In this blog Colin Divall describes how sometimes the railway plans can help crack open age-old puzzles.
Timber was often used for bridges on the early railways, especially when they were cheaply built like the Southampton and Dorchester; Dorset’s first main line. At Wimborne, the River Stour was crossed by a timber viaduct that was striking enough to feature in the Illustrated London News‘s report on the line’s opening in June 1847.
But these structures often didn’t last long. Timber quickly rotted, especially in the days before effective treatments, or caught fire when embers dropped from steam engines. In August 1854, the Southern Times newspaper reported that:
‘On reaching the viaduct between Poole and Wimborne, the bridge was discovered to be on fire…’.
Additionally, timber bridges soon became too weak for trains’ increasing weight and speed.
So how long did the Stour viaduct last? Until recently we knew that it had gone by about 1876, thanks to a plan of Wimborne station held in the National Railway Museum. Many people have suggested that it would’ve been replaced by 1863, when a second track was laid between Wimborne and Wool. But we had no firm evidence. Indeed, the inspector’s report on the second track implied that the original viaduct was possibly still in use.
Thanks to the conserved plans we can now narrow the window considerably. The Dorset Central Railway’s plan of November 1855 for the line to Blandford shows the original viaduct (we can tell from the shape of the embankment):
While from 1864 we have a plan showing the northern end of the new structure:
Therefore, it seems likely that the viaduct was indeed replaced as part of the line’s more general upgrade, although perhaps not until just after the inspector made his report. Digging in the archives might yet tell us more!
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This is part five of an eight part series of blogs on the work we are doing to conserve the railway plans.
Part 1: Getting the Records Back on Track
Part 2: The Importance of the Railway Plans and Sections