The construction of bridges: a look through the centuries
Among all designs ever created by man, bridges are among the very first. They were created when it was necessary to cross the river and were valuable. Therefore, the bridges were built of durable material that served for a long time. Nowadays, it is easy to track how the technology of construction of waterways crossings has changed, considering examples from the most ancient to modern bridges.
Arkadik Bridge in Greece – the first example of centuries-old structures
To date, the oldest recognized Greek bridge Arkadik. This is one of those historically significant structures that are still used for the intended purpose. According to historians, there was a military road, and the crossing over the river was built during the heyday of the Hellas civilization in the 13th century BC.
The width of the bridge is 2 meters 50 centimeters, so that not only people could walk along it, but also chariots. It is built of limestone cobblestones without any connecting compounds. In order to create a similar construction, the ancient builders needed to calculate the center of gravity and arrange all the stones relative to this point. Due to the fact that the bridge is arched, the weight of the stones is distributed more evenly, so they can be held without additional bonding agents.
On the support – the foundation, which is formed by rectangular cobblestones – 2 bearing pillars are built. They expand so that their tops almost touch each other. At the place of their connection a pile of stones is laid, tightly covering the gap between the columns. Further layers are superimposed already on this structure. Sophisticated design allowed the bridge to remain almost in perfect shape.
British Tarr Steps – the path of large flat boulders
A newer bridge – the Tarr Steps in England – is a path of large boulders. Flat plates are located on a lined stone base. It is difficult to say about the date of the construction, as with constant contact with water, any signs that could prompt the age of creation were erased.
On the construction of this transition is a legend. Such boulders could not be brought to this place, so many believe that the “waterway” was built by the Devil himself, who wanted to walk on water just like Jesus. Local residents, who learned about the idea of Satan, tried to chase him away, but they could not do it. Then they made a deal with the Lord of the Underworld: the bridge can be used at any time. However, the Devil can lie down here to sunbathe, then any traveler will fall into his captivity. Therefore, you need to be careful and make sure before going to if Satan has not lurked on the walkway.
Ancient Russia: from rafts to arched bridges
Most of the deep rivers in ancient Russia were used as trade routes, so they were not blocked off by bridges until the 17th century. On calmer rivers and ravines, bridges were built, more like rafts of 2-3 layers of logs. They descended only when moving from one side to the other, and in most cases were part of the wall that protected from the invasion of enemies. However, such constructions have not reached our days.
Beginning in the 17th century, namely, with Sofia Alekseevna’s reforms, new arched bridges appeared that repeat European patterns. One of them – Palace Lefortovo. It was built, according to various sources, in 1777 or in 1781-1799.
Palace Lefortovsky Bridge
Also in Moscow there is also Rostokinsky aqueduct across the Yauza River (the so-called “Millionth Bridge”), which was built in 1780–1805 for water supply. Now he is walking.
The complex of buildings of the summer residence of Catherine II includes the Big Bridge (1778–1774) over a ravine. It is the largest surviving bridge of the XVIII century. Architect V.I. Bazhenov.
Big bridge over the ravine at the summer residence of Catherine II
Bridges today: construction technology
Today, the most popular ways of building bridges are:
This option includes the tradition of the construction of aqueducts. The bridge resembles an arch with columns fortified on the banks.
This option is used if the gorge is deep and narrow. By design, it resembles a rope, each end of which is tied to a base.
This option is used to create long bridges. It resembles several girder bridges connected into one. At an equal distance, columns are installed on which the warp segments are fixed.
This is a type of suspension bridge, which consists of one or more pylons connected to the road by means of steel cables – cables.
Nowadays, you can also see unusual structures, repetitive structures of ancient bridges. However, there are more popular technologies that are used in the construction of transitions in large cities.