The New Zealand Railways Magazine, Volume 12, Issue 9 (December 1, 1937.)
Avalanche Protection Works
Avalanche Protection Works.
Between the precipitous slope of Penmaenmawr Mountain, in Carnarvonshire, and the sea, engineers of the L. M. & S. Railway are busy at present on the task of rebuilding and strengthening the roof of a railway tunnel constructed specifically as a protection against avalanches. This tunnel extends in two sections, for 145 yards on the east side, and for 50 yards on the west side, of the main Penmaenmawr tunnel (itself 250 yards long) by which the main-line to Bangor and Holyhead passes through the seaward extremity of the Penmaenmawr Mountain. The avalanche tunnel has a roof of steel girders and timber, with a layer of earth above, extending from the sea-wall on one side of the railway, to the retaining-wall which supports the face of the mountain on the other. The tunnel roof is set at an angle of thirty degrees from the horizontal, so as to deflect an avalanche over the railway into the sea.