Groundbreaking: The story of the M4's Brynglas bottleneck

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The Brynglas Tunnels at Newport have been, for many years, one of the great points of congestion on the M4 motorway. At rush hour, morning, noon and night, there is invariably a queue and waits of twenty or thirty minutes are the norm. Very few people who travel the M4 on a regular basis have managed to avoid the traffic snarl up at the tunnels.

Yet, in their way, the twin tunnels are as much an engineering marvel as the nearby Transporter Bridge and their official opening on 5 May 1967 marked a significant moment in the history of British road travel.

The two tunnels carry the M4 under Brynglas Hill and are 1,200 feet (366 metres) in length. They were the first tunnels on any British motorway and are still the only 'bored tunnels' on the road system.

Brynglas Tunnels and Newport M4 Bypass construction. Copyright Peter Elliott / St Mary's Film Society

Sitting adjacent to the Usk Bridge, the tunnels were planned as early as 1959 when the design and development of the British motorway routes were first planned. Work began on the tunnels on 10 September 1962 and was finished four years later.

Construction of the tunnels was not without problems. Several houses on Brynglas Road had to be demolished due to structural weakness in the rock below, which had become apparent during the construction work. The houses were duly knocked down and the families re-housed with compensation.

The real problems, however, came after the work was finished and the roadway was in use. The twin bore tunnels were, of course, a wonder, but they were out of date almost as soon as they were finished.

Brynglas Tunnels in 1966, looking west. Copyright Peter Elliott / St Mary's Film Society.

The enormous growth of road traffic on the new motorway meant that the M4 between the present Junction 24 and 28 had to be widened to three lanes, each way. There was no problem with that but when the motorway came to Brynglas it had to be reduced to two lanes again – with the result that, at peak times, there was an inevitable bottleneck.

A serious fire in the westbound tunnel on 26 July 2011 forced the temporary closure of both bores. A lorry had caught fire and although the vehicle was removed – with the assistance of a driver passing through the tunnel – it showed the vulnerability of the Brynglas Tunnels should disaster strike.

Work was finished on extending the width of the motorway in 1982 and although the tunnels have been under regular discussion, nothing has really been done since then. There have been proposals and plans but the cost has always been considered too great. However, a Welsh Assembly consultation document was issued in March 2012 and, it is hoped that changes might actually occur soon.

The Brynglas Tunnels in 1966. Copyright Peter Elliott / St Mary's Film Society.


The Brynglas Tunnels remain an engineering marvel and it's amazing to think that it was nearly fifty years ago that they were first opened.

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