Sir Thomas Bouch (IPA: [baʊtʃ]) (25 February 1822 - 30 October 1880) was a railway engineer in Victorian Britain.
He was born in Thursby, Cumbria, England and lived in Edinburgh. He helped develop the caisson and the roll-on/roll-off train ferry. He also built a number of railway bridges, at Belah and Deepdale on an important cross-Pennines route (now defunct, but which survived until the era of Dr Beeching in the 1960s.

Tay Bridge
He designed the first Tay Rail Bridge whilst working for the Edinburgh and Northern Railway. Queen Victoria travelled over it at the official opening in 1878, and she awarded him a knighthood in recognition of his achievement. However, the bridge collapsed on December 28, 1879 when it was hit by strong side winds. A train was travelling over it at a time, and 75 people died, among them Thomas Bouch's son-in-law.
The subsequent public inquiry revealed that the railway company sacrificed safety and durability to save costs. Sloppy working practices such as poor smelting and the re-use of girders dropped into the sea during construction were factors in the bridge's collapse. The inquiry concluded that the bridge was "badly designed, badly built, and badly maintained". All of the high girders section fell during the accident, and analysis of the archives has shown that the design of cast iron columns with integral lugs holding the tie bars was a critical mistake. As the engineer, Thomas Bouch was blamed for its collapse, his assistant Charles Meik, having merely left an impression that he "was aptly named", implying that he had no great influence over the design and construction.