Thames Tunnel

Those interested in the tunnel might find the Brunel Museum at Rotherhithe worth a visit

I think that some of the wording of "A worm's-eye view" article is not quite as clear as it might be.

Whilst it is quite true to say that “the shield was first used during the excavation of the Thames Tunnel” the shields that were used in the tunnel were both of rectangular form rather than being circular. The vertical height of a rectangular excavation had the advantage that it was less than the diameter of a circular bore so lessening the risk of cutting through the layer of clay above the tunnel. It had been thought that this would keep the river out but this proved to be a vain hope. 

Marc Brunel had no suitable power source for the earth-boring augers featured in some of his proposed designs for circular shields and their cast-iron lining panels. So, in 1825, the first rectangular shield began its slow advance under the river. Work stopped in 1828 and resumed in 1839 when the original shield was dismantled and replaced by a new one of improved design, of necessity also rectangular in shape. The work of this shield was completed late in 1841 though the tunnel was not opened until 1843. 

I think that the first tunnel in the UK to be constructed with the use of Mr. Greathead’s circular shield would have been the Tower Subway which opened in 1870. this tunnel was dug by hand and was lined with cast-iron panels. As mentioned in the article, mechanically – powered digging machines first appeared in the late 1800s and were in successful use under London from the early 1900s.

Anyone really interested in the epic saga of Marc’s Thames Tunnel might find the Brunel Museum at Rotherhithe worth a visit. It is sited directly above the southern end of the tunnel.

David Wadley, Harefield

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