The A470 is the north-south highway running the length of Wales. Mostly a quiet rural drive, it's suddenly transformed between Cardiff and Merthyr Tydfil, becoming a major and unique expressway route.

Think of the busiest roads in Wales and you will inevitably think of the M4 and the A55. You might also bring to mind the A465 Heads of the Valleys Road, and the A449 down the Usk valley. Often overlooked, though, is the twenty or so miles between Cardiff and Merthyr, a section of the A470 that carries as much traffic as many lengths of the Welsh M4 and considerably more - two or three times more, in fact - than the A55.

This section is, by any meaningful measure, an urban motorway. The length from the M4 to the A472 at Abercynon was built during the late 1960s and early 1970s and is a fast-paced, grade-separated route through a continuously built-up steep-sided valley. It comes complete with full hard shoulders and split-level running along hillsides.

If you enjoy ingenious 1960s highways threaded through town centres and difficult terrain, there's really nothing in the UK to match it; it's like a version of the M8 through Glasgow with better scenery. The ambition of the project was considerable; it originally came with an interchange at Coryton, but when the M4 arrived, that was replaced with Coryton Interchange - a three-level stacked roundabout interchange, yes, but one notable for having what is believed to be the UK's largest roundabout. The size of the roundabout, and the number of parallel lanes it carries, is scarcely believable until you've driven around it.

The "Cardiff-Merthyr Road" built in the late 1960s ran from the M4 to Abercynon, where the towns and villages spreading north from Cardiff along the valley of the Taff begin to thin out. It was extended in the 80s to reach the A4060 eastern bypass of Merthyr at Pentrebach. It was then extended further in the mid 1990s, passing around the west side of the town, to bypass the A470 through to a point north of Cefn Coed. That new length pushed the fast and very scenic dual carriageway further north, but it's not quite the same road - no longer at all urban, and with a series of flat roundabouts instead of those motorway-style junctions.

The chances that the expressway A470 will ever extend further north are very slim; north of Merthyr Tydfil right through to its northern extremity at Llandudno, the rest of the A470 is a much quieter route. But it will eventually connect to another modern expressway at Cefn Coed, where the final phase of the A465 dualling project will give this almost-motorway a northern terminus on Wales' new east-west route between Swansea and Raglan.

You're not looking at the whole A470

This page is about the parts of the A470 that are designated a motorway or that have motorway characteristics. Other sections of this road will not be featured here and will not count towards the length of the road as shown below.

Start
Merthyr Tydfil
End
Cardiff
Connects to
Length
21 miles
Open Junctions Section
Nov 1971 Tongwynglais - Nantgarw
Dec 1972 Nantgarw - Glyntaff
Nov 1973 Glyntaff - Abercynon
Nov 1985 Abercynon - Pentrebach
Nov 1996 Pentrebach - Swansea Road
Jul 1997 Swansea Road-Cefn Coed

Exit list

Junction   Northbound               Southbound  
Castell-Nedd
Neath A465
Aberhonddu
Brecon A470
Y Fenni
Abergavenny A465







A465
NORTH
A470







A465
LanesLanesLanesLanes LanesLanesLanesLanes
1 mile, 2 lanes 1 mile, 2 lanes
Gelli-deg
Merthyr Tudful
Canol y dref
Merthyr Tydfil
Town centre
A4102
A4102 Merthyr Tudful
Canol y dref
Merthyr Tydfil
Town centre
A4102
Gelli-deg
LanesLanesLanesLanes LanesLanesLanesLanes
1.2 miles, 2 lanes 1.2 miles, 2 lanes
Rhyd-y-car
A4102
A4102 Rhyd-y-car
A4102
LanesLanesLanesLanes LanesLanesLanesLanes
1.6 miles, 2 lanes 1.6 miles, 2 lanes
Pentrebach
A4060
Y Fenni
Abergavenny (A465)
A4060
(A465)
Pentrebach
A4060
Y Fenni
Abergavenny (A465)
LanesLanesLanesLanes LanesLanesLanesLanes
5 miles, 2 lanes 5 miles, 2 lanes
Signs Signs
0.6 miles, 2 lanes 0.6 miles, 2 lanes
Aberpennar
Mountain Ash
Aberdâr
Aberdare
A4059
Ystrad Mynach A472
Aberfan (A4054)
A4059 A4054
A472
A4054
Ystrad Mynach A472
Aberfan (A4054)
Aberdâr
Aberdare
A4059
LanesLanesLanesLanes SignsSigns LanesLanesLanesLanes SignsSigns
0.6 miles, 2 lanes  
Services Abercynon
LanesLanesLanesLanes
0.5 miles, 2 lanes  
Abercynon
B4275
B4275


A4054

A4054
LanesLanesLanesLanes
3 miles, 2 lanes 3.4 miles, 2 lanes






A4223






(A4054)
Pontypridd A4223
Cwm Rhondda
Rhondda Valleys
(A4058)
Ynys-y-bwl (B4273)
Llantrisant
(A473)
LanesLanesLanesLanes
   
Pontypridd
Cwm Rhondda
Rhondda Valleys
A4058
Ynys-y-bwl (B4273)
A4058




LanesLanesLanesLanes
0.6 miles, 2 lanes  
Llantrisant
(A473)
B4595

A4054
A4054


LanesLanesLanesLanes
1.9 miles, 2 lanes 3.2 miles, 2 lanes
Rhydfelen
Rhydyfelin
A4054
A4054
A473
A4054
Yst Ddiw Trefforest
Treforest Ind Est
A4054
LanesLanesLanesLanes LanesLanesLanesLanes
1.6 miles, 2 lanes 1.6 miles, 2 lanes
Yst Ddiw Trefforest
Treforest Ind Est
A4054
Caerffili
Caerphilly
A468
(A4054) A468 Caerffili
Caerphilly
A468
Ffynnon Taf
Taff's Well
A4054
LanesLanesLanesLanes LanesLanesLanesLanes
1.7 miles, 2 lanes 1.7 miles, 2 lanes
Ffynnon Taf
Taff's Well A4054
Radyr B4262
A4054
B4262




A4054
Tongwynlais
A4054
Radyr B4262
LanesLanesLanesLanes LanesLanesLanesLanesLanes
1.1 miles, 2 lanes 1.1 miles, 3 lanes
(M4 J32) M4

A4054

A470
SOUTH
A4054

M4



Casnewydd
Newport
Pen-y-bont
Bridgend
M4 Link
LanesLanesLanesLanes SignsSigns LanesLanesLanesLanesLanes SignsSigns
Routes

Picture credits