5 190.0|No access|J21|Chepstow M48||||||
|121.3 121.6|195.2 195.7|Avonmouth M49|J22|Avonmouth M49||||||
|121.7 124.1|195.9 199.8|_Entry into England_|_Second Severn Crossing_|_Entry into Wales_||||||
|127.0|204.4|_No toll plaza_|_Bridge Toll_|style="background:#dcdcfe;"|_Former Toll plaza (closed Dec 2018)_|||||
|129.2|208.0|Chepstow M48|J23|No access||||||
|131.4 132.2|211.4 212.8|Magor, Caldicot A4810 _Magor services_|J23A _Services_|Magor, Caldicot A4810 _Magor services_||||||
|134.8 135.6|217.0 218.3|City centre A48 Newport (East) B4237 Monmouth A449 The MIDLANDS (M50)|J24|City centre A48 Newport (East) B4237 Monmouth A449||||||
|137.9|222.0|No access|J25|Caerleon B4596||||||
|138.3|222.6|No access|J25A|Newport, Cwmbran A4042||||||
|138.8 139.1|223.4 223.8|_Brynglas Tunnels_|_Tunnel_|_Brynglas Tunnels_||||||
|139.1 139.5|223.8 224.5|Newport, Cwmbran, Caerleon A4051|J26|Newport A4051||||||
|140.8 141,4|226.6 227.6|High Cross B4591|J27|High Cross B4591||||||
|142.0 142.9|228.5 230.0|Newport A48 Risca, Brynmawr A467|J28|Newport A48 Risca, Brynmawr A467||||||
|143.6|231.1|No access|J29|Cardiff (East and South) A48(M)||||||
|146.6 147.3|236.0 237.0|Cardiff (East) A4232 _Cardiff Gate services_|J30 _Services_|Cardiff (East) A4232 _Cardiff Gate services_||||||
|151.9 244.5|244.5 246.1|Merthyr Tydfil, Cardiff A470|J32|Cardiff (North), Merthyr Tydfil A470||||||
|155.4 156.0|250.1 251.1|Cardiff (West), Barry, Penarth A4232 Cardiff Airport _Cardiff West services_|J33 _Services_|Cardiff (West), Barry, Penarth A4232 Cardiff Airport _Cardiff West services_||||||
|157.5 158.1|253.5 254.4|Llantrisant, Rhondda A4119 Royal Glamorgan Hospital|J34|Llantrisant, Rhondda A4119 Royal Glamorgan Hospital||||||
|163.9 164.4|263.7 264.5|Pen-coed A473|J35|Bridgend, Pen-coed A473||||||
|167.5 168.3|269.6 270.8|Bridgend A4061 Maesteg A4063 Princess of Wales Hospital _Sarn Park services_|J36 _Services_|Bridgend A4061 Maesteg A4063 Princess of Wales Hospital _Sarn Park services_||||||
|172.8 173.5|278.1 279.3|Pyle, Porthcawl A4229|J37|Porthcawl, Pyle A4229||||||
|177.0 177.3|284.9 285.3|Port Talbot A48|J38|Port Talbot A48||||||
|178.3|286.9|No access (on-ramp only)|J39|No access||||||
|179.7 179.9|289.2 289.6|Port Talbot A4107|J40|Port Talbot A4107||||||
|180.9 181.3|291.1 291.8|Port Talbot A48|J41|Briton Ferry A48||||||
|183.9 184.9|295.9 297.3|Briton Ferry A48 Swansea (South) A483|J42|Swansea (South) A483||||||
|184.9 185.7|297.5 298.8|Neath, Merthyr Tydfil A465|J43|Neath, Merthyr Tydfil A465||||||
|187.0 187.4|300.9 301.6|Swansea (East) A48|J44|Swansea (East) A48||||||
|188.8 189.3|303.9 304.7|Pontardawe, Swansea (North) A4067|J45|Pontardawe, Swansea (North) A4067||||||
|190.8 191.4|307.0 308.0|Llangyfelach B4489 Felindre Morriston Hospital|J46|Llangyfelach B4489 Felindre Morriston Hospital||||||
|192.4 193.1|309.6 310.7|Swansea (West) A483 Gorseinon A48 _Swansea services_|J47 _Services_|Swansea (West) A483 Gorseinon A48 _Swansea services_||||||
|196.4 197.1|316.0 317.2|Pontarddulais, Llanelli A4138|J48|Pontarddulais, Llanelli A4138||||||
|199.2|320.6|_Start of motorway_|J49 Terminus _Services_|Motorway terminates at a roundabout: Carmarthen A48 Ammanford, Llandeilo A483 Pontarddulais A48 _Pont Abraham services_||||||

## Infobox (road)

- **country**: GBR
- **type**: M
- **route**: 4
- **maint**:
Highways England
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 crossing from England to Wales, 2009
- **length mi**: 189
- **established**: 1963
- **history**: Opened: 1959 (Chiswick Flyover), 1961 (as A4 road (England), A4(M)), 1963, 1966 (as A48(M) motorway, A48(M))
Completed: 1996
- **direction a**: East
- **terminus a**: Chiswick
<small></small>
- **terminus b**: Pont Abraham services, Pont Abraham
<small></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**:
London
London Heathrow Airport
Slough
Maidenhead
Reading, Berkshire, Reading
Newbury, Berkshire, Newbury
Swindon
Bristol
Newport, Wales, Newport
Cardiff
Bridgend
Port Talbot
Neath
Swansea
- **junction**:
J4b → M25 motorway
 /
J8/9 → A308(M) motorway/A404(M) motorway

J10 → A329(M) motorway

J19 → M32 motorway

J20 → M5 motorway

J21 → M48 motorway

J22 → M49 motorway

J23 → M48 motorway

J29 → A48(M) motorway
- **previous type**: M
- **next type**: M
- **previous route**: 3
- **next route**: 5
- **previous dab**: Great Britain