The headland of Penmaenmawr had been a transport obstacle during the eighteenth century and carriages previously used the sands at low tide. A turnpike trust was established in 1769 and John Sylvester engineered a road circa 1772; that was followed by a railway built by Stephenson in 1848. The Penyclip Road Tunnels were built on a realignment of the A55 Chester to Bangor road (nprn 403728) between 1930 and 1936. The alignment includes two tunnels and a stone-arched viaduct and now carries only eastbound traffic; since 1993 westbound traffic has used a new tunnel (nprn 91426).

Sources include: David Gwyn & Merfyn Williams (1996) `A Guide to the Industrial Archaeology of North West Wales?. Association for Industrial Archaeology

RCAHMW, 14 November 2011.