Serbian Railways Infrastructure requests inspection of condition of New Rail Bridge with proposal for rehabilitation project – It is uncertain whether and to what extent traffic will be reduced over this sole link on the Sava to Prokop

A little more than half a year after the Serbian Railways Infrastructure company previously announced a public procurement procedure for a detailed inspection and testing of the New Rail Bridge on the Sava in Belgrade, which was built almost half a century ago, this procurement has been announced again.

The subject of the project assignment is 557.94 m of steel bridge construction, without access structures. The project assignment will be divided into five parts: review of the complete structure, preparation of control static calculation, preparation of rehabilitation projects based on the review and control static calculation, examination of the bridge and limitations of use.

As it is added, the Serbian Railways Infrastructure is obliged to ensure the presence of representatives as necessary, as well as to close traffic according to the previous agreement, whereby, as emphasized, it is necessary to avoid closings as much as possible (especially of both tracks). The disconnection of the voltage at the closed tracks is taken for granted, it is added.

When inspecting the steel structure, special attention will be paid to visual inspection of welds (in case of observed damage, additional testing of corner welds - with penetrants, i.e. testing of butt welds - with ultrasound), visual inspection of assembled screw connections (extensions) and control of tightening force according to the principle of random sampling, on the state of corrosion protection, especially zones with an increased degree of unwanted effects, as well as on taking samples from the main support and pylon and testing them on tightening.

A visual inspection of all visible parts of the concrete structure of the pillars is also required, including an inspection of the architectural elements. As it is specified, according to randomly selected places and the need, testing of the surface hardness of the concrete by non-destructive methods, for example using a Schmidt hammer, etc. is required.

– Determining possible cracks, i.e. their width, is also required, with the use of appropriate templates and measuring instruments. In addition, it is also very important to inspect the anchors and determine their condition and possible involvement. During the inspection, it is important to pay attention to other possible irregularities that are observed, such as water penetration or accumulation, the existence of outdated or incorrect technical solutions, and the like. So, those irregularities that are not directly related to structural elements, but have an impact primarily on durability – it is emphasized in the documentation.

As for determining the condition of the cables along their length, it is, as pointed out, the most delicate step in the inspection of the bridge structure in question and can be divided into two subgroups - the visual inspection of the cables along their length and the determination of the condition of the wires inside the cables (there are 240 to 290 pieces per cable, all Ø7mm run in parallel).

Based on all that, a report on the inspection of the complete steel structure of the bridge and visual parts of the bridge pillars is required.

A report on the inspection of all cables individually (64 pieces in total) and a description of their condition is also requested.

A report on the geodetic observation of the bridge is also requested, with a presentation of all periodically measured values and conclusions on the behavior of the observed elements.

As part of this public procurement, the development of rehabilitation projects is requested on the basis of inspection and control static calculation.

– Only on the basis of the results of the control static calculation will it be possible to make proper judgment on whether the focus will be only on rehabilitation or whether rehabilitation and strengthening of elements will occur or even strengthening of elements will prevail – the documentation emphasizes.

Restrictions on use

As pointed out in the tender, it would be optimal if possible restrictions on the use of the bridge (for example, only one train is allowed on the bridge at a time or similar) are established only after the control static calculation, when all the mentioned inspection reports have been prepared.

– However, limitations could occur, that is, they could be stated as necessary and justified in any of the phases described here. The inspectors are obliged to inform the client in a timely manner about the observed circumstances of importance for the load-bearing capacity and usability of the bridge structure, in order to enter into the process of possible additional tests, taking measures and the like – it is noted in the documentation.

As can be seen in the documentation, the total term for all phases of the work is about one year.

Offers can be submitted until January 15.

More details (in Serbian) can be found HERE.

Infrastruktura Železnice Srbije Beograd

New Rail Bridge Belgrade

inspection of condition of New Rail Bridge in Belgrade

Prokop