Works Between Giurgiu and Ruse

Last year, on March, the overhaul works at the superstructure and infrastructure of the bridge that crosses the Danube between Giurgiu and Ruse have been started off, and they will be finalized the current year. The designer of the work is ISPCF SA, consultant - TYP SA, and the constructor - CCCF SA, Giurgiu Agency.

The double bridge (road and railways) crosses the Danube at km 488+700. Between the towns Giurgiu and Ruse, has a 2,223.92 m length and it is compound of 38 infrastructures, among which 18 foundations on floating axles (from the 6th file up to the 23rd), and the rest of the files on enforced concrete.
With almost 200 m upstream of the bridge, the Danube is ramified, on the left side being the secondary branch Ara, having a 6.5 m length. The main course of the Danube is separated by this branch by Mocanu isle, which at the middle has an almost 1.5 km width, the maximal width being of +5, +6 m in comparison to the etiage measured at Railway Station from Giurgiu. The analysis that have been performed have issued certain morphological falsifications, which implied, among others, widening of Ara branch due to the "washing" actions of the banks, downstream of the bridge, the evolution of the phenomenon to the bridge, starting from the upstream end of Mocanu Isle, and the widening downstream of the bank located upstream of the bridge; the evolution downstream, on the main course of the Danube, of the existing pit in proximity of the 17th file, producing its erosion and the erosion of the Mocanu Isle on the main course, as well as on the Ara branch, having implications on the erosion of the 17th and 10th files.
In order to stop the falsification process of the river channel and in order to provide the stability to the bridge, starting with 1963 there have been executed local consolidation works, in the proximity of the entrance in the Bazinul Plantelor, as well as on the left bank of Ara branch, besides the 16th file.
There have been also executed brushings of the Mocanu Isle banks, starting with the superior side upstream of the bridge, for the front bank of Ara branch, as well as for the front bank of the Danube.
A special attention has been paid, in year 1972, for the works in the proximity of Mocanu Isle, because the running speed of the water has caused pronounced erosion of the 17th file. In order to stop this disaster the river channel has been covered with anrocaments. Still, the erosion process has started once again, being necessary vast consolidation works, which have been achieved in year 1992.

Work lots for the restoration of the bridge between Giurgiu and Ruse

The consolidation of the foundation files and of the river channel in the bridge infrastructure area
In order to avoid the erosion of the bridge infrastructure Giurgiu-Ruse in the Ara branch area there have been recommended brushing and regularization works on the Danube course - namely, of a bottom sill, downstream of the railway bridge, continuing the existing one. The bottom sill will have the following characteristics:
- the maximal quotation of +8.50 m, the reference level being the Baltic Sea (-4.08 etiage Giurgiu);
- a 100 m length, perpendicularly on the river channel;
- fascine mattresses of 6 x 0.690 x 10 m, each of them stipulated with geo-textile filters;
- stuffing ledge, raw stone of 10-250 kg;
- stone blocks carapace of almost 1,000 kg each.

The replacement of the wooden slippers with pre-pressed concrete ones at the access viaduct of the railways
The main objectives are the replacement of the existing slippers with new pre-pressed concrete ones and the elevation of the embedding level of the slippers so that there will be obtained a 30 cm thickness of the ledge of the crushed stone under the slippers and of the hydro-insulation ledge, having as result the improvement of the safety and comfort conditions during operation.
The above-mentioned works will be executed with traffic shutting down, after the repairing of the degraded concrete plates (treated with XYPEX), the renewing of the hydro-insulation, the treatment of the laying gap and the super elevation of the tympanum of the concrete vat.
The railway on the access viaduct will be achieved with pre-pressed concrete slippers of P1 type, having a slippers end of P2 type, with the exception of the areas where will be located compensation devices (files 4 and 12), respectively the new wooden slippers. Because the slippers for the railway network having as ballast prism allow the assembling of the protection banisters at the ends, the new concrete slippers will be assembled at 60 cm distance between them. The assembling of the track panels will be achieved by shutting down the traffic, on the section having the length of a panel, according to the technical procedure afferent to the execution of the welding of the track will be performed, in the first stage, up to the minimal quotation, and after the assembling of the panels, in the second stage, there will be completed up to the designed level.

The use of the modern compensation devices
These devices are installations, which compensate the difference between the length of the slippers or allow the movement of the slippers in vertical plan, simultaneously compensating the dilatation and comprising the 350-mm of the metallic deck. They have also the role to counterbalance the longitudinal movements of the track, up to the value of 350 mm, resulted from the dilatations or comprising of the metallic deck of the bridge.
For this vast work there are used two types of devices:
a) longitudinal - of AC1, AC2, AC3, AC4, which are mounted on each of the two tracks and have two main pieces: the switch point and the check rail, which are joined at a certain distance in order to compensate the difference of length of the decks through a special system of metallic devices;
b) b) vertical and longitudinal - of AC5 and AC6 types, containing devices that allow displacements vertically and horizontally.

The welding of the track to the bridge
The welding works of the track will be performed during the shutting down of the traffic for maximum five hours, from Ruse to Giurgiu, right after the finalization of works at the viaduct and at the metallic decks.
The new track sections, 49 and 65 types, having an indirect K fastening, with special wooden slippers, having the 0.24 x 0.24 x 2.60 m section, with a 762.02 m length and a very complex system of decks; four of 80 m, two of 160 m and a 86 m deck. The slippers are located at 45 m distance between the axles. But, once with the changing of the existing slippers with new ones, there will be changed the fastening of the slipper to the deck; therefore, there will be assembled angle-bars of 120 x120 x 12 mm, fastened with rivets by the sole of the longrines. The fixing bolts of the slippers will be mounted horizontally, thus improving and enhancing the revision and the maintenance of the railway bridge. The replacement works for the wooden slippers are executed by shutting down the operation on the respective line and implies several stages: the disassembling of the tracks from a railway panel and its temporary placement on the pavement; the disassembling of the existing slippers; the assembling of the angle-bars for fastening of the new slippers (riveting); the assembling of the new slippers; repositioning of the panel-tracks, linked by K fastening.

The overhaul of the concrete deck of the bridge flooring, of the rail joints and the hydro-insulation replacement
Within this lot there will be performed several important works:
- the super-elevation of the tympanums of the concrete vats, which implies welding of the viaduct way and obtaining a crushed rock bed of 30 cm, under the sole of the slipper. For this stage there are necessary the following operations: the partial demolition of the vat tympanum, the assembling of the reinforcement of OL 37 on the super-elevation area of the tympanum and, finally, the assembling of the build-up casing and the pouring of the concrete;
- track works necessary for the introduction and the drawing out from the track of the temporary culverts;
- the drawing out of the crushed rock existing under the culverts;
- the disassembling of the protection decvice, of the existing rail joints and of the current hydro-insulation;
- the preparation and the pouring of the concrete at the decks ends;
- the assembling of the ballast stoppers;
- the restoration of the hydro-insulation on the viaducts, fact that means the cleaning of the support-concrete and its overhaul, the assembling of the hydro-insulation and the completion of the crushed rock up to the slippers sole;
- the treatment of the concrete with XYPEX at the inside and outside of the vat.

The provision of the water drainage from the road system under the level of the supporting elements of the railways
Presently, the collection and the evacuation of the waters from the surface of the roads are provided through devices with drainage apertures, waterspouts and tubs.
While raining, in the area of the bridge where the two communication ways are superposed, the waters collected at the road level are evacuated through the drainage apertures and spread by free fall on the metallic structure, phenomenon amplified by the wind action, fact that leads to the faster corrosion of the resistance structure of the metallic decks.
In order to remedy this inconvenient there has been adopted the solution of collecting the waters and conducting them under the inferior sole of the railways beams, by the adjoining of the existing evacuation tubes to the new collecting pipes, therefore resulting an improved collection and evacuation system of the waters.

The assembling of supervision and maintenance scaffolds for the metallic decks of lattice beams type
In order to inspect and to maintain the decks of lattice beams type 2 x80 m and 2 x 160 m length there will be achieved three types of scaffolds; 2 x80 m, 2 x 160 m - inferior etiage types, and 2 x 160 m - superior etiage.

The endowment with interlocking system (BLA)
There are stipulated; outside works (signals, track circuits, cable networks), works at the self-stopping installations for the bridge track, at the self-stopping cable networks for the track switch on the bridge, of the joint insulating joints, and also at the works at the telecommunication equipment.
The execution of the works within this lot depends on the finalization of others, as: the changing of the rolling track on the wooden slippers (on metallic decks) or on the concrete sippers (on the viaduct), the welding of the tracks and, of course, the implementation of the compensation devices.

The use of the force equipment for the electromagnetic operation of the mobile brake
The elevation of the central deck, with a 86.02 m clearance, in order to provide the free height for the heavy river traffic is performed by telescoping of the bulkhead stiffeners of the railway bridge, by interrupting the railway traffic and by bringing closer the track to the inferior sole of the railway bridge from the road bridge. This operation is performed according to the level of the water, which reduces the height of the traffic gauge. The respective equipment is endowed with control panel, signaling lamps, supplying box, locking-unlocking mechanisms and electrical panel.

The achievement of the signaling equipment of the navigable way
The Romanian party, as well as the Bulgarian party will provide the signaling works that will be executed on the bridge, as well as on the banks. For the navigation on both ways, the signaling on the bridge will be achieved on four clearances: IV/17 - V/18; V/18 - VI /19; VI/19 - VII/20; VII/20 - VIII/21, and will be performed with CH "CFR" signals. There should also be added the fact that the cable electrical network is achieved with cables of 5 x 2.5 sq.m., the panel is located in a cabin on the 18th file, and the guidance and the surveillance of the navigation during execution will be performed by the bodies assigned pursuant to the mutual agreement of both parties.

The provision of the anti-corrosive protection for the metallic decks
First of all, there is cleaned the degraded paint from the metallic deck - there are scrapped, washed with water and caustic soda. The next stage is the primering with a ledge of lead miniu, the painting of the metallic deck, in two ledges, after which there will be made and assembled the suspended platforms.
Referring to the current stage of the works, according to the statement of Mr. Dragos Burlan, the chief of Giurgiu CCCF Agency, the consolidation works of the river channel and the ones for the assembling of the remote control equipment are almost finalized. The same situation is recorded with regard to the replacement of the slippers, the repair of the deck of the bridge flooring and of the hydro-insulation.
Presently, there are performed works at the assembling of the scaffolds meant for the maintenance and at the drainage devices for the rain water, on May, once with the welding of the track to the bridge, this great project is going to be finalized.

Magdalena Fedeles