The log is not a log, but still there are bridges erected already in the VI century BC by the ancient Babylonians. Then the main building materials were wood and stone. The world's first iron bridge was built in England in 1779. Around 1818, they learned how to suspend bridges on chains, and after 42 years concrete bridges appeared. Reinforced concrete came to bridge construction even later - at the beginning of the next, XX century. And after the Second World War, they learned to lay pre-stretched cables in concrete, after which flights over 200 m in length became commonplace. Today, just a long bridge, to be honest, is not too surprising. It is more interesting when a heavy span can move, and not in the same way as drawbridges familiar to Petersburgers. The bridge builders, who were tasked with passing ships with high masts along the rivers, used a variety of designs and mechanisms. They managed to turn the span around a vertical axis, lift it up parallel to itself, fold it like a screen, roll it to one side, roll it into a roll … and drown in the river under the keel of passing ships. However, it is better to see once than read a hundred times.
Folding bridges are being led by engineering troops: tractors with pontoons dashingly drive up to the crossing, in a matter of seconds the sections folded in accordion are laid out. But in Kiel (Germany) a similar screen - Hornbruecke - was installed permanently. This steel bridge with a 25.6 m long wooden roadway is designed for pedestrians and cyclists. Although with a width of 5 m, two cars would have completely left here. But - it is impossible. Nevertheless, almost 20 million Deutschmarks spent in 1997 were not wasted: the building became a city landmark and attracts curious people 12 times a day, when the bridge is bred for 15 minutes.
In Bilbao, this structure, built in 1893, is called the Biscay Bridge. But is it a bridge? Or maybe a ferry? A cabin 14 meters long and 10 meters wide, like a cable car, carries up to six cars from coast to coast in a minute and a half and 30 euro cents. But there is an alternative to more expensive. For 5 euros you will be lifted in an elevator to a 45-meter height, and there you can walk along the pedestrian bridge to the next elevator, which is already going down. During the civil war in Spain, a unique bridge was destroyed in order not to miss the troops of General Franco, but in 1941 it was rebuilt, and in 2006 UNESCO recognized the bridge as part of the world cultural heritage.
At each end of the Corinth Canal (separates mainland Greece from the Peloponnese) stands on a submersible bridge. God forbid being there in a car when the bridge is lowered using a cable system! Above the canvas will be an eight-meter water column. Passing ships of this depth are quite enough.
When the spans of Europe’s highest drawbridge - the Gustave Flaubert Bridge in Rouen - are raised 55 m, you cannot stay on it in the car or on foot with a camera. What a pity, because what a view! But even in the lowered state, 10 m remains to the water. The length of the bridge is all 120 m. It was built in 2008.
Inclined bridge is a real rarity. The span is not straight, but curved in the form of an arc: if you tilt it to the side, a passage for ships will open. The Millennium Bridge was built in 2001 in Newcastle (England). Eight electric motors with a total capacity of 433 kW overturn his canvas at 45 ° in 4.5 minutes. The construction, although it is intended only for pedestrians and cyclists, is rather big: length is 126 m, height in the raised state is about 50 m. And the weight is decent - as much as 850 tons!
Drawbridges surprise not only over the hill. They can be found in Rostov-on-Don and Kaliningrad (railway), Astrakhan (one railway track and two lanes for cars). The list is incomplete.
Opened in 2001, the Al-Firdan Bridge across the Strait of Suez is the longest junction in the world. Its two sections, each 320 m long and weighing 5000 tons, rotate 90 ° in 15 minutes. The axes of the sections are asymmetrical: 170 m above the coast, 150 m above the strait. Therefore, there is a counterweight on the short shoulder. It’s a pity that you can ride the bridge only by train.
In London there is an unusual, perhaps even unique foot bridge in the business center of Grand Union Canal. Its design was invented in 2004 by the architect Thomas Heatherwick (and received an award for it!). With the help of hydraulic cylinders, the canvas bends like the tail of a scorpion, and in three minutes it is folded into an octagonal roll. The length of this pedestrian span is only 12 m, and you can watch the amazing sight on Fridays, at noon.