Welsh Journals

The original decking of the bridge on which the double railway track was laid consisted of six inch Memel timbers twenty-six feet long, but these rotted and were replaced by iron plates. Renewal of the decking again became necessary in 1925, and one track being removed for the purpose, single-line working with an Electric Train Token was instituted on the other line. After eighteen months the process was reversed and the second half of the decking replaced. The whole task took three years, and at the end of this time, single line working having proved capable of carrying the available traffic, it was maintained until the viaduct was demolished. In the late 1950's about £ 10,000 was spent on repairs, and this, apart from some work done in 1866 and the redecking, would appear to be the only costs in 100 year of use. Painting, of course, was a major task, some fifteen tons of paint being used at intervals of five to seven years, originally performed by contractors but later by railway painters. The permanent way was first laid on twelve inch square (approx.) jarrah timbers with lateral bracing at ten foot intervals, but when relaid in 1928 normal sleepered track on limestone ballast was laid, the decking being protected by bitumen and the ballast confined by a wooden strip each side of the track. A speed limit of 8 m.p.h. was always in force and there were restrictions on the types of engines, among those prohibited were the 42XX, 72XX and others in the "Red" classification. The problem of expansion and contraction in such a long metal structure was met by special bearings in the stone abutments. The expansion of the 1,050 foot length of the main structure was mea- sured as seven-sixteenths of an inch between 4.0 a.m. and 4.0 p.m. on 12th June, whereas the difference in length between 12th February 1861 (32°F) and 27th August 1861 (90°F) was two and three-quarter inches. Prior to its opening on 1st June 1857 the whole viaduct was tested in the presence of Col. Wynne, the Board of Trade Inspector, with six heavy (!) engines on which all available space was filled with pig-iron. This made the total weight 300 tons, which was enough to cover one span on both lines. The resulting deflection varied seven-eighths to one and a quarter inches, the girders return- ing to their normal position when the load was removed. It is interesting to note that when in 1916 similar tests were made to allow 28XX T engines to operate Admiralty coal trains on this route, almost identical readings were obtained. Among the materials used were 2,400 tons of ironwork, 30,000 cubic feet of timber, and 11,000 cubic feet of ashlar masonry, the total cost being £ 62,000. The viaduct was taken out of use in 1964 and demolished in 1965.