Wellington inner city bypass: integrated design of trench section for whole of life performance

The Wellington Inner City Bypass is a lifeline urban arterial road that incorporates a trench structure depressed up to 8 m depth. The integrated design using a combination of a concrete trough with steel props and soil nailed walls provide for resilience in earthquakes, robustness against variable ground conditions, sustainability of the environment and durability in Wellington's maritime environment. The structures were designed to perform in major earthquakes. The economical design was based on a performance based design approach, allowing limited displacement in large earthquakes, rather than a traditional safety factor approach. The solutions adopted also embraced sustainability principles, by reinforcing the existing poor ground (soil nailing), and resisting the large earthquake loads through passive soil resistance on the opposite side and friction on the base (trough structure), rather than build massive retaining walls to support the trench. It also allows groundwater flow below the structure, minimising environmental effects and any settlement effects on the built environment. Whole of life performance was ensured for a 100 year design life, by double corrosion protecting the vulnerable steel nails used for soil nailing, and with details such as plugs through the facing to allow for flushing maintenance of sub-horizontal drainage holes. (a) For the covering entry of this conference, please see IRRD abstract no. E218160.


  • English

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 01143966
  • Record Type: Publication
  • Source Agency: TRL
  • Files: ITRD, ATRI
  • Created Date: Nov 16 2009 12:17PM