Read the text and make a list of the main ideas you should remember as a future bridge designer

The moment the bridge has been built is a celebratory occasion. The official who puts the structure into operation follows the celebration. The State Acceptance Committee is charged with the bridge availability status. Experts in the commission study all the documents and provide an on-site review and visual inspection of the bridge components. They examine them with geodetic devices to locate defects before they turn into a serious problem. The bridge is tested under static (fig. 15.1a) and dynamic (fig. 15.1b) overloading at every structural element. The welding and joints, which can change their initial position under an emergency load, are carefully examined. If the structure meets the standard requirements and the acceptance documents are signed, the bridge is transferred to the possession of the Railway and Motorway subdivisions.

The rules and demands for scheduled and emergency maintenance of R& M ES must be observed according to “Building Specifications” and provide safe operation during their service life of 80-100 years. A bridge supervisor performs all necessary engineering supervision and thorough inspection of long bridges. Short bridges and culverts are inspected by a maintenance supervisor. He or she heads a maintenance crew, which locates and fixes small damage and defects; cleans snow, slush and mud; determinates wear and deterioration of bridge components; fills in the forms and keeps detailed and accurate records of bridge inspections and testing. They also keep a written record of wear-out failures, which need general overhaul.

There are four assessment stages of a bridge condition: from zero to the third stage. The structure zero stage is its standard condition. The next stage means minor failures and damage, which can be repaired during maintenance or general overhaul. The third stage calls for reconstruction or complete replacement.

The Trans-Siberian Railway runs through permafrost areas, and bridges along this main trunk line require costly upkeep. As a lot of ice melts each summer constant maintenance includes track leveling on railroad bridges. In winter, extensive maintenance is also required to combat frost heaving when local displacements of 2.5 to 35 cm occur in roadbeds and bridges.

Bridge maintenance depends on the structure’s carrying capacity. Many R& M ES in Russia were built according to “Building Specifications” issued between 1884 and 1985. Currently the experts evaluate bridges according to superstructure and live load classification, and Building Regulations issued in 1985. When they compare bridge conditions, they draw conclusions about the operational efficiency under a modern live load.

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