11.09.2012, 10:00 Uhr

1st Prize in Nya Skurubron Design Competition

On Wednesday 5 September 2012, Trafikverket Stockholm announced that the JV of Dissing+Weitling, Danmark, Leonhardt, Andrä und Partner GmbH, Germany, and ELU Konsult, Sweden is the winner of the international contest to design a new bridge across Skuru Sound. Our JV submitted a simple yet technically advanced design proposal for the new bridge which will solve an untenable traffic situation for people commuting to Stockholm, a figure exceeding 52,000 every day.

The new bridge will share the Sound with the existing Skuru Bridge which is a copy of the original arch bridge from 1914. At that time, it was the largest concrete bridge in Northern Europe. The original bridge has major cultural, historical and architectural value, and it has gained iconic status among bridge experts around the world. At the same time, this strong, almost monumental structure co-exists in glorious harmony with the steep, rocky slopes, the tall trees and tiny houses of the Archipelago. This is the context in which our team decided to develop a design with a very simple and transparent visual expression.

Therefore, a design without towers, cables or viewing platforms was chosen. The bridge has a structural lightness with a slender, aerodynamic deck in steel, and it is made as transparent as possible by, for example, aligning the piers of the new bridge with those of the existing bridge. This creates a connection between the two structures, and the new bridge will not block the view of the old.

The 6-span continuous girder bridge is supported by 5 Piers and 2 Abutments at the end. Bearings are only provided at the abutments, while the piers are restraint into the superstructure. The spans are 56 m - 68 m - 68 m - 68 m - 62 m - 48 m = 370m.

The deck consists of two closed, streamline shaped, steel box with a 150 mm thick concrete slab on top. The piers are y shaped, the upper v has the same geometry for all piers, while the solid con-crete shaft varies in length. The v-part is made of steel and transfers loads directly into the steel superstructure. To reduce temperature loads, concrete hinges are provided at the base of the shorter piers.

This kind of deck layout has a number of advantages, e.g.

  • no additional bracing is needed during erection, its stable in rigid
  • wind loads during erection are small (streamlined body)
  • no additional formwork is required for casting of the deck , if done after placement of steel segments ( which is most likely the case whatever erection scheme is selected)
  • protects concrete from drying out in case de-humification is used as a corrosion protection measure inside the box structure
  • allows a simple exchange of the concrete slab, segment by segment. If portion of the slab are taken out, the remaining area is still continuous for all forces (shear, bending and torsion)
  • Concrete provides better riding surface than steel, also in wintertime

In summary, it combines advantages of orthotropic decks and composite deck. It has all the structural advantages of an orthotropic deck, but it’s better in wintertime (icing) and needs less steel:

  • only 10mm plate thickness instead 12 to 14 mm, as Eorocode requires
  • distance of stiffening plates is 600 mm instead 300 mm.

As traffic has increased dramatically during the half-century Trafikverket Stockholm has therefore decided on an efficient process for the new bridge, starting construction in 2013 and completing the new bridge in only three years.