(Photo 10 © RCAHMS (Aerial Photography Collection))
The coal and iron pits around Airdrie spawned three railways as servants, stretching from Kirkintilloch to Linlithgow. These came together in 1848 to form the Monkland Railways. In July 1853 the company obtained Parliamentary powers to connect the former Slamannan line at Blackston Junction to Bathgate and Armadale.
The route's most striking structure was a viaduct featuring 12 main spans, each of 47 feet, over the River Avon's wide valley near Westfield. In addition, pairs of smaller arches were accommodated into the abutments. Standing 60 feet high, the single-tracker plots its course for a little over 220 yards. At its south-eastern end is an approach embankment of about 130 yards.
Except for the brick arches, the viaduct is built in stone, the first of which was laid on 11th August 1854. An inaugural coal train traversed the branch on 11th June 1855 although passenger services did not receive the Board of Trade's approval for another 13 months. The route over the viaduct closed on 28th December 1964.
British Railways Board (Residuary) look after the structure, number BKN/10 on its inventory. Despite receiving a Grade B listing in November 1974, parts of it are in poor condition, particularly on the north-east elevation. All but two of the main spans are strengthened with tie bars - three per arch - passing both through the spandrels and beneath the barrel. These are held in place with long iron plates keyed into the masonry. Above one of the arches, a sapling has taken root causing considerable damage to the adjacent voussoirs. Many patch repairs have been carried out in brick, owing to widespread loss of the stone faces.
The viaduct's slender piers broaden slightly at their feet and all are topped with two-stage bedstones. Buttresses are incorporated between the main and smaller arches, forming generous refuges at deck level, but there are no refuges above any of the piers.
Despite its failings, Westfield Viaduct is a fine and attractive addition to the local landscape.