Coromandel SH25A piles driven in at bridge site

Giant piles have been driven down over 20 metres to support the new viaduct bridge at SH25A's Taparahi site. Image / Waka Kotahi

Waka Kotahi- NZTA has provided an update on their contractor’s progress at the Taparahi State Highway 25A bridge site, which includes the insertion of giant piles.

Damage from Cyclones Hale and Gabrielle aggrandised an earlier 60-metre gap in the road caused by the Auckland Anniversary Weekend flooding to about 110 metres, and the destruction cut off access to the eastern Coromandel Peninsula at the summit of State Highway 25A at Taparahi, around 10km from Kopu south of Thames.

Up to 100 contractors are working over a 20-hour-a-day cycle on the project, aiming to meet a March deadline. The total cost is expected to be around $50 million, at least $10 million more than the $30-40m figure quoted by Waka Kotahi in May this year.

Piles have been driven down to support the bridge 21-24 metres deep into the hillside where they’re secured to solid rock.

A rendering of the engineering required to erect the bridge. Image / Waka Kotahi.

In a release, Waka Kotahi said: “The project team are really throwing everything at this site, which has been made easier by fine days. This week has been productive and below is an update on everything that has taken place to set up the site for the bridge construction.”

• Abutment A: On the Thames side (west), the team completed the installation of the seismic casings which fit around the top four metres of the piles and piling work continues. Concrete was poured into the first pile on Friday, August 25.
• The fan drains are now in place improving drainage of the slip site. Work continues building up the working platform at Pier B for the piling rig and crane by placing and stabilising, in layers, the existing site materials. The piling rig will be established at the site next week.
• Pier C: Proof drilling is completed. This helps to determine the depth the piers need to be driven to reach the solid rock foundation. The team has also started soil nailing, which allows another safe working platform to be built for the piling rig and crane once the piles have been installed at Pier B.
• Abutment D: A safe working area has been prepared in this location, by excavating the slope and installing temporary soil nails. This allows work to start on the abutment structure. The piles have been cropped and completed their integrity testing. Work is now under way on grouting the outside of the piles in preparation for pouring the blinding concrete slab. Blinding concrete provides a clean surface for the structural works to be constructed on.
• At our Kōpū yard, we have been busy fabricating the steel beams that will support the pier headstocks and are constructing the formwork for the abutment and headstock pours. The formwork is a mould for the concrete pours.

Minister for Transport and the Environment David Parker visited the site earlier this month and reaffirmed the project was on track for a March 2024 completion.