SH1 Auckland Northern Corridor Improvement

The Northern Corridor Improvements (NCI) in located in Auckland’s North Shore and it consists of the SH1 widening from Oteha Valley Road in the north to Constellation Drive in the south and the SH18 widening from the Albany Highway Interchange in the west to the SH1 connection, the extension of the North Shore Busway at the eastern side of SH1 and a new Shared User Path.

Gaia Engineers is the Lead Geotechnical Engineer of the project.  The project comprises the construction of 12 new or upgraded bridges, more than 60 retaining walls with a total length of more than 8km in urban environment adjacent to SH1 and SH18.

The geotechnical design involved the design steel post & concrete panel retaining walls, soldier pile retaining walls with and without anchor tie-backs, concrete L-shape walls, geogrid reinforced slopes with ‘soft’ green facing and the foundation design at the RE MSE walls. The bridge geotechnical design consisted of the pile foundation design including the underpass under SH1. Earthworks design included wick drain ground improvements.

Project challenges were the design in limited urban space adjacent to SH1.

Gaia Engineers provided continuous geotechnical services from the tender in 2017, during the detailed design from 2017 to 2018 and during the construction phase since 2018 through to project completion in 2023.