I.K. Brunelbrunel (1806–59), a Brilliant Polymath Who Engineered the Great Western Railway and Numerous Other Works, Including the Design and Construction of Ships
Total Page:16
File Type:pdf, Size:1020Kb
DR JIM SHIPWAY RETROSPECTIVE runel had a striking personality, but he was a civil engineer first Band foremost, with a keen inquiring mind, immense energy, and a supreme ability to lead, inspire and persuade others; he was a brilliant innovator who at times it seemed, had an aversion to following any other man’s lead. What was his real contribution to engineering? Several books have been written about Brunel, his life and times, and in the scope of a single short article assessing his achievements, it is possible to do justice only to a very few of his works. Since he was best known as a railway engineer and a builder of bridges before he became a designer of ships, two of his later railway bridges have been chosen for comment. Brunel’s chief rival as a railway engineer was Robert Stephenson (1803–59), also a great engineer and designer of the Conwy and Menai tubular bridges, but his work lacked the flair displayed by Brunel, and he did not have the same genius for calculation. A note on units: we generally use SI units in Ingenia, but in this historical article we have retained the original Imperial units In the competition organised by the BBC last year for the title ‘The Greatest Briton’, Churchill led the field of ten entries, and the runner- up was Isambard Kingdom Brunel I.K.I.K. BrunelBrunel (1806–59), a brilliant polymath who engineered the Great Western Railway and numerous other works, including the design and construction of ships. It was Some thoughts on his astonishing that this man, little- known to the public and from a profession little understood by it, gained second place in a country- engineering wide competition involving such names as Shakespeare, Nelson, and the Princess of Wales. How did this happen? ingenia 57 RETROSPECTIVE The Great Western Railway Brunel was appointed engineer to the Brunel had a striking personality, a keen GWR in 1833 when he was 27 years old, and it was the first of his railway inquiring mind, immense energy, and a works, extending 118 miles between London and Bristol. It was not supreme ability to lead and inspire others constructed without controversy, since it embodied the startling 7 ft gauge (50% wider than the standard gauge) onwards, but had weakness, in that well (Conwy is still in use today), but and the equally startling two miles long the top flange was vulnerable to the bridges were heavy and Box tunnel, as well as the Maidenhead buckling. Brunel’s skill in design uneconomical in the use of materials, Bridge, which had the longest and manifested itself in flanges with curved mainly due to the closed-in plated flattest semi-elliptical arches ever plates and web branches in several webs. Only five such bridges were constructed in brickwork. The fall of forms, stiffening the flange and the built, and none after 1856. this bridge on completion was girder web together. Meanwhile, the open-web or trussed confidently predicted, but it continues girder, with panels, was gaining ground in use to this day. These features of the in America, where timber suitable for Large-span bridge GWR give the flavour of Brunel’s bridge construction was plentiful and development approach to engineering and of his railway construction was booming. achievements in other fields. In the 1840s the plated-web box These girder bridges were used mainly The development of the girder girder made its appearance on a for spans up to 150 ft, and were bridge in railway work took place in the grand scale with the design of the gradually replaced by all-iron bridges of UK mainly between the years 400 ft span Conwy tubular bridge and the same types. The most popular form 1830–1860, and included lattice the Menai tubular bridge with two main was the Pratt, or N-truss, and later the girders, plate girders, tubular girders spans of 460 ft, both by Robert Warren girder. Early Pratt trusses from and hybrids. These years almost Stephenson. These bridges, in which 1845 onwards had iron ties for diagonal exactly paralleled the career of Brunel, the trains run inside the tube, were members and timber verticals forming and it was natural that he was involved Stephenson’s answer to the then the panels, before the advent of iron. in bridge development, making his own seemingly impossible problem of The all-iron Warren girder followed in the unique contribution. The plate girder bridging gaps of that magnitude. His 1850s, with the construction of the bridge flourished from the 1840s solution was innovative and worked Newark Dyke Bridge in England in 1853. Chepstow Bridge, 1852 In 1852 Brunel was engineer to the South Wales Railway, and had to bridge the river Wye at Chepstow. The Wye had a tidal range of 40 ft, the second highest in the world, and was swift- flowing. The Admiralty insisted on a 300 ft clear width for shipping and 50 ft headroom at high tide. They further The 400 ft spanning Conwy tubular bridge by Robert Stephenson (left) which is still in use today. Bridges such as ingenia Conwy and Menai were excellent engineering achievements but were often uneconomical with materials (Photo: Philip Hawkin) 58 RETROSPECTIVE insisted that the navigation channel be requiring caisson construction for the closed only for the duration of one tide, river piers. This resulted in an Bridge on the River Wye i.e. for 12 hours only. Stephenson had asymmetrical bridge of which one half Brunel’s Chepstow Bridge (above), no such problem at Conwy or Menai. was three 100 ft plate girder spans, and which was built to specific Brunel had a strong artistic streak, the other half was a 300 ft span of quite requirements by the Admiralty, was and most of his work, though functional, different design. The twin tracks were of remarkable for many reasons. It was had much of elegance: for example the the 7 ft gauge, which imposed loading one of the first open-web girder roofs at Paddington Station; Clifton 50% greater than the standard gauge. bridges in Europe, incorporating Suspension Bridge; tunnel portals at The greatest obstacle was the 100 ft by 50 ft open panels crossed Box and elsewhere; and his elliptical maximum of 12 hours allowed for the with chain diagonals as shown in the arch work at Maidenhead, Hanwell possession of the river channel. Brunel photo above. (Photo: Network Rail) viaduct and other masonry bridges. The decided on a separate bridge for each Chepstow Bridge, however, was a plain track, making for smaller pieces to be answer to an engineering problem, and lifted into place. Each bridge was to was ungainly and lacking in charm and be of three panels, each of elegance. Nevertheless it embodied approximately 100 ft, making a engineering of the highest order. gigantic N-truss. The top chord of the The diagram below shows how, with The site is remarkable for the truss was a 9 ft diameter tube built up just 12 hours allowed for occupation contrast between the two sides of the from wrought-iron plating, and the web of the river channel, the main river. On the east side there is a members were chain links chosen for Chepstow Bridge member was erected limestone cliff 120 ft high, and on the lightness and easy handling. The west there is low-lying alluvial material vertical members of the truss were Final 300 ft 3rd Final position 9 ft 3rd position 1st position 2nd position ingenia 59 RETROSPECTIVE The construction of The Royal Albert Bridge at Saltash (left). The two main spans, each of 455 ft, were lifted into place one at a time; both met at the centre pier which was founded on rock 16 ft below the bed of the 70 ft deep river. The parabolic tubular arch is matched exactly by the sag of the chains, the two being vertically braced apart and strengthened with cross-bracing A–frames, and joined the tube to the designed, would be an improvement. The 300 ft spans at Chepstow lasted plate girders supporting the deck. The Thus the Warren girder with its 110 years until 1962, when they were heaviest part of each bridge was triangular open web arrived at Newark replaced owing to the increase in therefore the 300 ft long tube, which Dyke in 1853 and slightly later at loading from heavier traffic. Thus weighed 161 tons and spanned the Crumlin. In the USA, advances in passed into history these remarkable entire navigation channel. Brunel’s plan design, mainly in timber, had been iron spans, the first in Europe to have was to launch the tube on barges made in the 1840s and later by Pratt, open-web N-truss panels. There were across the channel, then lift it in stages Howe, Whipple and others who no others in iron outside America until by jacks to the required clearance in developed the concept of panels in J.H. Latham’s railway bridge at the course of a single day. The framed structures for modest spans. Allahabad, India, in 1859–65, which scheme worked brilliantly, and the first But Brunel led the field in Europe. had spans of 210 ft, a long way short of the two bridges was completed in At Chepstow his gigantic, open, 100 ft of Chepstow. three months between April and July panels, 50 ft high, crossed by chain 1852. The second bridge was diagonals, were an impressive completed the following year. advance, and the N-truss became The Royal Albert Bridge, But the real genius of the design lay established as a cheap and easily Saltash, 1859 in its structural form, in the fact that it constructed structural form.