1st March 2019 • Tower Bridge Blog
How does Tower Bridge work? Part 3.
This month we’re going to look at how Tower Bridge works today and why it changed from steam to electrical power in 1976.
When Tower Bridge was first built, London was an extremely busy trading port. However, as trading ships became larger, fewer and fewer vessels made the journey to the Upper Pool of London (west of Tower Bridge) and a much larger port was built further down the River Thames and closer to the sea.
By the late 1960s, Tower Bridge only opened a few hundred times a year (down from over 6,000 in the first year) and steam was no longer an efficient way to open the Bridge. So, in 1970 it was decided that something needed to be done to make the bridge more efficient and economical to lift, reducing its emissions and bringing it into line with new rules around clean air in London.
In 1974 the installation of a new electro-hydraulic system began, which used electric pumps to create oil-hydraulic energy to turn the cogs used to open the bascules. These new engines were installed while the steam system was still in operation, so the Bridge could still open for passing river vessel.
In 1976, work was completed, the Bridge became fully electro-hydraulic powered and the old system was disconnected - it has remained the same ever since.
Interested in getting up close to the original Engines? Tower Bridge’s Steam Engines can be seen in the atmospheric Engine Rooms located at the south side of Tower Bridge. This area is included in the standard price of admissions.