Award: City of Oulu, FI
Length: approx. 210,00 m, longest span approx. 40,00 m
Width: 4,50 - 6,50 m
Construction: Wooden arch bridge with glulam deck and natural stone decking
Our services: Design, static preliminary design, cost estimate
The City of Oulu held a competition in February 2021 to design a bridge for the new Hartaanselänranta area, one of the youngest neighbourhoods in the growing city, where preparations for the 2025 Housing Fair are underway. The new residential area is crossed by the mouth of the Toppilansalmi River, which the design competition proposals cross.
For the design competition, Sitowise assembled its own team of experts: "Natural materials fit the spirit of the area and the design goals. That is why we wanted to design the bridge as a wooden structure, as there are no similar bridges in Finland. To bring in new ideas and up-to-date know-how for wooden bridge solutions, we invited a German timber construction pioneer to join us. IB-Miebach was an important part of our team," says Ari Savolainen from Sitowise.
Sitowise participated with two timber construction designs - a block girder bridge and an arch bridge - of which the present proposal, the "Mainingit" arch bridge, was awarded an honourable mention in November 2021 for its bold and innovative use of timber materials.
The structure's supporting framework consists of three different elements, divided into two tied arches connected by a curved connecting element, which is a suspension girder that connects the beams in a flowing arc. The arches and the suspension are made of glulam GL28h, as is the timber plate that supports the deck, connects the arches and forms the horizontal bracing. The use of such solid, glued laminated timber structures has been implemented in an unusual and innovative way that has not been applied to any other known bridge in Finland. The wooden parts are structurally protected from the weather by the watertight natural stone deck, the overhang and sheet metal cladding. All other structural parts such as hangers, cross beams as well as the horizontal bracing of the arches, which cannot be structurally protected, are made of steel.
The wooden bridge is a natural and calm ensemble that integrates the bridge structure into the surroundings and the urban fabric, also in terms of the use of materials. The wooden arches of the bridge stand out discreetly against the urban skyline of Hartaanranta and do not tower above the surrounding buildings. In the middle of the bridge, in the valley of the arches, there is a viewing platform that has been lowered from the main road and offers a stopping point, a place to sit and a good view of the shore.