Immersed Tunnels

Worldwide, some one hundred tunnels have been constructed by means of the immersed tube technique, the first of these tunnels being the Detroit River Tunnel between Detroit, Michigan, USA, and Windsor, Ontario, Canada, opened in 1910. Of the existing immersed tunnels, 90% serve road and railway traffic, while the remaining are service tunnels which convey electrical cables, pipelines and the like, or act as water intakes or outflows. Immersed tunnels are normally classified in two main categories, the American type, or, the steel shell type, and the European type, or, the reinforced concrete box type. The Danish contribution to the immersed tunnel industry, as designers and as contractors, has been made in the latter category, where they have been pioneers.