|Location Map ( geo)|
The interchange was opened in two sections. M4 junctions 28 to 29 and the A48(M) spur (including the bridge carrying the eastbound A48(M) over the future M4) was opened in October 1977. On that day, work officially started on the construction of M4 junctions 29 to 32, which was officially opened in July 1980.
Running parallel and adjacent to the westbound carriageway of the A48(M) is a section of abandoned carriageway. There was a school of thought which said that this was the original eastbound carriageway of the A48(M) running directly onto the M4, however there is no evidence to support this. Later research on the SABRE forums suggests that this section of carriageway was built as a temporary diversion for the wstbound carriageway during maintenance work.
|Cardiff (N & W)/Caerdydd (G a Gn), Bridgend/Pen-y-bont|
|Cardiff (E & S)/Caerdydd (Dn a D)|
|London/Llundain, Bristol/Bryste, Newport (S)/Casnewydd (D)||Unbuilt route south of Newport|