|Location Map ( geo)|
|1.5 km SE of Margam|
|single motorway on-slip|
Groes Interchange, located about 2.5 miles south-east of Port Talbot town centre, is junction 39 of the M4 motorway. As far as motorway traffic is concerned, the interchange amounts to a single slip road providing access from the A48 to the westbound carriageway of the M4. All other movements between the motorway and the A48 are dealt with at the Margam Interchange (junction 38) which lies two thirds of a mile further south-eastwards.
The roundabout at this site, as first built in the 1960s, originally formed the south-eastern terminus of the A48(M) (Port Talbot Bypass) and its junction with the A48. When the motorway was extended eastwards a decade later (the whole route becoming part of the M4), it followed a route close to the north-eastern, landward side of the A48. The selection of this alignment entailed the complete destruction of the village of Groes: its 22 homes and school were demolished and its landmark octagonal chapel was dismantled and rebuilt on a new site half a mile to the north-west, so that the name "Groes" now survives only as that of a motorway junction.
A quarter of a mile or so of the westbound carriageway of the former A48(M) between the roundabout and the present M4 was retained as a west-facing slip road; as noted above, other traffic movements between the motorway and the A48 are handled at the nearby junction 38.
|Abertawe / Swansea|
|Caerdydd / Cardiff||For westbound M4|