VII International forum
“Marine Industry of Russia”
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«President-Hotel»
Department of affairs of the President of the Russian Federation

Moscow, 24, B.Yakimanka Str
24-25 May 2017
 
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More on pontoon bridges

One of the earliest mentioning to bridges which can be called pontoon refers to 480 B.C. The bridge made of boards laid over ropes and covered with earth was built by the army of Xerxes to cross the Dardanelles. Hundreds of ships served as floating pier of the bridge. In Rus, pontoon bridges were called live. The first information refer to the XII century although they for sure were built before.

Here, the longest operating pontoon bridge is to be mentioned. It crosses the lake Washington and is called The Second Bridge. Its floating part is 2291 m long and the total length is 3839 m. In Russia, the longest pontoon bridge is a road bridge over the creek of Amur near the village Osinovaya. Its length is 746 m. Pontoon Bridge Construction.

Pontoon bridges consists of several parts: approach, easement and floating section. The floating section can be made of timber, metal or reinforced concrete. Lately, artificial materials have been used very often. Floating piers are made of timber (flat-bottom boats, flotation rafts), metal or reinforced concrete. Today, new pontoon constructions exist – metallic casing filled with light polyurethane. Such pontoons stay afloat even when being damaged. To prevent wind drift, longitudinal and lateral restraints fix bridge components.

Such bridges are used for crossing those water bodies where loose ground, deep water or other reasons impede or even make impossible construction of capital bridges. Since the construction of a temporary pontoon bridge takes little time, they are also irreplaceable in rescue missions or military actions.

As for permanent pontoon bridges, they can be constructed within several months. In Russia, small bridges are built in the countryside or on light traffic roads. Presence of large water barriers makes it necessary to build advances design bridges. Thus, there is a project on construction of a pontoon bridge between the continent and Sakhalin island.

Modern pontoon bridges can be pedestrian, road and railroad.

A railroad pontoon bridge is a construction able to bear significant loads and having high capacity. Several years ago, a revolutionary railroad pontoon bridge MLZhVT was introduced in Russia. The new ribbon bridge differs in simple assembly, much less number of bolt joints, and, since the rails are sunk into the paving, it can be used not only as a railroad bridge, but also as a road one. The most has no wooden components and its estimated service life is a few scores of years. The bridge ensures crossing up to 543 m long. Also, two shorter bridges, 3-4 piers or a couple of pontoons can be made of its package.

Features of Pontoon Bridge Design and Construction

Pontoon bridges cannot be built anywhere. High current speed (over 3.5 km/h) and strong ice drift impede their construction. However, there were built some bridges over the rivers with high current speed and strong freshet – the bridges are drawn for the ice drift period. Also, an aperture of a bridge is provided in the construction of bridges built over navigable water bodies.

Pontoon bridge design has its own features. As opposite to capital bridge construction, this sector is regulated by a less number of statutory acts and standards. Indeed, there are no stringent standards here. On the one side, instructions require to size the ice floe by the length of the largest bridge span, on the other side, it is specified that it is to be sized by the river width during ice breakup. The other manual recommends to define ice floe size as equal.

Bridge design and construction always sparks intense interest at various transport forums. Construction of pontoon bridges becomes prospective owing to traffic enhancement, and profitable owing to accumulated experience and innovations. IABSE (International Association of Bridge and Structural Engineering) financing international congresses and symposiums encourages sharing of experience in the field of design and construction of pontoon bridges.

Organizations engaged in pontoon bridge construction face various difficulties. First of all, it is the seasonal nature of works. Here, water body features are to be taken into account (time and level of water stand, various hydrological parameters of the annual hydrological regime). Then, it is need for construction of a broadland protecting the bridge after ice drift drawing off, which raises the price of the bridge. Here, the nature of ice drift becomes a definitive requirement. When designing and constructing pontoon bridges, ice conditions are to be given more attention. Despite the absence of adequate regulative base, the accumulated practice of the ages ensures construction of reliable and safe pontoon bridges.

 
 
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