UNDERWATER EXPEDITION

This article describes three examples of the use of immersed precast tubes in the construction of underwater tunnels. Construction recently began on one of the world's largest immersed tube tunnels, the 3.7km Oresund tunnel which will form part of the fixed link between Denmark and Sweden. Its immersed tunnel section consists of 20 reinforced concrete elements, each 175.2m long and 40m wide, and made of eight 21.9m long segments. The elements are constructed in an unusual way, based on the incremental launch techniques used in bridge construction; this method was chosen for various reasons, including speed of construction. The concrete units will be built in quality-controlled factory conditions. The 1.4km long Western Harbour Crossing in Hong Kong carries a three-lane highway, and consists of 12 33,000t precast concrete units, each 113.5m long, 33.4m wide, and 8.5m high. The units were cast in a purpose-built casting basin. The Ted Williams Tunnel is a 1.2km long four-lane road tunnel under Boston Harbour, built to relieve traffic congestion in central Boston, USA. It was built using steel sections, infilled with concrete walls and inverted. The next stage of the Boston project will be to replace existing elevated roads through central Boston with cut-and-cover tunnels.

Language

  • English

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Filing Info

  • Accession Number: 00729197
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Dec 12 1996 12:00AM