Around the late BC and onwards, explorers were fascinated to discover new parts of the world. Due to our lack of knowledge back then, and our lack of geographical skills and knowing, we were unaware of the technological advancements that places other than Europe were making. Although the UK and France, for example, had booming empires and economies, tribes and towns in other continents were making unknown breakthroughs.
It is said that Alexander the Great was the first explorer to set foot in central Asia and northern India in 330 BC.
Soon after, in 250 BC Greco-Bactrian, a Greek Explorer, ruled central Asia and parts of Punjabi areas; the Greeks began to intertwine with Asia. In 30 BC till 640 AD the Romans began to trade with Asia.
There has been a relationship between the European Mediterranean since before recorded history, so it’s not exactly clear who discovered Asia or even Africa, but since 300 BC, Europeans sparked an interest in the enchanting and mysterious continents.
The reason to why this is relevant is because the first traces of Primitive Suspension Bridges were discovered in Africa and Asia.
Primitive Suspension Bridges
The Pygmy Tribe in Africa built a primitive Suspension Bridge made entirely of vines; the explorer Sir Francis Younghusband revealed another primitive SB in New Guinea, known as a V-Section Suspension Bridge:
‘When crossing, one has to step on one rope and hold two ropes on each side’ (1896)
‘weaving and twisting twigs from birch trees’ (1896)
A third example of a primitive Suspension Bridge is the Kazura Bridge in Iya Village, Japan. These bridges are modifications of ‘Rope Crossing/ Dancing’ found in mountainous areas.
Suspension Bridges were unknown to Western Civilisation until the Medieval period.
First Early Modern Suspension Bridge
The first early modern Suspension Bridge was in 1810, during the industrial revolution, called Jacob Creek Bridge in Pennsylvania. The designer and engineer, James Finley, born in Ireland, and moved to Pennsylvania.
Features of his invention included:
- Installed anchorages and towers
- Separation of the main cables from the deck
- Wrought iron chains
- Level deck
The bridge does not exist anymore, due to its collapse in 1820. It was due to a combination of heavy snow and many loads of six-horse wagon teams. It was later replaced in 1935 by the countries first Cast-Iron bridge called Dunlap’s Creek Bridge.
Introduction to Europe/ French-Style Modern Suspension Bridges
The French Government employed Louis Henri Navier (1785-1836), a scholar to study into Suspension Bridges. He attempted to construct Pont des Invalides in Paris (1823), however he abandoned the construction. It would have been the second largest Suspension Bridge in the world, however sliding occurred in the structure and the construction was never resumed.
In 1822, Marc and Camille Sequin brothers, began to research and experiment with wire and Suspension Bridges; they concluded that:
‘was successful in extending span length and supporting heavy loads’
They designed le Pont de Saint-Vallier (1824) but was however not built due to the fact that it had stiffness problems and they were too complicated to fix and make adjustments.
Nonetheless, Marc Sequin and Guillaume-Henri Dufour (1787-1875) built the first full-scale and successful Suspension Bridge called le Pont de Saint-Antoine in Geneva, Switzerland. Even though it was built in Switzerland, it is the first real French-Style Modern Suspension Bridge built for use in Europe.
The two previous Bridges do not count as they were not actually in function and were experimental.
Two years later appeared the Menai Straits Bridge (1826) of which interlinks Wales and the island of Anglesey; it is regarded as well as the Pont de Saint-Antoine as one of the earliest Suspension Bridges. At the time of its construction it was the longest-span Suspension Bridge in the world. Again, engineers were starting to introduce ideas such as limestone and marble, as well as using linseed oil to prevent rusting. The engineer involved in this construction was called Thomas Telford.
However, back in 1838, the iron cables were replaced with steel elements to increase the stiffness and the bridge stopped suffering from resonance and swaying.
North American Engineering Development
Between 1820 and 1840, there was a dry period of successful Suspension Bridges. in the USA, compared to Great Britain. In 1830, a young studious boy from Pennsylvania called Charles Ellet Jr (1810-1862) took an interest into Suspension Bridges so much that he studied in Paris until 1832. Afterwards he returned to the US and entered a Bridge Design competition, however did not win. Nonetheless, he went on to build, at 22 years old, the first wire cable French-Style Suspension Bridge called the Schuylkill River Bridge in 1841-1842 in Fairmont, Pennsylvania.
Then in 1847, an engineer John Roebling went on to design and build the Niagara River Railway Carriage Bridge, with a span of 244 m, over the Niagara River crossing over to Canada; it was the worlds first successful Suspension Bridge to carry normal rail traffic. However, it did not stay successful for long as it collapsed due to being too weak and having low stiffness – change was needed. The bridge was repaired by using materials with a higher Young’s Modulus (Stiffness), and engineers created hybrid suspension/stay system. Suspension Bridge design increased greatly and advancements were made, and bigger and better Bridges were becoming more apparent. However up until the 1940′s, due to the failure of the Tacoma Narrows Bridge, engineers and architects put their Suspension Bridge dreams on hold and changed the direction of Suspension Bridges once again.
However Charles Ellet did get it right with John Roebling, in the year 1849, the Wheeling Suspension Bridge was open to the public and vehicles. It was the largest Suspension Bridge in the world until 1851, and remarkably is still intact today. Since then, there have been alterations to the materials to make it stiffer, wide, to add a pathway for pedestrians and stay cables were added. However it still exists to this very day.
Birth of the Modern Suspension Bridge
In 1867, John Roebling started the construction of the Brooklyn Bridge in New York and wasn’t completed until 1883. At the time the bridge was completed, it was regarded as the longest span Suspension Bridge in the world, more than two times bigger than the predecessors’ largest span bridge. However John Roebling passed away in 1869 and handed the project and construction over to his son Washington Roebling who was only 32 years old when this happened.
It took altogether 11 years to complete the build; The two towers consisted of Rosendale Cement, Limestone and Granite, however during the construction process, iron probes that were under the caisson were too deep, so they needed to be fixed. The reason for this is because otherwise there would be an additional risk of ‘decompression sickness,’ so after the alterations the tower base had more than sufficient support.
After the Tacoma Narrows Bridge Collapse in 1940, even though Brooklyn Bridge was still going strong, the bridge was checked for resonant and aerodynamic flutter however they found no faults with the bridge.
Nonetheless, the bridge collapse of I-35W Highway Bridge in 2007 lead to alterations at the ramps of the bridge on each side. Both ramos were widened from two lanes instead of one.
A Random Fact: The wire cables were added with the intention of stiffening the bridge and giving it additional support, however they did not make any difference; the cables are now kept merely for their aesthetics. Moreover, Brooklyn Bridge was commented in a BBC documentary as part of the ’7 Wonders of the Industrial World’.
And then there came the age of Suspension Bridges
Soon after the completion of Brooklyn Bridge, came Tower Bridge in London (1886), George Washington Bridge, New York (1931), Golden Gate Bridge, San Francisco (1937), Humber Bridge, England (1981) and also Akashi Kaikeyo Bridge, Japan (1998) – the world’s longest span Suspension Bridge to date (1,991 m).