On Friday 24th January 2020, with the promise of a good lunch afterwards, 12 Phoenix gathered for a special “behind the scenes” guided tour of Tower Bridge.
Tower Bridge is a combined bascule and suspension bridge, built between 1886 and 1894 and now 125 years old. The bridge consists of two bridge towers tied together at the upper level by two horizontal walkways. It is – perhaps along with Sydney Harbour Bridge – the most immediately recognisable bridge in the world. But it is more than that; it is actually an engineering masterpiece and a superbly efficient solution to the challenge of enabling both river and road traffic to share the same small section of the Thames.
Our tour started in the North Tower where we paused first to hear the history of the building of the bridge, including viewing one of the diving suits. Two massive piers, containing over 70,000 tons of concrete, were sunk into the riverbed to support the construction. More than 11,000 tons of steel were used in the framework for the towers and walkways, which were then clad in Cornish granite and Portland stone, to protect the underlying steelwork. The bascule pivots and operating machinery are housed in the base of each tower. The original raising mechanism was powered by pressurised water stored in several hydraulic accumulators.
The original brick façade was replaced with the more ornate Victorian Gothic style, which makes the bridge a distinctive landmark, and was intended to harmonise the bridge with the nearby Tower of London.
Then we walked along the two horizontal walkways. Since installing the glass floor sections on the upper walkways, visitor numbers have doubled. As you can see from the photo, Phoenix Masters exercised caution when considering how to traverse this part of the walkway.
On returning to road level, we now moved into the original south control room which reminded us all of a railway signalling box. From here we went down into one of the original engine rooms which still houses an original engine beside the current compact hydraulic system which now drives the opening and closing of the bridge. And it is opened and closed surprisingly often still: the bascules are raised about a thousand times a year, and while river traffic is now much reduced, it still takes priority over road traffic. Today, 24-hour’s notice is required before opening the bridge, and opening times are published in advance on the bridge’s website. There is no charge for vessels to open the bridge.
From here we descended further down past one of the accumulators via a deep spiral staircase which took us to the bascule chamber, the size and shape of which took our breath away. Obviously, we were only able to enter this chamber because the bridge was not due to be opened during our visit.
Finally, we went to the museum which is on the south bank and saw the steam boilers and the original steam engines in motion.
Isobel was delighted to find the original heritage plaque presented by the Institution of Mechanical Engineers with the citation:
“Built to the design of Sir John Wolfe Barry. The whole mechanical construction is unique in the world and acme of steam and hydraulic power of the Victorian era”.
We all enjoyed the tour so much, asking many questions, that we were late arriving for the promised good lunch at the Wine Library. Good red and white wines were swiftly chosen and we soon settled in to reflect on the marvels of Victorian engineering.
In thanking the organisers, John Nugée and Isobel Pollock-Hulf, Past Master Mariner Flavian d’Souza said “My office has been next door for over 30 years but never did I realise so much insight about the magnificent 125 year old Tower Bridge”.