Next Monday the construction process of the Bridge Pavilion designed by Zaha Hadid for the World Fair 2008 shall begin and it will consist in the moving of the 140m structure, which is currently resting on the right bank of the river, into its final position.
This part of the bridge which has been built in dry conditions on the bank, out of the river itself, weighs 2,200 tonnes and will travel 125m to its final position in 53 days.
It is a façadeless steel structure without its internal concrete deck due to the weight limitations which are to be moved.
More than 20 people shall be involved in the moving operation and during the whole process, 150 welders and assembly operatives worked on the left bank of the river, informed sources from Expo Zaragoza in a press release.
The Bridge Pavilion has three supports, one on each bank and one on a central isle in the middle of the River Ebro and it is the right span, which is further south, which has been constructed in dry conditions on the bank of the river.
At this moment, the provisional supports are being removed upon which the structure was built, which will allow the vertical movement of the aforementioned to begin on Monday.
This movement will allow to check the exact weight and the distribution of the structure which is to be moved and at the same time the total removal of the current supports.
The bridge will remain supported on a series of forward and rear bogies which travel on a track pushed along by hydraulic jacks.
At the rear end of the bridge there are a series of cables which keep it stable and avoid sudden, uncontrolled movements.
Due to the shape of the bridge and its location in relation to surrounding constructions it is necessary to employ three tracks, first the one located further west and the central one and after the central one and the track located further east.
The first movement is 27m in direction towards the river, after which the lower part of the bridge will be covered with sprayed concrete in the areas which are inaccessible from land.
The unit shall be newly weighed so as to check forecasted structural calculations and to adjust the operations to the reality and after which there will be a further movement of 9m parallel to the river, changing the direction of the bogies so as to change the rolling tracks.
Finally, the bogies shall be turned again and the entire structure shall be moved 17m towards the isle, when from which it will be necessary to bring the tower cranes into action.
From the central support, where a double 40m high mast has been erected, a cable shall be launched to the nose placed in the structure, which shall push and shall be gathered up in the belly of the bridge, so pulling it across to the other side of the river.
The bridge shall move in several phases supported on the rear and forward bogies and with the stretched cable over a distance of 54m, after which the forward bogies shall be removed and the structure shall be moved a further 25m with the cable and the rear bogies.
There are also cables to guide the bridge horizontally, which also allow the correction of undesired movements caused by wind or other causes and which are controlled topographically and measure the pressure on the distinct support jacks and the deformation on the face of the support legs on the bogies.
All this information is sent to computers which process the data and allow the maneuver to be controlled.
Once the structure has arrived to its position, the supports shall be removed and the bridge shall be lowered 2.7m until it is joined with the already constructed part on the isle and the left bank.
Once this phase is over, which shall last 53 days, the final parts of the structure shall be continued with, where currently the cable crane is located.
On the right bank, the assembly Works of the façade are to begin, with the corresponding tests on the part which shall be moved in the moments of stopping, the phase in which the bogie supports shall be removed from the bridge as well as the concreting of the external skin to give it its final appearance.
The launching team shall move the bogies to the distinct support areas depending on the needs whilst the bridge is resting on the rest areas.
On the left bank, the works continue regarding the concreting of the deck, fire protection and the service galleries where all the bridge installations shall circulate.