European engineers come to Ribadeo to see the complex widening of the Santos Bridge.

05/2008

The widening Works related to the Santos Bridge so that it may accommodate the Cantabrian A-8 Motorway are progressing extremely quickly, despite the high technical complexity which places it amongst the most advanced of its type in Europe. In fact, engineers from all over the continent make regular visits to see in-situ the technical solutions employed by the engineers from Dragados, engineering companies and Public Works which are widening a deck which was not initially designed to bear the weight it will have to eventually withstand.

What basically makes this Project unique is the fact that this is the first time that a viaduct has to be doubled in width with different thicknesses depending on the area.
The personnel in charge of the Project also added that it was necessary to add conditioning factors, such as keeping the viaduct open to traffic at all times – a major problem, and the need to keep the river totally clean to avoid any environmental damage.

Therefore, a ‘mobile carriage’ was expressedly designed, which can now be seen upon the deck. More specifically, the first of the large steel structures which are there now, the one which is closest to Galicia. It was necessary to rehearse with different engineering techniques for the first time together and to try out state-of-the–art materials, overall diverse types of specialized concrete.

The footing reinforcement was another headache as it was necessary to deal with the sea, but from now and in the next few weeks, all the work itself will be able to be seen from the exterior as they are about to begin the actual widening process.

The Works promoter, Ignacio García-Arango, believes it was worth all the effort all they were able to cross the river with a minimum visual and a zero environmental impact.


Sophisticated machinery.

The Works can be tackled due to the expertise of the engineers and workers, but shall be undertaken within the foreseen deadlines thanks to the machinery employed, which is a series of devices which only Dragados and one or two other companies in Spain have. So during the Works we could see a machine which breaks down concrete using high-pressure hot water but thanks to which keeps the reinforcement intact. One of the carriages, which is employed to install the steel framework, is a prototype designed especially for the occasion. The other two, used for rubble and concreting, are more common, but are much larger in size and it was therefore necessary to adapt them to the circumstances.

The pre-tensed cabling was done at height, and in this case mostly by the Company from Ribadeo called Galacuatic. The cranes employed to move these enormous structures were also uncommonly large machines and difficult to find. All this to open a stretch of road,initially, at the end of August.

Pedestrian walkway.
Ignacio García-Arango, one of the Project designers, was the creator of the original bridge and is also a regular visitor to Ribadeo and Tapia. He recognizes that not including pedestrian walkways on the bridge “would have been unforgiveable and a dilemma for the people, so we decided to include pavements at the sides of the motorway, so that people can cross over”.
The pavements will be 1.2m each side and Garcia-Rango explained “at the moment I don’t know if they are going to place a steel barrier or one of those new plastic ones, but it will be done like this”, although he knows it will be forcibly uncomfortable, in the sense that they have to be perfectly isolated from the motorway to avoid any kind of possible accident.

P. Villapol and I. García / El Progreso (Ribadeo).



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