Basagoiti Viaduct, Spain

Construction of the Basagoiti viaduct, Spain

Facts and figures

  • The Basagoiti Viaduct is located near the town of Mondragón in Guipúzcoa, the smallest Spanish province in the Basque region of Northern Spain
  • A total of 1,800 tonnes of equipment was hired

Constructed as a key link on the Arrasate to Eskoriatza section of the new Vitoria to Eibar motorway, located in Spain, the 391-metre Basagoiti Viaduct has been formed using heavy duty 1000 kN Megashor shoring equipment from Interserve’s formwork and falsework specialist business, RMD Kwikform Ibérica.

Designed by a specialist team of six engineers, the formwork and falsework solution for the construction of the viaduct involved the hire of a total of 1,800 tonnes of equipment, including a combination of our world leading Megashor 1,000 kN heavy duty steel shoring, Superslim soldiers, R700 girders, Kwikstage shoring and T200 timber beams.

Due to the complexity and length of the viaduct, our engineering team has worked throughout the three phases of construction to support the erection teams on site. In order to overcome some of the technical challenges, the engineering team developed new special pyramid shaped header parts and adjustable Superslim beams, that were manufactured specifically for the project.

These additional parts enabled us to design a unique system that allowed two key parts of the formwork, the Megashor beams and R700 Girders, to be connected together safely and swiftly, at the required angles for the support structure to allow the viaduct to be cast in-situ.

Achievements

Dealing with difficult terrain - Having worked on a number of bridge and viaduct projects with similar terrain issues, we opted for a tried and tested support structure, using R700 steel girders supported by Megashor towers, positioned on concrete blocks at dedicated intervals. Due to the added weight pressures exerted by the solid ‘arms’ and self compacting concrete, this shoring support system was further strengthened by reinforcing the girders, using additional Megashor beams.

Combating the effects of concrete - Using a combination of R700 girders and additional formwork, we were able to design two block structures, which were placed on each side of the pyramid shaped header to support it whilst concrete was poured. Once the concrete was poured these blocks could then be removed, leaving the header to support the concreted arm. The blocks were then re-used for the same process on each of the three piers. The final technical challenge was the variable thickness of the decking design. This was overcome by redesigning our fixed steel beam Superslim soldier into an adjustable telescopic product. This made the erection of the deck support formwork much simpler, lighter and faster, allowing the project to be kept on schedule for a 2009 opening.