The Tveit bridge (Tveit bru) on the E16, Norway

This bridge was made of timber structures and paved with asphalt. It has two lanes and is located on European highway E16, which links Oslo and Bergen. The new bridge replaces a narrower concrete bridge built in 1946, which was a bottleneck and led to frequent traffic jams. 

Our services:
  • Location
    Across the Storane river near Ryfoss, Norway
  • Year of construction
  • Dimensions
    Length 40 m, width 9.5 m
  • Client
    The Norwegian Public Roads Administration
  • Built by
    Dokka Entreprenør AS, Eiqon Anlegg AS

The role of ZAZA TIMBER Engineering in this project was to develop technical drawings for manufacture.

In accordance with the construction plan, we developed a 3D model in order to create work files for the CNC equipment. We also developed drawings for assembling the steel parts, which were embedded into the structures in the factory, thus reducing the assembly workload at the construction site.

ZAZA TIMBER Production (previously: IKTK) manufactured and treated the bridge’s 40 m-long and 9.5 m-wide timber structures. We embedded the steel details into the wooden structures, applied pressure treatment using the latest-generation creosote, provided transportation to Norway, and completed the customs paperwork.

We manufactured all the wooden details needed for the bridge structures. For the trusses, we prepared details glued in blocks: the top and bottom cord, as well as the diagonals. The cords were produced with a camber. For the bridge deck, we manufactured deck beams, drip inducers and other details.

The structures are made of pine and spruce with strength classes of GL30c and GL30h. The total volume of the structures is 252 m3, the number of details made was 211, and the longest piece was 27 m.

Cutting, drilling and sawing was done in the factory using CNC equipment. Where possible, we embedded the steel details needed for assembly into the wood, reducing workload at the construction site and speeding up construction.

The bridge takes into consideration the sharply changing and harsh weather conditions, meaning that the details were treated before gluing to protect from moisture and external forces. After gluing and affixing the metal details, the structures were treated in an autoclave with the latest-generation creosote. The new bridge should last for 100 years.

We transported the parts to Norway on six lorries.

Manufacture took four months.

The challenge of this project, considering the huge length and cross-section of the parts, was ensuring high-precision finishes (drilling, sawing) for fastening the steel connectors. The length of the parts also meant we had to find new partners for pressure treating the longer parts.