A complex reconstruction of the Old Bridge in Bratislava – construction and removal of double cofferdams in the Danube riverbed for carrying out foundations of two bridge pillars

Bridge pillar foundations in a riverbed of any river always stand for a demanding task requiring a careful preparation. The more this is true in case of the Danube River and pillars intended for the oldest bridge in the Slovakian capital city. That´s why the Zakládání staveb Co. paid special attention to the contracted works on two large double cofferdams for foundations of the Old Bridge in Bratislava.

Of the original three pillars in the riverbed only pillar no. 5 was preserved, while pillars no. 3 and 4 were replaced with a new pillar no. 34. All construction works on these P5 and P34 supports were carried out from artificial islands created by mutually coupled sheet pile enclosures with the riverbed sealed by jet grouting. From the excavated spaces within the enclosures was the pillar no. 34 constructed and strengthened the original pillar no. 5.

Due to a tight time schedule of the new bridge construction there was no space for both mistakes and downtimes. All works had to click to the day to prevent delays in the follow-up pillar construction. There has been an existing experience in foundation engineering in this area – in 2004 the Zakládání staveb Co. carried out a dry cofferdam for the foundation of a single pillar of a new arched bridge Apollo opened in 2005. The cofferdam was realised in the Danube riverbed using the jet grouting technology.

 

The new bridge transfers trams, tram-trains and bicycle and pedestrian traffic, connecting the city centre and the Petržalka housing estate. The bridge is made of a continuous truss structure of six fields spanning from 32 to 137 m. The tram traffic is located between truss girders; the cycling and pedestrian paths are situated on the outer sides of the bridge. The supporting structure was assembled on the riverbank and subsequently pushed to its designed position.

 

The whole topic was published in ZAKLADANI 1/2016 magazine