The Tower Bridge is a combined drawbridge and suspension bridge that crosses the River Thames and is an iconic symbol of London. It consists of two bridge towers tied together at the upper level by two horizontal walkways. The walkways were designed so public could cross the bridge when it was raised but was later closed down due to lack of use. The drawbridge opens for river traffic at 24 hours’ notice around 1,000 times a year. You can check the advanced bridge lift time here.
Each of the drawbridge pivots, and its operating machinery are housed in the base of each tower. The bridge deck is freely accessible to both vehicles and pedestrians, whereas the bridge’s twin towers walkways is accessible by lifts. The Victorian engine rooms on the ground floor together forms part of the Tower Bridge Exhibition.
Glass walkways were introduced in 2014 and measures 11 meters long and 1.8 meters wide along the 61 meters walkway and consist of six separate panels weighing more than ½ ton each. Apart from experiencing stunning panoramic views surrounding the Thames from 42m above the river, visitors can view vessels sailing under the bridge and pedestrians crossing on the road below. On specific days, you can even catch the rising and lowering of the drawbridge right beneath you. The glass is five layers thick and can hold the weight of an elephant.
The original drawbridge lifting mechanism were powered by pressurised water back then, has now been replaced by modern electro-hydraulic drive system. Some of the original hydraulic machinery has been retained, although no longer in use, is open to the public and can be viewed in the engine room south side of the bridge.