Pen-y-Clip Tunnels

The A55 trunk road passes through Pen-y-Clip headland, between Penmaenmawr and Llanfairfechan, by means of three tunnels and a viaduct. The two short tunnels and the viaduct, now normally used by eastbound traffic, were built in the mid-1930s. The much longer tunnel, normally used by westbound traffic, was built in the early 1990s as part of the dualling of the A55 from Chester to Bangor (later extended to Holyhead).

There is also a parallel 19th-century railway tunnel and viaduct.

The 1935 Northern Tunnels and Viaduct

The 1935 viaduct and one of the tunnels at the higher level above the railway viaduct

The road was opened on 5 October 1935 by L. Hore-Belisha, Minister of Transport. It comprised tunnels of 180 and 100 feet either side of a seven arch viaduct. Each arch was 80 feet and maximum height was 95 feet. The piers of the viaduct had to be sunk 31 feet into the ground to counteract movement of the mountain side. Contractor was M.A. Boswell of Wolverhampton, cost £200,000. Originally for two-way traffic, it became the eastbound carriageway after the South tunnel was opened in 1993.

The 1993 Southern Tunnel

The 1993 tunnel

The tunnel route was eventually chosen from three options. One of the rejected options involved an overland route for the westbound carriageway, with the eastbound following the old route through the 1935 tunnels. The third option was a new viaduct rising out of the sea for eastbound traffic, with westbound traffic using the 1935 tunnels.

The 930 m tunnel was opened in October 1993. It was designed by consultants Travers Morgan and Howard Humphreys and Partners. Contractor was Laing Civil Engineering. It was part of a £51 million scheme. It was described as Britain's longest road rock tunnel. Tunnelling was more difficult than what the borehole results had shown. The outer thirds had open joints infilled with clay, and only the centre section was through rock. It became the westbound carriageway, with the 1935 North Tunnels and viaduct becoming the eastbound carriageway.

The pedestrian and cycle route

In 2009 two foot/cycle bridges were completed, spanning the westbound carriageway in front of each portal of the 1993 tunnel, to provide a safe route for pedestrians and cyclists, clear of the carriageways, between Penmaenmawr and Llanfairfechan. This route consists largely of Telford's original road which was the A55 before the 1935 tunnels were built.

The footbridges have been criticised on aesthetic grounds and because they are not suitable for horses.