An impressive iron-truss viaduct over the steep wooded valley of the Bilston Burn in Midlothian, the Bilston Glen Viaduct is unique as the only A-listed structure of its type in Scotland. The structure is 137m (450 feet) in length, comprising a central span of 100m (330 feet) and two side spans each of 18.3m (60 feet) emerging from sandstone abutments. Opened in 1892, it carried the single-track Edinburgh, Loanhead and Roslin Railway at the remarkable height of 42.7m (140 feet) above the valley floor. The railway lost its passenger service in 1933 and the viaduct was abandoned with the loss of mineral traffic on the line following the closure of Moat Colliery in Roslin in 1969.
For many years, access to the viaduct was blocked and it was threatened with demolition. However, it re-opened in 1999 following a £1.4 million restoration project, to carry a recreational path, part of the Midlothian Strategic Footpath and Cycle Network.
Work included repairing and repainting the metal structure, restoring the stone abutments, the installation of a new deck and parapets, and the replacement of four massive roller bearings which allow movement of the viaduct with changes in ambient temperature. Two of the old bearings remain on-site with an interpretation panel, while the other pair are displayed the ICE Scotland Museum at Heriot-Watt University.
Ownership of the viaduct passed to the Edinburgh Greenbelt Trust and the restoration work was supported by a group of funders including the British Railways Board, the European Union, the Heritage Lottery Fund, Historic Scotland, Lothian and Edinburgh Enterprise, Midlothian Council, Railway Heritage Trust and Scottish National Heritage.
This is the second viaduct at this location - the first was a six-span structure which was the work of Thomas Bouch (1822-80) and had opened 1873. Perhaps because of the risk of undermining by nearby coal mines or perhaps as part of the re-examination of all of Bouch's bridges following the Tay Bridge Disaster of 1879, the viaduct was rebuilt and reduced to a three-span structure with more substantial supporting piers.
