Map of M4 Motorway Junctions
Map of the M4 motorway junctions.
West M4
To the West the M4 joins the M5 at M4 Junction 20 which heads north to Devon Cornwall and the South West of England.
The Western end of the M4 is in South Wales Junctions 23 to 48. Bridgend is on Junctions 25 to 37, M4 Junctions 44 and 45 for Swansea, Junctions 30 to 33 for Cardiff and Junctions 24 to 28 for Newport.
East M4
At the eastern end of the M4 is London, with Junctions for Slough, Reading, Newbury, Swindon and Bristol on the way to Wales in the West.
How Do I Find M4 Traffic News?
Simply type the search words in the search facility towards the top right of this page and click "search".
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Latest accident or incident on the M4
The most recent accident or incident on the M4 that we are aware of.
Latest active roadworks on the M4
Roadworks live on the M4 right now.
M4 eastbound Jct 18 to Jct 17 lane closure 154/2-152/5
04:2427 Aug 2026reported 18 min ago
- Location
- M4 eastbound between J18 and J17
- Direction
- Eastbound
- Lanes closed
- Lane closures
- Reason
- Maintenance work
- Schedule
- 19:48 Wed 26 Aug → 06:00 Thu 27 Aug
+ 2 more active roadworks - search all M4 traffic news →
Latest planned roadworks on the M4
The next planned roadworks scheduled on the M4.
M4 eastbound Jct 12 exit slip lane 1 closure
04:2427 Aug 2026reported 18 min ago
- Location
- M4 J12 eastbound exit
- Direction
- Eastbound
- Lanes closed
- Slip road closed
- Reason
- Road improvement or upgrading
- Schedule
- 20:00 Thu 27 Aug → 06:00 Fri 28 Aug
Forecast - not confirmed
+ 11 more planned roadworks - search all M4 traffic news →
Search all the latest M4 traffic news →
Updated 04:42 Thu 27 Aug
Powered by National Highways’ Transport Data Feeds.
M4 junctions — west to east
▲ WEST South Wales & Pont Abraham
- J49A48/A483Pont Abraham — M4 ends (for Llanelli, Ammanford)
- J48A4138Hendy, Llanelli, Pontarddulais
- J47A48Penllergaer, Gorseinon, Swansea (west)
- J46A48Llangyfelach, Morriston
- J45A4067Ynystawe, Clydach, Swansea Valley
- J44A48/A48Llansamlet, Swansea (east)
- J43A465Llandarcy, Neath, Heads of the Valleys
- J42A483Earlswood, Briton Ferry
- J41A48Baglan, Port Talbot (west)
- J40A48Port Talbot, Aberavon
- J39A48Cwmavon (west-facing only)
- J38A48Margam, Kenfig
- J37A4229Pyle, Porthcawl, Cornelly
- J36A4061/A4063Sarn, Maesteg, Bridgend (north)
- J35A473Pencoed, Bridgend (east)
- J34A4119Miskin, Llantrisant, Talbot Green
- J33A4232Cardiff West, Capel Llanilltern
- J32A470Coryton, Cardiff (north), Merthyr Tydfil
- J30A4232Cardiff Gate, Pentwyn
- J29A48(M)Castleton — A48(M) for Cardiff (east)
- J28A48Newport (west), Tredegar Park
- J27B4591High Cross, Newport (Rogerstone)
- J26A4051Malpas, Newport (north)
- J25aA4042Newport (Brynglas)
- J25B4596Caerleon, Newport (east)
- J24A48Coldra, Newport (east), Chepstow (A48)
- J23aA4810Magor, Llanwern
- J23M48M48 — old Severn Bridge / Chepstow
- J22M49M49 — Avonmouth link to the M5
- J21M48/A403M48 & Severn crossings, Aust
- J20M5Almondsbury — M5 interchange (Midlands / South West)
- J19M32M32 — Bristol city centre
- J18A46Tormarton, Bath, Stroud
- J17A350Chippenham, Cirencester
- J16A3102Swindon (west), Wootton Bassett
- J15A419Swindon (east), Cirencester, Marlborough
- J14A338Hungerford, Wantage, Great Shefford
- J13A34Chieveley, Newbury — A34 for Oxford / Southampton
- J12A4Theale, Reading (west)
- J11A33Reading (central), Basingstoke (A33)
- J10A329(M)Wokingham, Bracknell, Reading (east)
- J8/9A404(M)/A308(M)Maidenhead, High Wycombe, Marlow
- J7A4Slough (west), Huntercombe
- J6A355Slough (central), Windsor, Eton
- J5A4Langley, Slough (east), Datchet
- J4bM25M25 interchange (London orbital)
- J4A408Heathrow Airport, Uxbridge
- J3A312Hayes, Southall, Heathrow (A312)
- J2A4Brentford, Chiswick (A4)
- J1A4/A406Chiswick — A4 & North Circular (London)
▼ EAST London & the A4 / North Circular
The M4 runs ~189 miles between London and South Wales, crossing the Severn. It meets the M25 (J4b), M32 (J19), M5 (J20), M48 (J21/J23) and M49 (J22). Tap Latest M4 Traffic News and search a junction for live updates.
Also travelling on the M25?
The M4 meets the M25 London orbital motorway at Junction 4b. If your journey also uses the M25, see our sister site M25 Traffic for the latest M25 traffic news and updates in the same easy-to-use format.