Quay Street strengthening Quay Street strengthening
Auckland Transport (AT) has completed seismic strengthening below Quay Street between Princes Wharf and Marsden Wharf. This is the first step in revitalising Quay Street.
Project status: Complete - last updated 22 December 2020
Project zone: Central
Project overview
To protect Quay Street and the utility services that run beneath it, seismic strengthening of the 100-year-old seawall is needed between Princes Wharf and Marsden Wharf. Getting these foundations sorted will secure the area for the next 100 years.
The seawall forms the harbour edge of an historic land reclamation, which supports Quay Street and the services contained in the road corridor. The first sections of this reclamation were built between 1879 and 1886 along what is now Quay Street west of Britomart, and also east of Britomart, parallel to Beach Road. Subsequent sections were added after the turn of the 20th Century.
Without the Seawall, significant parts of downtown Auckland would be under water.
Caption: Map of Quay Street strengthening site.
How the work will be done
Strengthening will be completed in four sections between Princes Wharf and Marsden Wharf.
- Princes Wharf to Ferry Basin - Jet grout column (construction complete) All 153 jet grout columns are now in the ground between Princes Wharf and the Ferry Basin.
- Queens Wharf to Marsden Wharf - Palisade piling (construction complete) All 104 palisade piles are now in the ground between Queens and Marsden Wharves.
- Ferry Basin - Incline Anchors (construction complete) All 29 inclined anchor are now complete. Rock armour has been placed with massive blocks of stone installed on the seabed as an extra layer of protection to the new seawall.
- Ferry Building - Incline Anchors (construction complete) All 21 sub-vertical incline anchors have been installed.
A tailored approach – three different methodologies were used:
The Quay Street strengthening process employed three different methodologies in different sections of the Seawall, based on consideration of location, suitability of ground conditions, design requirements and level of disruption.
Palisade wall - A series of piles of varying lengths are inserted into predrilled holes and socketed into the bedrock to form an in-ground wall.
This approach offers the following benefits:
- Minimal disturbance to the current seawall.
- Minimises local disruption.
- Minimises construction time and cost.
Jet grouting - Grout is pumped into pre drilled holes to form columns from bottom to top. The columns are laid in an interlocking fashion to provide strength and stability. Jet grouting is used where there is a high concentration of utility services and the Palisade Wall option would compromise those services.
This approach offers the following benefits:
- Minimise disruption to utility services.
- Minimises local community disruption.
Anchoring existing seawall - A series of incline anchors are drilled through the seawall into the bedrock. The seawall is also bolstered by installation of a series of reinforcing bars along the length of the anchored section. Further protection is provided by placing boulders at the base of the seawall to prevent scouring from the “backwash” of ferries and passenger ship traffic.
Anchoring provides the following benefits:
- Causes less disruption to the operation of the ferry basin.
- Allows a co-ordinated approach with other Downtown programme projects
