SH25/SH25A Thames-Coromandel

3 March 2023

We're working on a solution

We are focused on getting this highway open as quickly as possible, while prioritising the safety of our crew and the community. There is no short-term fix for SH25A, and a number of options are being explored.

A project team has been established and is focused on developing and assessing the options for the rebuild of SH25A. This includes a Waka Kotahi senior project manager, Beca as our consultants, who will prepare the detailed options assessment report, and the contractor Higgins, who is currently managing the closure and will construct the access tracks for the geotechnical drilling rigs.

Other companies involved include consultancies who will manage the resource consenting and land access outside the road reserve, if it’s needed.

What are the options being considered?

Several options have been identified so far and they fit into three broad categories:

• Retreat north and build a bypass around the top of the site.
• Replace the lost section of road with a bridge.
• Rebuild the supporting ground with retaining walls.

On track to a solution. Work on a temporary track is underway to allow access for the geotechnical drilling rig.

Outlook for the next two weeks

Two critical tasks were ticked off this week - making the site secure by installing barriers at either end of SH25A and getting a 20 tonne excavator and bulldozer to site, so work could start on a temporary track for the geotechnical drilling rig.

Between now and mid-March, a 2.7 metre wide temporary track will be built so the drilling rig can get above the slip area to the potential bypass site, another track formed down to area of the slip where bridge piles would be located and then further down to where a retaining wall and the fill behind would be supported.

The rig will then drill 11 bore holes and excavate test pits to assess the stability of the underlying foundation and surrounding area.

Following the testing on all three sites, the options assessment report already underway can be completed to determine the way forward.

Estimated timing:

Late Feb – mid-March: Build temporary access tracks
Mid-March: Geotechnical investigations on site
Late April: Complete options assessment report and determine best option
May: Confirm option and contractor

Please note these times are an estimate. Weather and many other factors may cause delays.

Meanwhile, other important work is underway, including investigations into construction material availability, bridge and retaining wall options, identifying any known archaeological sites and discussions with the consenting authorities on what other environmental investigations should be undertaken.

Once complete, this path will allow a drilling rig in to gather soil samples by boring down to the depth the potential bypass would be formed at. This will help to determine what option to take when reconnecting this part of the network.

What about the loop and the rest of the Coromandel roads?

We appreciate just how vital it is that access to/from and around the Coromandel is maintained, and the roads are as resilient as possible. We’re working closely with Thames Coromandel District Council and Hauraki District Council on this.

What we've done:

• Assessed how traffic and truck volumes are changing and impacting the roads around the Peninsula.
• Prioritised the clearing of drains and culverts.
• Assessed the safety and capacity of one-lane bridges and critical intersections as they continue to be used as part of the detour.
• Installed variable message signs (VMS) so visitors know which roads are closed and where to go.
• Prioritised vegetation clearance to maintain a clear space for heavy vehicles.

What we’re doing now:

• Monitoring the condition of the road around the Peninsula, especially at locations where it is potentially subsiding, eg between Waihī and Whiritoa, and near Manaia
• Developing a destination signage plan, for both local roads and state highways, to help visitors find the best way to their destination.
• Carefully planning the timing and type of maintenance work such as chip sealing and resurfacing to minimise impacts on road users and adjacent landowners and communities.
• Monitoring travel times around the Peninsula to ensure that any causes of significant delay are identified and quickly acted on.

Keep up-to-date

• Keep an eye on our project webpage
• Check out the frequently asked questions
• Check road and weather conditions on our website: Journey Planner.
• Follow our regional Facebook page - Waikato and the Bay of Plenty: Waka Kotahi NZ Transport Agency Waikato Bop
• For local roads, you can keep an eye on the Thames Coromandel District Council Facebook page or website.