During my time modelling railways, I can’t recall building a layout that didn’t feature a bridge of some type. I have always found the aspect of a train in an elevated situation such as a bridge an appealing modelling subject. In last month’s article, we focussed primarily on bridges that are used on land, now we focus on those that cross the water.
Swing bridges
Usually built as either a truss or beam, active underline railway swing bridges rotating on a vertical axis have become rare on main lines. The installation at Banavie, crossing the Caledonian Canal on the Fort WilliamMallaig extension carries a single track, but at Selby, the swing bridge, spanning the River Ouse conveys double track. This was a section of the East Coast main line until 1983, but the opening of a diversionary route to York resulted in the nearby station only handling Hull-Doncaster workings.
Crossing Oulton Broad, a swing bridge once carrying a double track route between Beccles and Lowestoft has been reduced to single track working. In Mid-Wales, Barmouth viaduct, Grade two listed, has carried the Cambrian Coast line 840m (2,750ft) across the Mawddach estuary since 1867. In 1900, the iron ‘over-draw’ or draw bridge span was replaced by two steel spans that include a swing bridge.
Built in 1901 by Alan Findlay & Co for the West Highland Railway, the Banavie hogback, open-work, movable span pivots on the south bank under the control of Banavie signalling centre. This controls all movements extending to Helensburgh, Oban and Mallaig. The location of the centre was selected because of itsaction.
