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POYNDER AVE & GARDEN ROAD BRIDGE REPLACEMENT 

DURATION 

Mar 2024 – Current

CLIENT

Christchurch City Council 

CONSULTANT/DESIGNER

WSP

VALUE

$1,689,000.00

Hunter Civil have been engaged by Christchurch City Council to complete the replacement of two bridges at the end of their design life located in Merivale that span the Wairarapa Stream, on Poynder and Garden Road. The bridges are being completed one after the other to minimise the impact of detour routes for residents and local road users.

The Poynder Ave replacement is currently well underway. Prior to the demolition work, existing utility services running through the existing bridge and overhead powerlines have been temporarily diverted to allow for work to be safely undertaken. Due to the work being located within the stream, a key focus for the team is keeping the live stream separate from the work area to protect the stream environment. A line of sheet piles tied into the bank parallel with each abutment has been installed to isolate the work area from the stream. To minimise the amount of construction debris entering the waterway while dismantling the existing timber structure, a temporary debris catchment was set up under the bridge deck to catch any debris that may have fallen into the stream. The existing concrete abutments have been removed and the area excavated and prepared for the installation of piles. 6 steel piles have been driven into the ground along each abutment to a depth of approx. 10m below ground level using both a mobile and telescopic crawler crane mounted with a pile driving hammer.

Whilst the site works got underway, we’ve had separate teams working offsite, building the precast wing walls and pre-stressed deck panels. The abutments are constructed using a combination of precast panels and insitu concrete to tie the piles into the abutments which expedites site works and forms a solid platform to install the new deck panels. Following the completion of the abutments and rock scour protection, the sheet piles will be removed to then allow the prestressed decking units to be installed.

Finishing works include shaping and completing rock armouring along the riverbank, landscaping, installation of kerbs, footpath and road reinstatement. A similar methodology will be used for the Garden Rd bridge replacement, which is currently expected to begin late July once the Poynder Ave bridge has been completed and open to traffic.

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