As the subject for this week’s materials blog from your favourite repair specialist we have chosen metal: primarily steel, with an honourable mention for cast iron, which means we can reflect on some of the most striking structures ever to be created by the construction sector; as well as some of the most spectacular failures.
During my engineering degree, the lecturers always seemed keen to offer cautionary tales and two which stood out were the Tacoma Narrows suspension bridge in America and the original Tay Bridge in Scotland. Both fell victim to poor engineering and high winds, though with quite different consequences.
Film footage of the US – unserviceable rather than United States – effort is almost comical as the deck twists back and forth while the wind blows; and one brave soul staggers drunkenly down the centre line of the deck to rescue a dog left trapped in a car. All that is left in the end is the steel cables and the two main towers.
Back in 1879, however, after weeks of warnings about weaknesses and speed restrictions on the rail line across it, a packed train vanished into the icy waters of the Tay with tragic loss of life. The enquiry revealed that the cast iron columns and beams – produced in a foundry on the shore – were not only cracked and pitted, but had been ‘patched up’ with a mixture of iron filings and wax.
Problems similar to those of the Tacoma Narrows incident re-emerged in 2000 when the Millennium Bridge across the Thames near the Tate Modern quickly became known as the “wobbly bridge”. Rather than high winds this time, it was pedestrians walking in step which drove the natural harmonics of the structure, requiring substantial extra bracing before it could be re-opened.
Most bridges, however, provide trouble-free and long term service, as has been the case with the UK’s first metal bridge at Ironbridge Gorge near Coalbrookdale, or the ‘Bridge over the Bosphorus’ at Istanbul which links Europe to Asia.
The strength of steel, as we observed, helped designers ‘reach for the sky’ with the Empire State Building in New York being the world’s tallest structure when opened in 1931. It has been surpassed many times since, with the title currently being held by Burj Khalifa in Dubai. However, people continue to flock to the viewing deck above New York’s Fifth Avenue, as well as the slightly shorter vantage points this side of the Atlantic – in Paris and on Blackpool’s Golden Mile.
My personal nomination, however, for the most significant steel structure, is the gasometer which stands opposite the press box at The Oval cricket ground in South London. In fact as a lifetime fan of the world’s slowest sport, I was reminded of it recently when two of our Finishers were called to repair some of the desks within the commentary box at Lords, which got damaged when the excited commentators, watching a game, were banging their microphones and other objects on the edges – very high tech, but lacking the gritty realism of the perch where Brian Johnson and his colleagues on the Test Match Special Team made endless observations regarding the gasometer’s level of fullness as they munched slices of chocolate cake during the endless rain breaks.
Meanwhile, our teams of Finishers continue to make good dents, scratches and other damage done to steel members, aluminium cladding panels and all types of architectural metalwork on buildings across the country.