Coryton Interchange

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Coryton Interchange
Cyfnewidfa Coryton
Location Map ( geo)
M4 Approaching J32 e-b - Coppermine - 21848.jpg
Cameraicon.png View gallery (4)
Location
Tongwynlais
County
Glamorgan
Highway Authority
Welsh Government
Junction Type
3-level stacked roundabout
Roads Joined
M4, A470, A4054
Junctions related to the A470
Junctions related to the A4054

Coryton Interchange is junction 32 of the M4.

Home to what is one of the largest roundabouts in the UK. It is just under a mile all the way around and the A470 manages to cross below the circulatory carriageway at the eastern side, but above at the western side!

History

Original junction in existence during the 1970s

A simple grade separated junction was built in the early 1970s when the A470 was dualled towards Merthyr Tydfil which allows the A4054 to pass beneath. A pair of petrol stations on the A470 meant the northbound carriageway was built with a C/D lane to reduce weaving.

At the time it was known that the M4 would be built together with a replacement junction but it was expected that it would be some time into the future as the Llantrisant Radial would be built first. This, along with the A48 Eastern Avenue, would have formed a Cardiff Inner Bypass which would have coped with traffic levels at the time but the Llantrisant Radial was scrapped in 1971 and construction of the M4 around the north of Cardiff was brought forward instead. This meant the junction at Coryton would be replaced earlier than expected. The M4 to the west opened in 1977 and that to the east opened in 1980 giving the original junction a lifespan of around five years.

The replacement junction was improved in the summer of 2014 with the addition of a short link road from the westbound M4 to the A470 north. This enables traffic to avoid several sets of lights around the roundabout.

Routes

Route To Notes

M4

Bridgend/Pen-y-bont

M4

Newport/Casnewydd

A470

Merthyr Tydfil/Merthyr Tudful

A470

Cardiff/Caerdydd

A4054

Tongwynlais

A4054

Whitchurch/Eglwys Newydd
Superstore/Archfarchnad, Forest Farm/Fferm y Fforest



Coryton Interchange
Related Pictures
View gallery (4)
M4 Motorway Intersection near Tongwynlais - Geograph - 609448.jpgM4 Approaching J32 e-b - Coppermine - 21848.jpgCoryton Interchange original layout.pngA470 - M4 Coryton Roundabout - Coppermine - 4101.jpg
Junctions on the M4
Main RouteChiswick • 2 Brentford • 3 Cranford Parkway • 4 Heathrow • 4B Colnbrook • 5 Langley • 6 Tuns Lane • 7 Huntercombe • 8/9 Holyport • 10 Winnersh • 11 Three Mile Cross • 12 Theale • 13 Chieveley • 14 Wickham • 15 Plough Hill • 16 Spittleborough • 17 Stanton St Quinton • 18 Tormarton • 19 Hambrook • 20 Almondsbury • 21 Awkley • 22 Pilning • 23 Rogiet • 23A Magor • 24 Coldra • 25 Caerleon • 25A Grove Park • 26 Malpas • 27 High Cross • 28 Tredegar Park • 29 Castleton • 30 Pentwyn • 31 Junction 31 • 32 Coryton • 33 Cardiff West • 34 Miskin • 35 Pencoed • 36 Sarn • 37 Pyle • 38 Margam • 39 Groes • 40 Taibach • 41 Pentyla • 42 Earlswood • 43 Llandarcy • 44 Lon-Las • 45 Ynysforgan • 46 Llangyfelach • 47 Penllergaer • 48 Hendy • 49 Pont Abraham
Heathrow SpurCherry Lane • 4 Heathrow • 4A Concord
Former RoutesBray • 9A Cox Green • 9B The Thicket // 19 Hambrook • 19A Frenchay // 20 Almondsbury • 21 Aust • 22 Newhouse • 23 Magor // 28  Tredegar Park • 29 St Mellons
Defunct Newport
Bypass Proposal
23 Rogiet • 25 Glan Llyn • 27 Dock Way • 29 Castleton