The A48(M) motorway in Wales links Cardiff with Newport.

At St Mellons, it runs continuously into the dual-carriageway A48, which also has (albeit narrow) hard shoulders.

[1] The M4 was extended west from junction 29 in 1980.

[2] The 6-mile (9.7 km) Port Talbot bypass which opened in 1966,[1] was numbered A48(M) before its incorporation into the westward extension of the M4 in the 1970s.

[citation needed] Some maps show the Morriston bypass section of the M4 as also having been originally numbered A48(M), although whether this number was ever used on the ground has been questioned.