Railway Viaduct, River Irvine, Laigh Milton Mill

This is a stone railway viaduct built between 1809 and 1811 by William Jessop, and restored in 1995-96 by Barr Limited. The bridge, 5.8 metres wide, spans the River Irvine and has four rounded arches each with a 12.2-metre span. The design includes rounded cutwaters with half-column buttresses rising through deck bands to parapet level. The construction is of coursed rubble masonry with rusticated free-stone to the arch voussoirs, cutwaters and buttresses. The abutments curve outwards on the river banks, with railway tracks approaching through cuttings. The bridge deck is of crushed stone, and the parapets have been renewed with new metal railings.

Originally named Milton Bridge, it was built as part of the Kilmarnock and Troon plateway, which opened in 1812 as the first public railway in Scotland and ceased operation in 1846. It is the oldest surviving bridge in Scotland built for railway use. The railway operated with a travelling steam engine hauling coal as early as 1816, though the engine was not initially successful enough to replace horse-drawn traction. The contractor for the original construction was likely John Simpson (associated with Thomas Telford), who was paid approximately £4,000 for the work, representing a medium to low-cost build. The restoration was funded by seven different organizations and involved temporarily damming the river, using steel frameworks to support the arches, stabilizing the piers, strengthening the spandrels, and creating a new deck. Defective masonry was replaced and the structure was repointed with lime mortar. The viaduct was formerly known simply as a disused railway viaduct.