Llangyfelach Interchange

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Llangyfelach Interchange
Cyfnewidfa Llangyfelach
Location Map ( geo)
M4, Junction 46 - Geograph - 3688680.jpg
Cameraicon.png View gallery (1)
Location
Llangyfelach
County
Glamorgan
Highway Authority
Welsh Government
Junction Type
dumbbell
Roads Joined
M4, A48, B4489

The Llangyfelach Interchange, junction 46 of the M4, was built over a period of about 30 years between 1972 and the mid 2000s. Prior to 1972 the junction was a simple T-junction, with the B4489 descending a rather steep hill to the A48, which was the main east-west trunk road of its day.

The junction was selected as the western terminus of the M4 Morriston Bypass (known during development stages as the A48(M)) and to accommodate the new motorway, a new roundabout was built. The roundabout is essentially the main roundabout that exists today, except that both carriageways of the M4 tied into the roundabout at the point where the westbound off-slip does now, the westbound off-slip being a remnant of the westbound carriageway.

In 1977, the M4 was extended west to bypass Pontarddulais. To achieve this, a new eastbound slip road was built from the roundabout, bridging over the line of the new motorway, and rejoining the eastbound carriageway. This enabled the original eastbound carriageway and the westbound carriageway to be re-modelled to form a limited-access junction with the extended motorway. West-facing slips were not provided at this stage as this movement was accommodated at the Penllergaer Interchange to the west.

North-west of the interchange lies the former Felindre Steelworks site, accessed from a T-junction west of the Llangyfelach interchange. When this site was redeveloped it was deemed necessary to provide west-facing slips at Llangyfelach as well as a direct link to the development site. A second bridge was built to the east of the 1977 bridge, and at a slightly higher level in order to provide adequate forward visibility onto the main roundabout. The two bridges were linked at the northern end by a half roundabout arrangement which turns the two bridges into a "longabout". The link to the development site was built here, the eastbound on-slip was modified to suit the new arrangement, and a new eastbound off-slip built to link from the M4 main line. The westbound on-slip was built from the original roundabout to the main carriageway.

Routes

Route To Notes

M4

Llanelli, Carmarthen / Caerfyrddin

M4

Neath / Castell-nedd, Cardiff / Caerdydd Formerly A48(M)

A48

Swansea / Abertawe, Penllergaer, Penllergaer Business Park / Parc Busnes Penllergaer,
Bryntywod, Afon Tin Plate

A48

Morriston Crematorium / Amlosgfa Treforys, D.V.L.A, Morriston / Treforys, Hospital

B4489

Felindre, Park and Share / Parcio a Rhannu

B4489

Llangyfelach



Llangyfelach Interchange
Related Pictures
View gallery (1)
M4, Junction 46 - Geograph - 3688680.jpg
Other nearby junctions
SwanseaEarlswood Interchange • Lon-Las Interchange • Penllergaer Interchange • Ynysforgan Interchange
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
Junctions on the A48
Highnam Roundabout • Highbeech Roundabout • Parkwall Roundabout • Coldra • Beatty Road Roundabout • Hartridge Farm Road Roundabout • Balfe Road Roundabout • Queensway Meadows Roundabout • Nash Road Roundabout • Church Street Roundabout • Maesglas East • Maesglas West • Ebbw Bridge Roundabout • Tredegar Park • St Mellons • Culverhouse Cross • Sycamore Cross • Waterton Cross • Margam • Groes • Earlswood • Lon-Las • Llangyfelach • Penllergaer • Pont Abraham • Cross Hands • Pensarn