The iron railway bridge that stands today across the mouth of the River South Esk to the north of the Montrose Basin was designed by W R Galbraith and built by William Arrol & Company Ltd for the North British Railway Company at a cost of £17,000. This viaduct was built to replace another viaduct near the site which had originally been designed by Thomas Bouch and built by Gilkes Wilson & Company. The original 30 span viaduct had only been completed for a few months when, on 28 December 1879, Bouch’s Tay Bridge collapsed. Following this disaster, the South Esk Viaduct was rigorously inspected and found to be unsafe. The decision was made to replace it but, due commercial demands, it was to be kept open for goods trains until a replacement bridge could be built. Improvements were made to strengthen the original bridge, and after testing to ensure it could cope with freight traffic, it was opened in March 1881.
William Arrol & Company Ltd were awarded the contract to build the replacement bridge to Galbraith’s design in May 1881. The replacement bridge was a single-track railway of wrought iron lattice girder, a design dating back to the 1830s. The Bridge was 1430 feet (440 metres) long consisting of 14 spans supported on pairs of cross-braced cylindrical piers made from riveted iron plates filled with concrete. The upper edge of each span has a bowstring curve giving the bridge a scalloped effect.
It was during the sinking of the foundations for the piers that William Arrol first adapted the use of floating pontoons as working platforms.
Dismantling of the original viaduct began in December 1882 but due to safety fears the new viaduct was not to be opened to passenger traffic until the original was completely removed. Eventually, in March 1883, having passed numerous strength and safety tests, the new South Esk Viaduct was opened to passenger trains.