Pont Pen y Benglog

Link to Welsh translationLink to French translationPont Pen y Benglog

To appreciate how Thomas Telford’s new road transformed travel in the early 19th century, take a look at the surviving stone arch of the earlier road bridge at this spot. It’s directly below the main arch, and best seen from the rocks to the east of the A5 road. The water rushing under the bridge comes from Llyn Ogwen, the lake to the east.

Near here there’s a “rock step” 100 metres in height. The Ogwen falls tumble down it, to the west of the bridge. The water then flows north on the floor of the Nant Ffrancon valley. Earlier roads climbed steeply here, to leave Nant Ffrancon and continue beside Llyn Ogwen. This caused difficulties for horses drawing carriages and carts.

To improve the reliability and speed of travel between London and Holyhead, Telford ensured that the new road was never steeper than 1 in 20 (meaning a rise of 1 metre over 20 horizontal metres). North of Pont Pen y Benglog, his workmen hacked a cutting through the rock to enable the new road to cross the water at a much higher level than the earlier route.

The road was later widened on the east side – above the remains of the earlier bridge – to provide enough space for motor vehicles and for the pedestrians who linger here to enjoy the fine views. The face of the bridge’s extension was made of slate blocks, copying the form of Telford’s original. You can still see the handiwork of Telford’s stonemasons on the west side.

About the name:

Nant y Benglog is the narrow valley from Capel Curig to Llyn Ogwen. The same name occurs in several parts of Wales with similar landscape, leading some to believe it means “end of the rock” or “above the steep rock”. Here the name Pen y Benglog applies to a distinctive rock (south-west of the bridge) which overlooks the steep rocks and the valley of Nant Ffrancon. However, the more common meaning of penglog is “skull” – an appropriate description of the rock as seen from Nant Ffrancon.

To hear how to pronounce Pont Pen y Benglog, press play: Or, download mp3 (19KB)

With thanks to Prof Hywel Wyn Owen, of the Welsh Place-Name Society

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