The section which incorporated the Yeovil branch is the part adjacent to the River Parrett, which was grossly prone to flooding at Langport West station, down the branch and thus not rebuilt. The thoughts of the gangers at Taunton was the whole 1900 main line over The Levels had indeed still been built about 5 feet too low, not only for physical flooding but also to install effective drainage under the tracks and over the winter water table (it's quite variable here between winter and summer). The news pictures from some years ago of an HST amid extensive floodwaters was on exactly this stretch, it is actually the worst bit. Train timer Cecil J Allen once commented, on reviewing his various speed logs over time, how often there was a permanent way check on this section. You can see what was raised at, for example, Athelney level crossing, which is a substantial hump in the road.
Up and over at Athelney ...
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There's nothing to prevent a major railway being built across such wetlands, as practice elsewhere clearly shows - otherwise there would be no railways in much of Florida.
In passing the M5 motorway, which closely parallels Brunel's original line from Weston to Taunton over this ground, built in the 1970s, also had major subsequent problems with subsidence, and had to be substantially rebuilt after about 10 years. Its substructure was originally done with a large number of trainloads of fly ash from power stations, Aberthaw in South Wales and others, which were hauled in by double-headed Class 37 for a considerable period during construction, to special sidings near Highbridge. I think they used different material in the rebuilding. I wonder if Mr Brunel was laughing ...
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