M4 motorway
- The M4 motorway is also a motorway in the Republic of Ireland, on the route from Dublin to Sligo. See N4 road and Roads in Ireland.
The M4 motorway is a motorway in the UK, which goes west from London past Bristol to Wales
Westbound
- The M4 starts six miles west of central London where the A4 merges into the M4 on a raised flyover. (The A4 continues in its own right below the flyover.)
- Junction 1 (restricted access): A205 South Circular, A406 North Circular, A315 Chiswick, A4.
- Junction 2: A4 Staines, Hounslow.
- Heston services.
- Junction 3: A312 Heathrow Airport Terminal 4 and cargo, Hayes, Harrow, Feltham.
- Junction 4: M4 spur Heathrow Airport terminals 1, 2 & 3, A408 Uxbridge. Access via spur to Junction 4a and A4 east and west.
- Junction 4b: M25 Heathrow Airport Terminal 4 and cargo, Gatwick Airport, Watford, Oxford.
- Junction 5: A4 Colnbrook, Langley, B470 Dachet.
- Junction 6: A355 Slough central, A332 Windsor.
- Junction 7: A4 Slough west.
- Junction 8/9: A404(M) High Wycombe, Henley, A308M Maidenhead.
- Junction 10: A329(M) Reading east, Wokingham, Bracknell.
- Junction 11: A33 Basingstoke, Reading central and south.
- Reading services.
- Junction 12: A4 Theale, Reading west.
- Junction 13: A34 Newbury, Oxford, Chieveley services.
- Junction 14: A338 Hungerford, Wantage.
- Membury services.
- Junction 15: A346 Marlborough, A419 Swindon, Gloucester.
- Junction 16: A3102 Swindon west, Wootton Bassett, Calne.
- Junction 17: A350 Chippenham, A429 Cirencester.
- Leigh Delamere services.
- Junction 18: A46 Bath, Stroud.
- Junction 19: M32 Bristol.
- Junction 20: M5 The south west, Bristol west, The midlands, Gloucester.
- Junction 21: M48 Chepstow This is the old M4
- Junction 22: M49 Avonmouth.
- Second Severn Crossing (bridge).
- Junction 23: No exit
- Junction 23a: Magor services. B4245 Magor, Caldicot.
- Junction 24: A455/A48 Newport east, A449 Monmouth.
- Junction 25: B4596 Caerleon.
- Junction 25a: A4042 Newport, Cwmbran.
- Junction 26: A4051 Newport.
- Junction 27: B4591 High Cross.
- Junction 28: A48 Newport, A467 Risca, Brynmawr.
- Junction 29: A48(M) Cardiff east and south.
- Junction 30: A4232 Cardiff east.
- There is no Junction 31
- Junction 32: A470 Cardiff north, Merthyr Tydfil.
- Junction 33: Cardiff West services. A4232 Cardiff west, Barry, Penarth, airport.
- Junction 34: A4119 Llantrisant, Rhondda.
- Junction 35: A473 Bridgend, Pen-coed.
- Junction 36: Sarn Park services. A4061 Bridgend, A4063 Maesteg.
- Junction 37: A4229 Porthcawl, Pyle.
- Junction 38: A48 Port Talbot.
- There is no Junction 39
- Junction 40: A4107 Port Talbot.
- Junction 41: A48 Briton Ferry.
- Junction 42: A483 Swansea and ferry.
- Junction 43: A465 Neath, Merthyr Tydfil.
- Junction 44: A48 Swansea east.
- Junction 45: A4067 Swansea, Pontardawe.
- Junction 46: B4489 Swansea north.
- Junction 47: Swansea West services. A483 Swansea west.
- Junction 48: A4138 Pontarddulais, Llanelli.
- Junction 49: End of motorway. Pont Abraham services. A48 Carmarthen, Pontarddulais, A483 Ammanford.
Eastbound
- Start of the motorway. Pont Abraham services. A48 Carmarthen, Pontarddulais, A483 Ammanford.
- Junction 48: A4138 Pontarddulais, Llanelli.
- Junction 47: Swansea West services. A483 Swansea west.
- Junction 46: B4489 Swansea north.
- Junction 45: A4067 Swansea, Pontardawe.
- Junction 44: A48 Swansea east.
- Junction 43: A465 Neath, Merthyr Tydfil.
- Junction 42: A483 Swansea and ferry, A48 Briton Ferry.
- Junction 41: A48 Port Talbot.
- Junction 40: A4107 Port Talbot.
- There is no Junction 39
- Junction 38: A48 Port Talbot.
- Junction 37: A4229 Porthcawl, Pyle.
- Junction 36: Sarn Park services. A4061 Bridgend, A4063 Maesteg.
- Junction 35: A473 Pen-coed.
- Junction 34: A4119 Llantrisant, Rhondda.
- Junction 33: Cardiff West services. A4232 Cardiff west, Barry, Penarth, airport.
- Junction 32: A470 Cardiff, Merthyr Tydfil.
- There is no Junction 31
- Junction 30: A4232 Cardiff east.
- Junction 29: No exit.
- Junction 28: A48 Newport, A467 Risca, Brynmawr.
- Junction 27: B4591 High Cross.
- Junction 26: A4051 Newport, Cwmbran, Caerleon.
- Junction 25a: No exit
- Junction 25: No exit
- Junction 24: M50 The Midlands, A48/A455 Newport, A449 Monmouth.
- Junction 23a: Magor services. B4245 Magor, Caldicot.
- Junction 23: M48 Chepstow This is the old M4
- Second Severn Crossing (bridge).
- Junction 22: M49 Avonmouth, The south west.
- Junction 21: No exit
- Junction 20: M5 The south west, Bristol west, The midlands, Gloucester.
- Junction 19: M32 Bristol.
- Junction 18: A46 Bath, Stroud.
- Leigh Delamere services.
- Junction 17: A350 Chippenham, A429 Cirencester.
- Junction 16: A3102 Swindon west, Wootton Bassett, Calne.
- Junction 15: A346 Marlborough, A419 Swindon east. A420 Oxford.
- Membury services.
- Junction 14: A338 Hungerford, Wantage.
- Unnumbered junction reserved for military use
- Junction 13: A34 Newbury, Oxford, Chieveley services.
- Junction 12: A4 Theale, Reading west.
- Reading services.
- Junction 11: A33 Basingstoke, Reading central and south.
- Junction 10: A329(M) Reading east, Wokingham, Bracknell.
- Junction 8/9: A404(M) High Wycombe, Henley, A308(M) Maidenhead.
- Junction 7: A4 Slough west.
- Junction 6: A355 Slough central, A332 Windsor.
- Junction 5: A4 Colnbrook, Langley, B470 Eton, Dachet.
- Junction 4b: M25 Heathrow Airport Terminal 4 and cargo, Gatwick Airport, Watford, Oxford.
- Junction 4: M4 spur to Heathrow Airport terminals 1, 2 & 3, A408 Uxbridge, Hayes. Access via spur to Junction 4a and A4 east and west.
- Junction 3: A312 to Heathrow Airport Terminal 4 and cargo, Hayes, Harrow, Hounslow.
- Heston services.
- Junction 2 (restricted access): A205 South Circular, A406 North Circular, A315 Chiswick, A4.
- Junction 1: No exit
- The M4 ends six miles west of central London where it becomes the A4.