Most South African’s know that there are two statues in London honouring South African icons Field Marshall Jan Smuts and Nelson Mandela, both in Westminster’s Parliament Square.
But very few realise that there is a third statue honouring a South African engineer, James Henry Greathead.
James Henry Greathead was one of the 3 giants of engineering in Victorian England, alongside Sir Joseph Bazalgette and Marc Brunel, and if it wasn’t for his ingenuity, London’s underground, the first underground rail network in the world, might have had to wait a while longer to become a reality
James Greathead was born in Grahamstown in the Cape Colony in August 1844, and was educated at St. Andrew’s College.
In 1855 the Greathead family travelled back to England for 4 years during which time Greathead completed his schooling at Westbourne Collegiate School in London, graduating in 1863. He returned briefly to South Africa before finally moving to London in 1864 to serve a three-year apprenticeship under the civil engineer Peter W. Barlow, where he became acquainted with the shield system of tunnelling.
London was expanding rapidly at this time, and due to the congestion within central London, it had become imperative to find ways to ease the congestion within the city centre and to facilitate transportation into the outer suburbs.
The obvious choice was the use of trains as a transport system, but more importantly the two parts of London on opposite sides of the Thames had to be connected, and tunnels were the obvious solution.
Marc Brunel’s (father of the great Isambard Kingdom Brunel) Thames Tunnel, has already completed the world’s first underwater tunnel, in 1843, but when the tender for the Tower Subway was issued in 1863, James Greathead, aged only 24, was the only contractor prepared to tender.
In 1869, Greathead and Barlow began work on the designs for the Tower Subway, only the second tunnel to be driven under the river Thames in central London. Barlow was the engineer for the tunnel and Greathead was in charge of the actual drive.
By this time, a number of engineers were already engaged in tackling the challenges of new methods of tunnel engineering. Greathead’s genius lay in his ability to look at existing technologies and to adapt them to new situations. The tunnelling shield for driving the Tower Subway, designed by Greathead, was a radical improvement on earlier designs patented by Barlow.
Greathead radically re-imagined the tunnelling shields of the day, dramatically improving both efficiency and safety.
The so-called Barlow-Greathead shield consisted of an iron cylinder 2.21m in diameter, fitted with screw jacks which enabled it to be jacked forward. In use, the shield was inched forward as the working face was excavated, while behind it a permanent tunnel lining of cast iron segments was fitted into place, itself an important innovation.
Greathead patented many of his improvements including the use of compressed air and forward propulsion by hydraulic jacks, both of which are now standard features of tunnel construction.
Greathead’s new design, also included a chamber in which the tunnelers could jack the shield into the newly excavated space using the completed portion of the tunnel casing behind it.
The tunnel was slightly larger than the shield, which allowed for the use of Greathead’s other innovation — the injection of a liquified cement grouting into the gap, allowing the tunnel to fuse with the clay surrounding it, meaning that Greathead was also the inventor of shot concrete and spray cement, used so extensively in construction today.
On average, the tunnellers managed to fix 6 rings per day, meaning that the tunnel progressed at an impressive 3 metres per day. Essentially, Greathead’s innovation was the evolution of the modern Tunnel Boring Machine.
Although both of the first two tunnels under the Thames were economic failures, they were also substantial engineering achievements, with this dramatic difference — Brunel’s Thames tunnel project ran for some 19 years, including all the disasters and interruptions, whereas excavation of Greathead’s Tower Subway took 14 weeks for 300 m of horizontal tunnel, plus two vertical 20m shafts at either end, the entire system being approximately 410 m long. As a bold engineering experiment, Greathead’s expeditious construction of the Tower Subway was indeed a triumph, and a foretaste of things to come.
A third tunnelling shield was later patented by Greathead that introduced hydraulic pressure nozzles at the tunnel face to blast away soft earth. The nozzle itself was also another Greathead patent invention.
When Greathead had originally tendered for the contract, he undertook to complete the tunnel in under a year, at a cost of £10,000. He achieved both goals
During the Second World War, Londoners used the “Tube” as air raid shelters, which undoubtedly saved thousands of lives. The tunnel remained watertight, even surviving a near miss in 1940 during the ‘Blitz’ without yielding.
When a belated decision was finally made in 1994, to honour Greathead’s contribution to the underground, the site chosen was of considerable symbolic importance.
An imposing equestrian statue of the Duke of Wellington, celebrating his historic victory at Waterloo, graces the intersection of Threadneedle Street and Cornhill, projecting into Bank Junction like the prow of a ship, and directly behind the statue, in front of the Royal Exchange, is city’s memorial to Londoners who died in the two World Wars.
If the heart of London is anywhere, this is it, and locating James Henry Greathead’s statue here seems entirely appropriate.