A48(M) (Morriston Bypass)

This article is about the Morriston bypass, now M4 junctions 44 to 46.
For spur towards Cardiff from M4 junction 29, see A48(M).
For the Port Talbot bypass, now M4 junctions 39 to 41, see A48(M) (Port Talbot Bypass).
For the unbuilt Llantrisant Radial in Cardiff, see A48(M) (Llantrisant Radial).

For detailed information about this topic, see Pathetic Motorways

Confirmation of the opening date and number of the M4 Morriston Bypass

Route Confirmation just east of Llangyfelach Interchange

The towns of Morriston and Llansamlet, situated to the north of Swansea, were bypassed in 1972, the road comprising the current 3.9 mile section of M4 from J44 Lon-las to J46 Llangyfelach.

The M4 near Ynysforgan

As the road going through town was the A48 the bypass was originally planned as the A48, then, when the decision was made to build it as a motorway, as A48(M). It is shown on some maps as the A48(M) during the construction phase, which was consistent with the nearby A48(M) (Port Talbot Bypass). In fact, while it was initially planned with the number A48(M), by the time of construction, the road was built and opened as M4. It is thought that the change was made some time in 1970, about two years before opening. As a statement of intent, the motorway carried a Route Confirmation Sign which included London 191 on it. This survived for many years, but had been removed by the time the M4 was completed to London in the mid 1990s.

History of the Scheme

The A48(M) number for the Morriston Bypass made it onto the OS One Inch sheet from 1972

Information in this article has been taken from the inauguration document for the M4 Morriston Bypass. Early proposals for a northern bypass for the Swansea area were published in 1936, and were subsequently revisited in 1954 in conjunction with the nearby A48 Lon Las to Earlswood to Baglan scheme including the first Briton Ferry Bridge. Responsibility for roads in Wales was taken over by the Secretary of State for Wales in 1965 and the road formally entered the road into the roads programme, being planned as a full motorway as part of a western extension of the M4 from Newport. It is described as the East of Llansamlet - Llangyfelach Special Roads scheme in The Gazette notice of 14 February 1969

Contracts

An advanced contract was awarded to RM Douglas in October 1969 for £385,000 to form an embankment on poor ground between the River Tawe and Clydach Road and to blast a cutting through rock near Morriston School. In April 1970, a second advanced contract was also awarded to RM Douglas for £108,000 to demolish some redundant side road bridges and to modify some side road routes to accommodate the motorway.

The main contract was awarded to Messrs. John Laing Construction Ltd for £3,576,000 and work commenced on 28th August 1970.

Opening

In 1975, Hansard stated that the opening was August 1972. Glamorgan Archives has a document listed for the inauguration ceremony on 16 September 1972. No notice of opening has been seen in The Gazette at the time. However, a Land Compensation Act notice, published much later, on 16 July 1981 in the Port Talbot Guardian describes the road as M4 Morriston Bypass with a date of opening of 24 August 1972. This suggests that the motorway was opened to traffic before the official inauguration on 16 September 1972.

Features of the bypass

The eastbound on-slip at Lon-Las, turning off the right hand side of the roundabout carriageway

The scheme included 14 bridges. Notable among these are those at Junction 44 and the viaduct at Junction 45, two rail bridges and three footbridges. The western terminus had no bridges at the time, with the motorway ending at an at-grade roundabout. The Inauguration Brochure records that the Welsh Office hoped that the westward continuation of the M4 (towards Pont Abraham) would be complete within four years. In fact, it took five years to complete, opening in 1977 along with much of the rest of the western extension of the M4 from Newport.

The construction project also included an eastern continuation of the motorway which was opened as A48 and made the road continuous with the previously completed road to Earlswood and Briton Ferry Bridge. The Lon-Las interchange has a curious slip road which leaves the roundabout in the centre rather than from the outside, and then drops down to the motorway, passing under the other side of the roundabout.

Videos

M4 motorway in 1972

A drive through of the M4 Morriston Bypass shortly after opening in 1972.

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