The Marieholm Tunnel is a 500-meter long road tunnel under the Göta River in Gothenburg. The tunnel connects Hisingen and the Port of Gothenburg with central Gothenburg, and makes life easier for a large number of travelers every day. The tunnel is a submerged tunnel, the third of its kind in Sweden. It consists of giant concrete elements that are mounted at a depth of ten meters. The size of each concrete element corresponds to a football pitch and weighs 25,000 tonnes.
Efterklang has been Assignmented by the Swedish Transport Administration to conduct measurements of underwater sounds in the Göta River during construction and the tipping of crushed rock from barges during 2018. The aim was to investigate whether underwater noise from construction work affected the salmon that swim up through the river. Measurements were carried out using hydrophones at a distance of 20 and 60 meters respectively from the tunnel segments.
The measurements showed that the work with tipping crushed rock did not adversely affect the salmon. The measured levels met the benchmark set by the County Administrative Board by a good margin and no further noise-reducing measures were deemed necessary.