I went along to the NZTA open day on the Puhoi-Warkworth section of the “holiday highway” project today. There was a lot of information there, and it was definitely worthwhile making the trip. Most of my opposition to the Puhoi-Wellsford road of national (party) significance so far has been because I think it’s poor value for money and because I’m worried that it will delay essential safety upgrades to the existing state highway one road. But the more I find out about the exact details of the route of the Puhoi-Warkworth section (which is probably the easier section of the two), the more I worry about other aspects: like its environmental effects, like its potential for a cost-blowout, like its geological stability and so forth.
As I noted above, there was a lot of information available and I took along my camera to ensure was able to share some of that. While there was a series of posters with typical propaganda for the project (I noted with interest that the preferred alignment was left off the “landscape architecture” poster), perhaps the most useful thing was simply a giant map of the current preferred alignment – which includes indications of the earthworks required for construction.
The first section, shown below, starts at the current Johnstone’s Hill tunnels: To explain the image above a bit, the existing route is shown in orange (you can see the state highway 1 symbol along it), the proposed motorway is shown as the three thick black lines, while the motorway footprint (I assume the land NZTA will need to acquire to construct the project) is outlined in red. The thin black lines on each side of the proposed motorway show the level of cut and/or fill – in essence the extent of earthworks that will be required. I’ve highlighted in blue the necessary viaduct bridge that would be required – it’s around 200m long to give a sense of scale to the diagram.
Shifting a bit northwards, you can see a bit more clearly in the diagram below the cut and fill that will need to be made to construct the motorway in this area. It seems to be basically running along a ridge (this is shown more clearly in the video). Shifting northwards even further the new motorway starts to move away from the existing road a bit more – to avoid Schedewys Hill I presume.
Once again I’ve shown the viaduct in blue to make it stand out. I think this one is also around 200m long.
As might be obvious in the above map, the level of cut and/or fill in this area starts getting very very extensive – many hundreds of metres across in areas. The maps below zooms in a bit, and I’ve highlighted the extent of cut/fill to make it a bit clearer:There are going to be some pretty massive earthworks to complete this section of the route in particular. With such huge cuts and fills, the landscape is also going to be pretty dramatically altered.
Shifting further north again we come to a particularly interesting part of the project – two massive viaducts pretty much one after the other:You can also see them in the video: From my calculations, each of the two viaducts will need to be around 500 metres long. That’s roughly equivalent to the Waiwera viaduct on the current Northern Gateway Road – which looks like this from below: Two of them in a row. Wow, that’s going to be interesting.
Shifting further north again, we start to get into the area of thinking about Warthworth bypass options. Interestingly, as I was standing there staring at the big map there was a local next to me who was giving the NZTA official very much a piece of his mind why it was essential to just build the Warkworth bypass for now, and to build it as quickly as possible. Of course I couldn’t resist chipping in with “and look how nice and flat the land is compared to the rest of the route” and “if we solve 80% of the problem for 10% of the price, isn’t that a good thing?” Interestingly, the only response the NZTA official had to the Warkworth bypass idea was “but the worry then is we never get around to building the southern part”, to which I wanted to reply “yes, that’s the point” – but I held my tongue!
Looking at the indicative route on a simpler map shows how easily we could link in a Warkworth bypass:
So we basically do build the first section of the road, do a quick link in along Perry Road, with a new roundabout on State Highway 1 and we have a Warkworth bypass. Looking a bit closer, it does feel fairly simple (existing Perry Road is in red, new link route in yellow):
There were plenty of other interesting things I found out through discussions with the various officials there. It would seem that the geological conditions between Warkworth and Wellsford are incredibly challenging, and it may be another year before NZTA can release something similar to this for that section. Furthermore, it would seem that NZTA don’t have much of an idea about whether or not to put in the Puhoi interchange, but they did note building it might be pretty environmentally destructive – and I see their point on that note.
All up, it became obvious to me that focusing on the Warkworth bypass for now is a completely no-brainer. The southern part of this project (between Perry Road and Puhoi) is exceptionally challenging, in terms of the earthworks and viaducts required to achieve a motorway standard road. The environmental effects of the project’s southern part are also pretty massive: in terms of earthworks, landscape modification, visual effects and vegetation clearance. I suspect that NZTA are going to struggle to construct this without blowing most of their budget for the whole Puhoi-Wellsford project: which will leave very little for the even more challenging section to the north.