A48 road

Highnam to Cardiff

The A48 from Highnam to Newport runs adjacent to the River Severn. After running through a series of villages, it crosses the England–Wales border at Chepstow. The section between Higham and Chepstow is still a primary route of some importance for the Forest of Dean. From the M4 Motorway at J15 near Swindon, traffic is directed for Wales if it is over the Severn Bridge weight limit of 44 tonnes. Traffic is directed onto the A419, then onto the A417 after Cirencester, and at Gloucester, onto the A40. This road has some speed cameras, as there have previously been incidents here, and have been erected to prevent them from happening again. During busy periods, such as the Severn Bore, this road may become busy with parked cars near the river's edge. Apart from morning and evening rush hours, the road is generally quite empty and free running, with no heavy traffic reports. The road also runs next to the Forest of Dean. The woods may be viewed from the roadside, as may the hills of the Dean. There is a level crossing in Lydney. Until Chepstow, there is a height limit under the low railway bridges. Tall vehicles are directed to Newport on the A40. For some parts of this route, short distance dual carriageways occur, especially on steep hills. At Chepstow, the road links Gloucestershire with Monmouthshire. The road runs through Chepstow. There is access to the Forest of Dean in Chepstow. At the end of the road in Chepstow (at the roundabout), the Primary Route ends here, and it meets the A466, a road that provides access to the Wye Valley and to the M48 motorway, originally the M4. Access to the M4 is available on this road. The A48 becomes a secondary route here, and continues bypassing Caldicot, Caerwent and Langstone.

The A48 then continues to M4 junction 24, from which point it is also known as the Southern Distributor Road, which is entirely a dual carriageway with two lanes in each direction around the southern end of Newport until M4 junction 28. From junction 28 it remains a dual carriageway until just after the Celtic Way roundabout where it becomes a single carriageway with four lanes past Castleton, and then merges with the junction 29A of the A48(M) motorway at St Mellons, where it again becomes a dual carriageway with two lanes in each direction, where it is known as the Eastern Avenue until the Gabalfa Interchange, where it is known as the Western Avenue and is largely a single carriageway with four lanes until Culverhouse Cross interchange.

Cardiff to Carmarthen

From the Culverhouse Cross interchange on the western boarder of Cardiff the road is mostly a single carriageway with two lanes until Cowbridge, where it becomes the Cowbridge Bypass which is a dual carriageway, until again it becomes a single carriageway with two lanes until Bridgend when it is a dual carriageway again. From Bridgend it becomes a single carriageway, until Port Talbot where it is a dual carriageway, and originally known as the A48(M) (Port Talbot Bypass) until the M4 was extended. The A48 then ends on the western end of the Briton Ferry Bridge at junction 42 of the M4 and starts again at junction 44 where again it is a single carriageway until the end of the M4 at junction 49 where it becomes a dual carriageway and forms part of the main trunk road between Pont Abraham Services to Carmarthen where the A48 ends.