Highway and bridge design, Trøndelag, Norway

The project's objective

Fv. 715 Keiserås - Olsøy is part of the toll route network "Fosenvegene", owned by eight municipalities in Fosen, the Agdenes municipality as well as the Northern and Southern Trøndelag counties. The project's main objective is to improve the quality of the existing Fv. 82/155 road and thereby making it the main connection between Trondheim and the outer parts of Fosen. Once completed, the new road is named Fv. 715. The part between Keiserås and Olsøy is in total 16.5 km long.

The project was divided into two parts. The first leg of the road lies within the Leksvik municipality, between Keiserås and Kråkmo at the boundary between North- and South-Trøndelag, and is approximately 13 km long. The road alignment mostly follows the existing Fv. 82's alignment and this leg of the road contains four bridges and a culvert.

The second leg of the road lies from the boundary between North- and South-Trøndelag to Olsøy, approximately 3.5 km in length. This leg of the road contains two bridges.

The project undertaken by EFLA involved tender design and specifications according to the Norwegian Public Road Authorities' design regulations. This applied to the two new stretches of the Fv. 715 road as well as to a total of four bridges.

The Omundvåg bridge is a 50 m long bridge in three spans. It is a post-tensioned concrete slab bridge with abutments and retaining walls at each end.

The Breilielv bridge has a main span of 19 m and two side spans of 2.5 m each. It is also a post-tensioned concrete slab bridge with abutments and retaining walls at each end.

The Olsøy bridge is a three-span, 38 m long bridge of reinforced concrete.

The Skaudal bridge is a three-span, 90 m long, steel-concrete composite bridge. The design of the interface between the bridge and the riverbanks at either side presented a significant challenge due to formations of "quick-clay" in the ground layers at the site. The "quick-clay" is a highly unstable geological formation. This challenge was met by an innovative solution that uses plastics to soften the transfer of forces to and from the bridge ends.

EFLA's role

• Highway design, 7.5 m wide road, approximately 16.5 km long
• Design of intersections and ramps
• Design of the 50 m long Omundvåg bridge
• Design of the 19 m long Breilielv bridge
• Design of the 38 m long Olsøy bridge
• Design of the 90 m long Skaudal bridge 
  

The project's long term benefits

Improved road network in the Trøndelag region of Central Norway.