Floating bridges, depending on their floating supports, can be raft, pontoon or scuba. Raft bridges are now very rare due to their low load capacity. Pontoon floating bridges, the supports of which are hollow closed boxes (pontoons) made of wood or metal, are inconvenient to operate due to the difficulty of inspecting and repairing them. The most common types of bridges with large load-bearing capacity are those on floating supports in the form of barges or pontoon boats.

A special feature of floating bridges is the seasonal nature of their work. With the onset of freeze-up, they are removed to backwaters or to the shore, protected from ice drift and floods, and if they are used during the winter, then they are taken to backwaters during the spring ice drift. Floating bridges require large expenses for the maintenance and repair of the floating part. The main element of a floating bridge is its floating part in the form of floating supports and spans (structure) resting on them. The floating part usually covers the main part of the river width, at which, at the lowest water level, a margin of 50 cm is provided from the river bottom to the bottom of the support when passing vehicles across the bridge. The floating part of the bridge is usually formed from individual links that have one or more floating supports with lining, and is secured with anchors against drift by water and wind. To allow passage of ships, a drawbridge consisting of one or several links is constructed. The shore part of the bridge is an overpass simplest design in sections of the river where the depth is insufficient for the construction of floating 262 pores. Usually the coastal part is adjacent to the ramps to the shore. To connect the floating and coastal parts, an ice-moving structure is used, which changes its level depending on fluctuations in the water level in the watercourse.

Although the construction of floating bridges is simpler and cheaper than permanent bridges, their operation is more complex and involves significant materials and especially labor costs. Floating bridges require round-the-clock duty of a team of workers to ensure traffic safety and timely elimination of all defects, damage and malfunctions, as well as ensuring normal navigation on the river. Constant supervision is needed over all elements of the bridge - floating supports, anchor devices, structures, span structures of transitional coastal parts and approaches to the bridge.

When maintaining floating bridges, the main attention should be paid to the floating supports. Daily inspection of the supports from the inside and outside checks the condition of the support and the amount of water inside. Normal quantity water in the support should not exceed half the height of the digging. Excess water must be pumped out in a timely manner. If the supports are damaged and a leak appears, the causes must be determined and eliminated.

In wooden floating supports, defective places (cracks or holes) are repaired with caulk or wooden plugs made of non-splintering wood. If the defective areas are not immersed in water, caulk from the outside from a boat or other floating craft. Cracks and holes in the casing located below the water level can be sealed from the inside.

To protect floating supports from rotting or rusting, it is necessary to ensure ventilation of their internal cavity by eliminating hatches in the pontoons. All longitudinal trusses, frames, transom frames, as well as load-bearing elements of the internal structure must be inspected daily, checking the tightness of the joints and connections, and any defects found must be immediately eliminated. When rot appears, the affected wood is removed and replaced with healthy wood soaked in an oily or water-soluble, difficult-to-wash antiseptic.

Strict requirements for the maintenance of floating supports force the operation service to keep on shore or on the water, not far from the floating bridge, spare floating supports, and, if possible, individual links of the floating bridge.

To ensure the required position of the floating part of the floating bridge (from drifting by current or wind) during operation, the floating supports are secured with ropes or cables to dead bodies, anchors, piled bushes or trees on the shore. Typically, floating supports are secured on the upstream side to prevent them from being carried away by the current. When the river flow is weak, where the floating part can be blown away by the wind in the direction opposite to the flow, it is also secured from the downstream side. Floating supports, located not far from the shore, are secured to large tree trunks or bushes of piles driven on the shore, and the remaining supports are secured to anchors. On small rivers it is sometimes possible to secure the floating part without using anchors.

The securing ropes must have an angle to the direction of water flow of no more than 35°. The distance from the anchor to the floating support (Fig. 156) should be 10 times the maximum depth of water in the river. As a rule, steel ropes are used; hemp ropes, due to their very short service life, are used only in exceptional cases. The ropes are secured to the anchor and winch installed on the floating support.

If the anchor is pulled from its bridge, the floating part of the floating bridge becomes distorted. If the anchor is pulled off slightly, the rope is pulled up with a winch, but if it is pulled down significantly, it must be thrown back into the design position. In the event of a systematic change in the position of the anchors, their number must be increased or replaced with heavier ones.

The work on maintaining the transition parts includes constantly ensuring smooth entry and exit from the floating bridge. When the amplitude of fluctuations in the water level in the river is up to 1.5 m, the transition part consists, as a rule, of one span, hingedly supported at one end on the extreme coastal trestle part, and at the other on the floating part of the bridge. The transition part in this case is a simple beam system with a span of up to 6-8 m. The ends of the purlins usually rest on the outermost floating support, causing its overload and significant settlement. Therefore, the outermost floating support (pontoon or pontoon) must have a greater load-carrying capacity than the rest.

Rice. 156. Scheme for securing a floating bridge on a wide river

Often, floating bridges are built across large, high-water rivers, where the vibration amplitude can exceed 5 m. In these cases, it is necessary to install transitional spans with through trusses or rest them on special pile supports (Fig. 157), equipped with lifting devices (hoists or jacks). With the help of these devices, raising and lowering the transition parts ensures smooth entry and exit from the bridge.

The maintenance service regularly monitors the interfaces of transition spans with floating and permanent supports. If the water level changes, the lifting beams are raised or lowered accordingly with hoists or jacks, giving the transition part an outer slope (no more than 80°/oo) - The greatest difficulties in maintaining the transition parts of floating bridges arise in the spring when ice drifts pass. Before ice drift, the floating part and span structures of the transition parts are removed to a safe place, but the tower supports of the transition spans remain and are protected from ice drift. There are three known options for preserving the supports of transition spans. When the ice drift is relatively weak, the tower supports are protected with ice cutters, and when the ice drift is strong, they are made collapsible. In the latter case, before the ice drift is allowed to pass, the upper part of the supports is dismantled and, together with the lifting devices, is removed to a safe place. The remaining part of the support must be such that it will not be damaged by the lowest ice drift.

Sometimes transition parts are arranged with two independent entrances with a height difference of approximately 1.5 m. The installation of several entrances makes it possible to reduce the length of the transition part to one span and simplify its design.

Rice. 157. Schemes of the multi-span transition part of the floating bridge and the profile of water level fluctuations.
A - level fluctuation amplitude

Moving the entire floating part from one entrance to another when the water level changes does not present any particular difficulties - the entire floating part is pulled upstream or lowered downstream. If the floating support is a dinghy or pontoon, then the height of the dry side, i.e. the height from the water level to the top of the floating support, must be at least 50 cm. Reducing the height of the dry side can lead to the floating support being overwhelmed by water with a loss of the load-bearing capacity of the bridge. Therefore, the operation service must have a schedule for passing temporary loads on the bridge, taking into account their weight and dimensions.

When passing vehicles whose weight is close to the standard, it is necessary to strictly control the distance between these vehicles, as well as ensure the passage of single, especially heavy vehicles in the middle of the bridge in one-way traffic. After the passage of heavy vehicles, it is necessary to inspect all bridge structures. On floating bridges, sudden braking and turning of vehicles is prohibited. To regulate traffic on the floating bridge, there must be barriers on both banks and the most experienced workers must be on duty.

To quickly and accurately set up the span and put it back in after ships have passed through, it is necessary to equip the spreader with electric motors of sufficient power. Electric motors are installed on shore in a special room or on the first floating support of the drawbridge.

Usually, with the help of one mechanism, the wiring and reverse installation of the adjustable link are carried out (Fig. 158). In this case, a traction mechanism is installed on the shore, consisting of an engine, two drums rotating in different directions and two cables (from the drums), connected to the first floating support of the draw span of the floating part of the bridge. Sometimes two traction mechanisms are installed on the first floating support of the adjustable

link, with one working on the bridge layout, the second - on aiming.

In some cases, when the traffic intensity on the road and river is low, the bridge is drawn and entered using a gate installed on the first floating support of the draw link.

In most cases, floating bridges are operated when the river is free of ice, and in winter they are raised and removed to a place safe from spring ice drift, for example, in backwaters on the river in which there is no ice drift, or the water level in which is 25 cm lower than the draft of the floating support from of their own weight, or are pulled ashore above the level of the greatest ice drift. In this case, the movement of vehicles in winter is carried out along an ice crossing.

Rice. 158. Layout and alignment diagram of the floating bridge span: 1 - block; 2 - winch; 3 - movable span structure

When cold weather approaches, as well as before the passage of floods and ice drifts, it is necessary to organize observation points connected to the bridge, taking into account the characteristics of the river regime. More often, such observation points to obtain information about the movement and accumulation of ice, the appearance of slush and grease are installed upstream 5-10 km, and sometimes further.

When the current is weak, slush easily accumulates near the pontoon bridge, freezing to the piles, floating supports, ropes, clogging the live section of the bridge, forming jams, creating additional load and thereby reducing the load-carrying capacity of the bridge. The resulting jams and jams restrict the river bed and increase (sometimes several times) the pressure on the floating supports, damaging them.

During the first frost, thin ice forms on the river from small pieces (lard) moving with the flow (autumn ice drift). Thin young ice damages the skin of floating supports and easily cuts even steel ropes with its edges. Fat, especially when the river flow is weak, freezes to the floating supports and creates the risk of jams.

To keep bridges in good condition, special measures must be taken.

When sludge, grease, and sneshura appear on the river, it is necessary to systematically (with shovels, crowbars or ice picks) clear the sides and bottoms of floating supports and anchor ropes from freezing ice. In some cases, when large ice floes appear, blasting operations are carried out at a distance that guarantees safety. To protect the side plating of wooden floating supports from cutting thin ice It is effective to cover them with boards either only from the bow or along the entire perimeter of the floating support. In this case, additional plating is provided within the limits between the waterlines corresponding to the unloaded and maximum loaded state of the bridge. To pass accumulations of slush, grease and slush, as well as large ice floes, the size of which exceeds the clear distance between the floating supports, it is necessary to separate the spans of the floating part of the bridge.

If not all floating supports are included in the draw span, then to protect the remaining ones it is necessary to install floating booms to guide the ice floes into the bridge opening. Booms constructed from single or paired logs must be securely fastened.

During the freeze-up period, the water level fluctuates. A decrease in level causes the ice to sink, tearing it away from the shores and, if at this time the floating supports become frozen in the ice, they can be crushed. Sudden fluctuations in ambient temperature can also lead to crushing of floating supports. To prevent the destruction of floating supports during this period, it is necessary to systematically remove ice around the supports and anchor ropes throughout the winter period.

To increase the productivity of work on ice chips near the supports, pipes with holes for air passage are laid along the river bottom. Air enters the water through the holes, rises up and breaks the ice. This device has great productivity.

There are known cases of floating supports freezing into ice on large navigable rivers, where the water level is most stable and the floating supports are metal. When operating floating bridges with frozen floating supports, with the onset of spring thaws, it is necessary to promptly ensure that ice chips around the floating supports are removed.

Studying the origins of Kyiv, you can find documentary references to the crossing of the Dnieper in the area of ​​interest. I offer a selection of drawings and photographs confirming the very possibility and actual implementation of such crossings.

Similar structures have been known since ancient times. Herodotus (5th century BC) reports that during the campaign to Scythia, the Persian king Darius (522-486 BC) to cross his army across the Bosphorus and Danube ordered ships to be placed side by side, on top of which they were laid wooden flooring. His successor Xerxes (486 - 465 BC), who undertook a campaign against Greece, when constructing a similar crossing across the Bosporus, ordered a rope to be twisted and pulled across the strait to keep the ships from being carried away by the current.

Documents were found about the Kyiv crossings, but first, as always, Rome marked itself in history.

The figure shows a diagram of the construction of a simplified pile bridge.

Roman technology is often said to be synonymous with military technology. The world famous roads leading exclusively to Rome were not built for everyday use, they were of military importance. By definition, no “traffic jams” could arise on them. Thanks to roads, the legions quickly reached their destination and returned just as quickly. Roman pontoon bridges served the same purpose.

This is the brainchild of Julius Caesar. In 55 BC. he built a pontoon bridge over the Rhine. The length of the bridge was about 400 meters. The Rhine was traditionally considered by German tribes to be their defense against Roman invasion. And here you go.

The bridge was built in just ten days, using only lumber. Caesar wanted to cross the Rhine and he did it.

The pontoon bridge was held across the river by cues (poles) driven into the bottom of the Dnieper. It consisted of two parts. One part connected the left bank of the Dnieper with Rybalsky Island, which in those days was longer, the other was thrown across the Pochaina River and connected the island with the right bank.

The diagram shows a log deck with piles (cues) sticking out of the water, to which the boats located under the deck are tied. The adjustable section is located on the right bank of the Dnieper. To allow ships to pass, it was pulled up to a pile, which was further away from the transport than the others.

Bridges over the Moscow River. 1476

The presence of many bridges across the Moscow River within the city is confirmed by Ambrogio Contarini, the Ambassador of Venice: “The city of Moscow stands on a small hill; the castle and the rest of the city are wooden. A river called Moscow runs through the middle of the city and has many bridges. The city is surrounded by forests." The ambassador was passing through Russia and admired Moscow bridges from August 1476 to January 1477.

Our artists did not stand aside either. A.M. Vasnetsov, “The Moscow Kremlin under Ivan III.” http://www.bibliotekar.ru/kVasnecovApp/15.files/image001.jpg

This bridge was rebuilt many times, having its own name - Moskvoretsky.

Centuries after Contarini’s visit, on May 28, 1987, when the USSR celebrated the next Border Guard Day, 19-year-old German Matthias Rust landed on the modern Moskvoretsky Bridge in a small Cessna-172 sports plane. Rust, without an entry visa, crossed the Soviet border, flew 800 km over the territory of the USSR and landed his plane in the center of Moscow.

The plane turned left and descended to land between the Kremlin's Spasskaya Tower and St. Basil's Cathedral. Rust failed to land the plane directly on Red Square; there were many people on the square. Having made another turn over the Rossiya Hotel, he descended, landed in the middle of the Moskvoretsky Bridge and taxied onto Vasilyevsky Spusk.

Bridge over the Oka River, Nizhny Novgorod.

How wonderful it is that old postcards are preserved in family archives.

In the center of the picture on the Oka and Volga arrow you can see the Alexander Nevsky Cathedral, and on the river there are many ships in front of the pontoon bridge.

Bridge over the Neva, St. Petersburg, 1727

In total, there were 11 large floating bridges in the Neva delta in St. Petersburg. The first of them is St. Isaac's. It was brought in in 1727 on the orders of Prince A.D. Menshikov, the de facto ruler of Russia at that time. The bridge connected Vasilyevsky Island with the left bank of the Neva a little west of the Admiralty - where St. Isaac's Church stood, from which the bridge got its name.

Under the leadership of the ship's master, bombardier-lieutenant F. Palchikov, the St. Isaac's Bridge was rebuilt in 1732. It consisted of a number of barge-decks, anchored. Purlins and flooring were laid on the barges. To allow ships to pass through, the bridge had movable parts in two places.

Everyone who used the bridge was charged according to the established tariff. From pedestrians - 1 kopeck, from carts - 2 kopecks, from carriages and carriages - 5 kopecks, from 10 small livestock - 2 kopecks, from ships (with a drawbridge) - 1 ruble. Only palace carriages, palace couriers, participants in ceremonies and fire brigades were allowed through for free. The toll was abolished in 1755.

Isaac's Bridge was built annually in the summer season for 184 years. On June 11, 1916, a spark from a tugboat passing along the Neva ignited and burned down.

Granite foundations on the side of the University Embankment and on the side of Dekabristov Square are mute witnesses of the St. Isaac's Bridge that once existed here - the first floating bridge across the Neva.

Pontoon bridge in Orsha, 1895

In past centuries in Russia, pontoon bridges connected the shores not only in the capitals.

In the picture the Dnieper is not far away, and this is the Orshitsa River.

Source: http://orshagorodmoy.info/forum/24-170-1

Military bridges of Kyiv in 1941

The Dnieper has known many bridges in different centuries.

During the retreat of the Red Army in 1941, all the beautiful bridges across the Dnieper were blown up.

Below are photographs taken presumably by a German non-commissioned officer, the owner of the album, which was picked up by one of the Kiev residents after the Nazis retreated from Kyiv soil. Photo source: http://reibert.livejournal.com/50011.html

The length of the bridge is 110 m, load capacity is 20 tons.

In Russia, you can order a floating road bridge only from a few manufacturing companies, and our “Perfect Plus” is one of the best among them. Despite the fact that floating bridges, which are a type of pontoon bridge, are mainly used for military purposes, they can bring great benefits to the national economy. On non-navigable rivers, the construction of floating bridges can be a worthy alternative to expensive structures on permanent supports. The broad capabilities of such structures are confirmed by the decision of Defense Minister S. Shoigu to build a floating railway bridge across the Volga near Yaroslavl. The total length of such structures erected in the regions by railway troops will be more than 5.5 km. A low-water floating bridge can be used to significantly reduce the length of the route when removing crops, as well as when reconstructing or repairing an existing river crossing.

Advantages and disadvantages of pontoon bridges

The main advantage that each pontoon bridge has is the ease of its transportation to anywhere in the country. Delivery to the installation site can be carried out by rail, road, water or air transport in a disassembled state. After all elements arrive at the assembly site, installation and commissioning of the crossing can be carried out in a short time. Besides:

• There is no need to conduct a study of the structure of the river bottom and install supports;
• If necessary, the structure can be moved over a considerable distance without complete disassembly, which allows you to use one set to solve similar problems one by one;
• The design can be used to quickly solve transport problems in disaster areas;
• It is possible to install floating bridges during the construction of industrial facilities in sparsely populated areas, for operation until the construction of a permanent structure;
• Pontoon bridges can be designed and manufactured according to the wishes and technical specifications of the customer.

A significant disadvantage of floating bridges is the impossibility of their effective operation during spring floods or ice drift. Increased caution is required when using them during strong winds. They also create big problems for navigation, so additional approval for their construction is required on navigable rivers. The problem can be solved by withdrawing several ferry links while a convoy of ships passes through.

Classification characteristics of floating bridges

1. By period of use:

• Permanent. They require increased attention during floods and ice drift, which does not allow their widespread use throughout Russia, but are widely used in regions with a mild climate;
• Seasonal, differing from permanent ones in that they are dismantled during the descent of flood waters and ice drift. The construction of floating bridges, even if they are regularly dismantled, is much cheaper than support bridges;
• Temporary, used during the construction of capital bridges, as well as military operations and rescue or emergency restoration work.

2. By purpose:

• Pedestrian;
• Road;
• Railway;
• Combined, as a rule, all low-water floating bridges can be used to move not only vehicles, but also pedestrians.

3. By design features river part:

• Cutting system - implies the use of barges with large lifting capacity. Each span is covered by one beam. Flooding of any of the barges (pontoons) puts it out of action;
• The continuous system is much more durable, since the span rests on several pontoons. A flooded pontoon can be replaced after traffic on the bridge is stopped;
• The hinge system is the most durable and reliable. A flooded pontoon can be replaced without stopping traffic.

The sale of a floating bridge, as a rule, is carried out only after the many nuances of its use have been clarified. The customer must know exactly the required load capacity, the width of the river and the structure of the bank at the installation site, as well as the maximum amount of change in water level.

Despite the fact that the construction of pontoon bridges takes a short period of time, their operation requires constant supervision by specialists. Especially during floods or ice drift. The specialists of our company “Perfect Plus” conclude contracts for the maintenance of floating bridges of our own production and those purchased from third parties. Not only load-bearing structures and pontoons are subject to inspection and integrity control, but also anchoring systems that are invisible from the outside and experience significant loads. Timely maintenance of pontoon bridges by specialists significantly extends their service life. Particular attention should be paid to integrity protective coatings underwater part of pontoons and elements of hinge joints.

Metal bridge structures

The bridge does not install itself. Shoreline equipment, power supply and housing for maintenance personnel are required. All necessary metal structures can be ordered from this company. Supply from one source is always preferable to searching for different suppliers.

Bridges Köthe Rainer

What is a floating or pontoon bridge?

What is a floating or pontoon bridge?

In 490 BC. e. A famous battle took place in Marathon, located near the ancient Greek capital of Athens. After lengthy wars, the Greeks finally managed to defeat the Persians, whose army was led by King Darius from the Achaemenid dynasty.

The army of the Persian king Darius crossed the Bosporus across the bridge, laid on anchored ships stacked side to side.

At this time, there was the first mention in history of a remarkable technical achievement. In 493 BC. e. the Persian king Darius made a campaign against the Scythians, transporting his army across the Bosphorus at the narrowest point of the strait, where the width was 700 m. He did this along the first floating bridge: a wooden deck was laid on anchored ships, fastened side to side. Less fortunate was the Persian king Xerxes, who 13 years later set out to cross another strait in the same way - the Hellespont (now the Dardanelles). A sudden hurricane scattered the ships and destroyed the almost completed bridge. The angry Xerxes ordered the builders to be beheaded and the sea to be punished - to flog it! A second bridge was built with 700 ships tied together with ropes and placed on heavy anchors. The roadway was made of beams covered with compacted earth, with a barrier on the sides to prevent timid horses from falling into the water. It is believed that a huge army crossed this bridge - 700,000 horse and foot soldiers, but despite this, Xerxes was still defeated in the battle with the Greeks. Many military leaders used bridges mounted on ships or pontoons - simple floating boxes - to quickly transport a large army across a water barrier. The Carthaginian commander Hannibal crossed the Rhone in this way, Alexander the Great crossed the Asian river Oxus, and the Roman emperor Caligula ordered the construction of a pontoon bridge in the Bay of Naples, only to boast that he had “ridden a horse across the sea.”

Floating, or pontoon, bridges were also built for peaceful purposes, if there were not enough funds to build a permanent, strong crossing. Thus, at the beginning of the last century, bridges across the Rhine appeared near Karlsruhe, Speyer and Cologne, which were even used for railway transport. However, such bridges had to be regularly opened to allow passage of ships traveling along the river; they suffered so much from strong floods and ice drifts and were eventually replaced by permanent bridges.