On Saturday morning, June 30, 1894, crowds of Londoners rushed to the Tower of London. It seemed that not a single person wanted to miss a grand event: the most technically perfect bridge in the world, Tower Bridge, was commissioned.
While Londoners were waiting for the action, a carriage drove out of Buckingham Palace. After driving down Pall Mall, Strand and Fleet Street, the Princess and the Prince of Wales arrived at the bridge to the music of the Royal Artillery Band. Then the carriage drove back and forth across the bridge several times, and when the audience was properly warmed up, the Prince of Wales got out of the carriage and began the solemn ceremony. Speaking on behalf of his mother, Queen Victoria, he walked over to the silver bowl set on a pedestal and turned it. The bowl played the role of a handle for controlling the hydraulic equipment of the bridge, so at the moment of its rotation the huge wings of the bridge rose silently by 86 degrees, causing an explosion of applause. Looking at how quickly and silently the bridge was raised, the public applauded the technologies, naively believing that they had reached the peak of perfection.
However, in some ways they were right.
It was the dawn of the era of mechanics and steam. As if heralding the triumph of those technologies, the members of the royal family, after the opening of Tower Bridge, did not get into the carriage again, but went to Westminster on the small steamer Pump.
About the world's first traffic jams
The technical excellence of the bridge was not the only reason that gathered a crowd of thousands that Saturday morning. Tower Bridge was long-awaited for Londoners. The oldest bridge in the city, London, was built of stone as early as the 12th century, in 1750 he was accompanied by another stone bridge - Westminster. Over the next hundred years, eight more stone bridges were built in the world capital, but all of them were erected west of London, upstream. London Bridge was the only one in its busy area, so it was probably here that people first learned what traffic jams were - then still human and carriage. Sometimes the crossing to the other side of the river took at least an hour. Moreover, congestion, as in our time, usually occurred due to road accidents, in the form of, for example, the sudden death of a horse.
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The city authorities made efforts to make life easier for citizens. In 1871, the Tower Tunnel was opened, passing under the Thames. A ferry crossing was also organized here. But the problem was not solved: a new bridge had to be built.
Fifty projects
In February 1876, the London authorities announced an open competition for the design of the new bridge. According to the requirements, the bridge must be high enough to allow massive merchant ships to pass under it, as well as to ensure the continuous movement of people and carts. About 50 interesting projects were sent to the competition!
Most of the contestants offered options for high bridges with fixed spans. But they had two common drawbacks: the distance above the water surface at high tide was insufficient for the passage of ships with high masts, and the ascent to the bridge was too steep for the horses pulling carts. One of the architects proposed a bridge project in which people and carts were raised to a high bridge using hydraulic lifts, another - a bridge with ring parts and sliding decks. However, Sir Horace Jones, the city's chief architect, was recognized as the most realistic project. Despite all the advantages of the project, the decision on its choice was delayed, and then Jones, in collaboration with the famous engineer John Wolfe Barry, developed another innovative bridge, eliminating all the shortcomings of the first in the new project. Barry, in particular, suggested to Jones to make the upper walkways, which were not in the original project.
After three weeks of heated discussion, the Jones-Barry project was approved. The enormous sum of £ 585,000 was allocated for the creation of the grandiose structure. The developers of the bridge became very rich overnight - their fee was £ 30,000. In 1886, construction began, but in May 1887, even before the foundation was laid, Jones suddenly died, and the entire responsibility fell on the engineer Barry. The latter invited the talented architect George Stevenson as his assistant, thanks to whom the bridge underwent a number of stylistic changes. Stevenson was a fan of Victorian Gothic architecture and expressed his passion for the bridge design. He also decided to show off the steel trusses of the bridge: a new structural material - steel - was in fashion at that time, and it was in the spirit of the times.
Tower Mechanisms
By the time Tower Bridge was built, drawbridges were no longer surprising. But the remarkable thing about the Tower Bridge was that its lifting and lowering were entrusted with sophisticated techniques. And never before has hydraulics been used on such a scale in bridges. In St. Petersburg, for example, at that time the labor of workers was usually used to draw bridges, which was eventually replaced by the work of water turbines powered by the city water supply.
Tower Bridge was powered by steam engines, which rotated pumps that created high water pressure in the accumulators in the system. From them the hydraulic motors were "fed", which, when the valves were opened, began to rotate the crankshafts. The latter transmitted torque to the gears, which in turn rotated the toothed sectors, which ensured the raising and lowering of the bridge wings. Looking at how massive the lifting wings were, you might think that the gears were carrying enormous loads. But this is not the case: the wings were equipped with heavy counterweights that aided the hydraulic motors.
At the end of the 19th century, shipping on the Thames flourished, so Tower Bridge was raised around the clock. But despite this, the public practically did not use the pedestrian bridges of the upper level. The wings were turning so quickly that it was faster and more convenient to wait at the bottom than to climb up, even though the elevators intended for this, also powered by the hydraulic system. Therefore, for most of the past century, the upper pedestrian bridges were closed.
An interesting fact: if at the beginning of its history the Tower Bridge was considered incredibly advanced, then in the post-war period it became, on the contrary, conservative. Londoners seemed to cherish the steam-mechanical soul of the structure, not wanting to modernize it with the attributes of the age of electricity. So, the gas lamps of the Tower Bridge were replaced with electric lamps only in 1966! For comparison, the Liteiny Bridge in St. Petersburg began to be illuminated with electric arc lamps in 1879.
Under the onslaught of progress, the steam mechanism for driving the bridge wings did not give up for a long time. Until 1972, stokers worked on Tower Bridge. But then it was still replaced by an electric drive system. The old water hydraulic system was replaced with a new oil one. These two measures have significantly reduced the cost and labor intensity of bridge maintenance. True, in our time he rarely gets divorced: usually no more than ten times a week.
Despite these changes, Tower Bridge continues to delight people who are not indifferent to mechanics. The old mechanisms here still stand in their rightful place, and today everyone can go into the machine rooms and admire the technique of the Victorian era.
Tower Bridge cars
Renowned engineer John Wolfe Barry oversaw the development of the Lift-Deploy Bridge mechanism. When his colleague, the architect Horace Jones, died, he became responsible for the appearance of the building.
Scheme. Tower Bridge was powered by steam engines installed under the southern access road. They operated water pumps, which supplied high pressure water to the bridge hydraulic system. Since during operation it was required to instantly supply high power to the bridge mechanisms, water was pumped into six accumulators. Two of them were on the southern bank of the river, and a couple more - in each of the bridge's bulls. The lifting wings were equipped with counterweights weighing 406 tons each (the total weight of one wing was 1220 tons).
1. Steam engine pump
Two pumps supplied water to the hydraulic system at a pressure of 5.2 MPa. They were driven by steam engines, for which steam at a pressure of 0.45-0.48 MPa was supplied from four large Lancashire boilers.
2. Drive motor
To drive the lifting wings of the bridge, eight hydraulic motors were installed, which began to work after turning the system valves. The latter were controlled from two control rooms installed on each bull of the bridge.
The first drawbridge system of the Tower Bridge was hydraulic, based on two steam engines with a total capacity of 360 hp. from. It was written by engineer Hamilton Owen Rendel, who worked for Sir Armstrong (one of five contractors) and Newcastle upon Tyne.
The system was quite complex - steam engines, which were fired with coal, pumped pressure into the accumulators, pumping water from the Thames there. The working pressure was 50 bar. When the accumulators were opened, the water transferred energy to the hydraulic motors, and they already rotated the crankshafts connected to the gears of the sliding sections. At the same time, the load on the adjustable mechanism is not so great, the rising wings of the central span are equipped with counterweights, and the total breeding time even in the 19th century took no more than a minute.
Another fact is often overlooked - in 1942, a third engine was installed, which was supposed to ensure the operation of the bridge even if part of the system was damaged.
In 1974, the mechanism was replaced, now oil is used in the hydraulic system instead of water, and its compact and safe electric motors are pumped. From the original adjustable mechanism, only the final gears are used, which are installed directly on the axes of the span. But the original mechanisms have been preserved and some of them are the main exhibit of the Tower Bridge Museum. And in 2000, a failed attempt was made to computerize the bridge; the computer control worked normally only in 2005 after replacing a number of components.
Bridge incidents
Throughout its history, Tower Bridge has become the object of many rather curious and interesting cases. Fortunately, most of them were with happy outcomes:
In December 1952, a double-decker passenger bus made a cinematic jump from one half of the bridge to the other as it began the process of opening the span. This happened due to a mistake by the manager, and the bus driver, when he realized what was happening, decided to turn on the gas. In the end, no one was hurt, and the driver was awarded a small bonus.
On April 5, 1968, Royal Air Force pilot Alan Pollock decided to hold an air show when he learned that the command was not planning any events for the 50th anniversary of the troops. He took off without permission in his fighter jet and flew through the bridge. The pilot was arrested and, then, the court fired him from the Air Force on medical grounds.
In the summer of 1973, clerk Paul Martin flew twice through the bridge in a small single-engine plane in protest. The bridge worked out well, but it crashed two hours later.
In May 1997, Bill Clinton's motorcade was split in two, causing security forces to panic. It turned out that the person in charge of the bridge acted lawfully to let the barge pass, and they tried to warn the US Embassy, but no one answered the calls.
On August 19, 1999, an honorary citizen of the City of London decided to drive two sheep across the bridge. In this way, he implemented one of the old English laws to draw public attention to too vague and outdated legal norms.
On the morning of October 31, 2003, David Creek climbed onto the bridge in a Spider-Man suit and spent 6 days there in protest. All this time, the bridge was blocked by the police, which caused huge traffic jams and criticism from the townspeople.
On May 11, 2009, a really terrible incident happened - one of the elevators in the bridge towers fell along with the passengers. Fortunately, the height turned out to be small and everyone survived.