Railway Tunnel Portal is a Grade II listed building in the Gwynedd local planning authority area, Wales. First listed on 1 February 1996. House.

Railway Tunnel Portal

WRENN ID
eternal-plaster-fog
Grade
II
Local Planning Authority
Gwynedd
Constituency
Dwyfor Meirionnydd MP: Liz Saville Roberts (PC)
Country
Wales
Date first listed
1 February 1996
Type
House
Address
Railway Tunnel Portal, Llechwedd Slate Mine, Ffestiniog
OS grid reference
SH 696 469
Coordinates
53.0038, -3.9434
Source
Cadw listing

Also on this page: flood risk · radon risk · weather exposure · detailed attributes ↓

Description

The railway tunnel portal, dated 1879, was constructed for the London and North Western Railway (LNWR) at the entrance of the Blaenau Tunnel. It was designed by engineer W. Smith, whose name is displayed on a date plaque above the entrance arch.

The portal features a broad semi-circular arch set within a tapered and pedimented structure. It is made of snecked, rough-dressed stone, with clearly defined voussoirs and a simple arch ring. Above the arch, the pediment includes a central recessed slate date plaque and is topped with a dentillated cornice. On either side of the entrance, there are stepped and angled retaining walls.

This structure is listed for its special interest as a 19th-century railway tunnel portal and for its group value with other listed items at the former Llechwedd railway sidings.

Local climate

Railway Tunnel Portal sits in one of the wettest parts of the UK, with an average of 1,370 mm of rain a year. This makes it wetter than 96% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 93% of listed buildings.

It experiences an average of 49 freeze-thaw cycles a year, more than 90% of listed buildings. Of these, 29 follow at least 1 mm of rain in the preceding 48 hours. Average temperatures at this location have risen by 0.3°C per decade since 1991.

Averages for 1991–2020; temperature trend 1991–2025. Figures describe the wider area (a grid cell of roughly 10 km), not the individual site. Contains modified Copernicus Climate Change Service information 2026.

More on this building

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