Transportation

Eldvatn network arch bridge

A new bridge across Eldvatn, designed by EFLA in collaboration with the Icelandic Road and Coastal Administration, is the first network steel arch-bridge to be built in Iceland. The bridge is 80 meters long, carrying the 8 m wide road over the Skaftá glacial river.

About this Project

Client
Icelandic Road Administration

Timespan
2017-2019

Location
Vestur Skaftafellssýsla, Iceland

Contact

The project's objective

Following very large floods in Skaftá river in the south of Iceland in 2015, a large section of the riverbank that supports the old bridge across Eldvatn washed away. This lead to a major loss of bearing capacity of the bridge and brought the need for a new bridge over the river. As a result of difficult geotechnical conditions and erosion of the riverbanks during frequent flooding in the past, the new bridge is positioned further down the river. A network arch bridge in one span was considered to be a preferable solution.

The new bridge features free-standing steel arches, 12 m tall, with a span of 80 m between abutments, where they form a tie-arch system through a stiff connection with the longitudinal steel girders. The steel girders, carrying a 9 m wide concrete deck, serve as tensile ties for the arches. The bridge deck is suspended from the arches by a network configuration of steel rods. This network configuration leads to an effective distribution of the load effects within the arches, resulting in a highly effective structural system.

Superstructure pushed over the river and into place

The structural steel was fabricated in Poland and then transported to Iceland in Mars 2019 where it was assembled on the south banks of the river, making up the 190-tonne superstructure. It was pushed over the river during a successful 3-day jacking operation. This is the first time a bridge is constructed in this way in Iceland. Afterwards, pre-cast elements were laid between the cross-beams and the remainder of the bridge-deck cast on site.

The nature of the network and structural form enables a relatively slender design of the main bearing elements. This, along with the arches not being interconnected in the transverse direction above deck level, is characteristic for the structure, in which a light appearance and a limited impact on the flat landscape as desired.

The bridge was nominated for the Nordic Bridge Prize in 2020.

Environmental issues

Detailed analysis and design of the steel arches aim to fully utilize the bearing capacity of the steel cross-section in order to lighten the appearance of the superstructure in the landscape.

The arrangement of the bridge arches contributes to an efficient distribution of loads in the structural system and has been shown to be very efficient in terms of material use. The final outcome can there be viewed favourably with respect to environmental aspects and carbon footprint.

EFLA's role

  • Detailed design
  • Preparation of tender documents
  • A follow-up on behalf of The Icelandic Road and Coastal Administration of steel manufacturing and installation
  • Consultancy services during construction

The project's long term benefits

The new bridge improves road and traffic safety and plays a vital role in restoring a much-needed passage over the river adjoining the main Ring Road of Iceland.

Being the first network arch bridge to be built in Iceland, valuable experience has been gained in the design process and the construction phase, contributing to further developments in bridge building in Iceland. 


Reising brúar yfir Eldvötn

brú yfir Eldvötn

brú yfir Eldvötn

brú yfir Eldvötn