Swimming in the Waldschlößchenbrücke
The floating of the Waldschlößchenbrücke , which crosses the Elbe in Dresden , took place in December 2010 in a special, not common way. More precisely, it was the floating of the steel structure of the river bridge to its final place between the already assembled foreland bridges .
initial situation
Delay due to lack of planning approval procedure
When construction work on the 636 m long Waldschlößchenbrücke finally began in November 2007 after the various delays caused by the Dresden bridge dispute , the plan was to float the middle section of the bridge in early 2010. Since the protected Elbe ground had to be dredged for the pontoons and the city had not obtained the necessary planning approval decision in time, the floating had to be postponed until the end of 2010. The shift by almost a year was necessary because the water level of the Elbe was only allowed to fluctuate by a maximum of 5 cm during the shifting of the central part from the bank to the pontoons, a state that only changes in winter and in close cooperation, especially with those on the upper reaches of the Czech dams located on the Elbe .
Preparatory assemblies
During the forced interruption, the two foreshore bridges over the Elbe floodplains, which were very wide at this point, were prepared so far that their steel structures reached right up to the banks of the Elbe, but had not yet reached their final length of 275 m and 214 m respectively.
The supporting structure of the river bridge was installed on the left flood bed parallel to the foreland bridge and approx. 60 m downstream. It consisted of the two bridge arches and the suspended girders of the bridge deck, which protruded several meters from the bridge arches on the land side. The bridge arches, however, still lacked the segments under the bridge deck with which they would be supported in the final state on the abutments in the floor of the floodplain. In the assembled state, the current bridge was therefore designed as a tied arch bridge in order to give it the rigidity required for the floating method. For this purpose, it was also stiffened with a provisional steel frame within its arches at the point where the arches were to be placed on the supporting structure used when moving. In this condition, the bridge element was around 140 meters long and weighed 1,800 tons.
In the river bed, just in front of the banks, scaffolding towers were erected as temporary bridge piers on which the river bridge was to be placed at the end of the shift.
Before the current bridge was installed, a sliding track made of a horizontal framework was set up under its half on the bank side . Lifting scaffolds with strand jacks were erected in the spaces at both ends of the structure of the river bridge . In addition to the river bridge, a carriage with a high support structure and a carriage were provided. The feed carriage consisted of very flat, self-propelled modular transporters from the specialist company Mammoet , on which four groups of two commercially available containers stacked on top of each other were attached, which were supposed to carry the landside part of the river bridge. That is why the feed carriage was also called a container carriage.
Floating method
Lifting the power bridge
First of all, the support structure of the bridge was raised by around 10 m using the strand jacks on the lifting frames. Then the waiting carriage with the support structure was moved under the river-side half of the river bridge onto the sliding track and the feeder carriage ( container wagon) was moved under the girders protruding from the bridge arches on the land side, and finally the current bridge was placed on the support structure and the feed carriage. The wind speed was not allowed to exceed 28 km / h during this process, in order not to endanger the exact setting down. The lifting scaffolding with the strand jacks could then be dismantled and removed.
Advance to the bank
The carriage with the bridge on its supporting structure was then moved to the bank. The landside end of the river bridge was supported by the feed car ( container car ) which was carried along at exactly the same extremely low speed . Teflon plates laid on the sliding track as sliding pads reduced the friction.
As a result of unstable hydro-meteorological conditions and corresponding warnings from the representatives of the Czech dams, swimming in was postponed by 10 days until it could be expected that the water level could be kept within a maximum fluctuation range of 5 cm.
Moving the sledge onto the pontoons
On December 17 and 18, 2010, the water level was so stable that the feed carriage, including the supporting frame and bridge, could be pushed onto two pontoons attached to the bank and fastened there. As before, the feeder car ( container car ) was carried along, but remained on land.
Floating in the river bridge
The actual swim-in followed on December 19, when the water level was allowed to fluctuate by up to 35 cm, but the fluctuation actually did not exceed 2 cm. The pontoons were initially moved by a push boat so far across the current in the direction of the other bank that the carriage that supported the girders protruding on the land side over the bridge arches arrived just before the bank edge.
The feed carriage, which with its numerous, individually controlled and driven wheels, could take a new direction of travel without changing its position, was now given a direction of travel upstream along the bank.
The push boat then moved the two pontoons approx. 60 m upstream to the final position of the river bridge between the approach bridges. In doing so, the distance to the feed carriage traveling at the same speed on the bank had to be kept exactly at all times.
After the pontoons had reached their exact position between the temporary bridge piers, the river bridge was placed on them. Finally, the pontoons with their supporting frame and the feed carriage could be moved away. This ended the swim in the Waldschlößchenbrücke. It lasted a total of 17 days, including the 10-day break due to unstable hydrometeorological conditions.
Web links
- Swim in Waldschlößchenbrücke Dresden , 3D animation of the city of Dresden, which does not quite correspond to the later version, on youtube.com
- Swimming in the power field , time-lapse video of the city of Dresden
- German-Czech cooperation using the example of floating the Waldschlößchenbrücke in Dresden. Workshop of the environmental office of the state capital Dresden with numerous photos (so-called lecture Jakob )
Individual evidence
- ↑ Swim in Waldschlößchenbrücke Dresden , 3D animation of the city of Dresden, which does not quite correspond to the later version, on youtube.com
- ↑ Swimming in the Stromfeld , time-lapse video of the city of Dresden
- ↑ Peter Hilbert: Bridge builders demand 18 million. Article from January 24, 2015 in the Sächsische Zeitung - SZ-Online.de
- ↑ a b German-Czech cooperation using the example of floating in the Waldschlößchenbrücke in Dresden. Workshop of the environmental office of the state capital Dresden with numerous photos (so-called lecture Jakob )
- ↑ Photo of the container car on p. 34 of the above workshop Lecture Jakob .