Tower Bridge 29th January 2011

Hard to believe that it has been a month since our last post.  We have done so many things since then.  Every weekend we find another place to see, to learn about, to photograph and to enjoy.  It is a wonderful way to start the weekend where Rod and I discuss what we will do for the day.  The weekend of 29th & 30th January we headed off to Tower Bridge.  This is the one most of us call London Bridge which in fact is wrong.  The idea for another bridge was started in 1876 because the London Bridge was not coping with the amount of traffic that was crossing the river.  A competition was held in 1884 and finally the design was selected out of 50 designs submitted.

It took 8 years, 5 major contractors and the relentless labour of 432 construction workers to build Tower Bridge.

Two massive piers were sunk into the river bed to support the construction and over 11,000 tons of steel provided the framework for the Towers and Walkways. This framework was clad in Cornish granite and Portland stone to protect the underlying steelwork and to give the Bridge a more pleasing appearance. 

When it was built, Tower Bridge was the largest and most sophisticated bascule bridge ever completed ("bascule" comes from the French for "see-saw"). These bascules were operated by hydraulics, using steam to power the enormous pumping engines. The energy created was stored in six massive accumulators, as soon as power was required to lift the Bridge, it was always readily available. The accumulators fed the driving engines, which drove the bascules up and down. Despite the complexity of the system, the bascules only took about a minute to raise to their maximum angle of 86 degrees.

Today, the bascules are still operated by hydraulic power, but since 1976 they have been driven by oil and electricity rather than steam. The original pumping engines, accumulators and boilers are now exhibits within the Tower Bridge Exhibition.  (All that was for those people who are technically minded).  A fascinating exhibition on the history, building of and how it still works today is in the upper walkways which are accesssible by lifts.  We also went down to the engine room to see the engines.  It is at present undergoing renovation so the bascules are not working until March.  It is still an impressive sight.  We had to follow the blue line to get to the engine room at the east side of the river.  They must have had problems previously with the tourists understanding so have now made it very clear.