Just before Christmas the NZTA announced they were working on route protection for the Warkworth to Wellsford project with the formal consenting process likely to kick of within the next month or two. The project is the second stage of one of the previous government’s seven Roads of National Significance and the first stage, from Puhoi to Warkworth, is currently carving through hillsides and filling in gullies and is due for completion in late 2021.
This is happening despite the project not being a priority under current government policy and even the NZTA admitting that construction on the project “remains at least 10 years away“. This is also at a time when the NZTA appear to be in disarray and struggling to prioritise funding for a huge number of critical projects urgently need all around the country.
It makes me wonder if they’re trying to build up a backlog of motorways ready to go should we have a change of government within that time frame. But it’s hard to see how the project will ever stack up under a rational analysis. The indicative alignment is about 26km long through some very difficult terrain and includes an 850m long, twin-bore tunnel as well as three full interchanges. The NZTA told me “the updated cost estimate of the new Warkworth to Wellsford alignment will be included in the business case when it’s presented to the NZ Transport Agency Board later this year” but previous estimates have put it over $1 billion. Given the construction cost increases since then the cost could be a lot higher.
That cost might be okay if it was a well-used piece of road but the most recent data publicly available, from 2017, shows traffic volumes just north of Wellsford at just over 11k vehicles per day and between Wellsford and Warkworth at just over 12k per day. There are many state highways with higher volumes, higher growth and easier construction costs that we aren’t talking about turning into motorways. Also as a comparison, the Puhoi to Warkworth section costs less (about $700m), has about twice the vehicle volumes and it only had a BCR that returned 90c to $1 for every $1 it costs. Of course, proponents of the project will note that SH1 is the key link between Auckland and Northland, and a resilient link is important, but resilience can be provided in other ways, like through safety improvements – some of which are currently underway.
What’s of most interest right now though is the current indicative alignment the NZTA are looking to consent.
There have been some changes to parts of the project from what was presented in 2017. These include a revised Warkworth Interchange, a shift in the alignment of the tunnel and new location for where the route connects back into the existing state highway at the northern end.
Consideration has also been given to how the project might be constructed, including how the site is accessed and how large quantities of earthworks are managed. Permanent features of the project like stormwater treatment ponds and areas for landscape and vegetation planting have also been considered.
All of this has resulted in the proposed designation boundary shown on the map. Final refinements are now being made to the proposed designation boundary, taking into account feedback from ongoing landowner engagement.
There’s a much more detailed version of the indicative alignment here and it also shows where there are likely to be some of the large cuts and fill sections.
One of the aspects of the design that really stood out to me was the sheer size of the Warkworth interchange that is now planned. The previous version showed the motorway just veering off but now the NZTA have changed this to a full motorway to motorway interchange, perhaps reflective of the fact they’re building connection to Warkworth to motorway standard.
The proposed interchange is so massive and you can nearly fit all of Warkworth within it’s footprint. Below I’ve matched things to scale as much as possible and rotated it around a bit but you can see the result. It’s worth noting that as of the most recent numbers from Stats NZ, the urban area of Warkworth has nearly 5,000 people living int it.
By comparison, the NZTA in their early artistic impression present it as a motorway in the middle of a forest.
As mentioned, we’re bound to hear more about this project in the coming months as the NZTA move towards lodging consent.