 When the Marquis of Lothian built his waggonway southwards from the Dalhousie Mains terminal of the E&DR, he had to cross the South Esk river; he did so by a viaduct consisting of 24 spans of timber with three pointed arches in cast iron.It was designed by John Williamson in 1830 and opened on 21 January 1832.It was superseded when the North British Railway were extending southwards; they replaced it with a 23 span masonry viaduct with brick arch rings, completed in 1847 and still in situ.