Warkworth and the Cost of Sprawl

At the Auckland Transport board meeting today a series of papers really highlight the cost of sprawl.

For the last few years, the Supporting Growth work has been looking at designing the strategic transport networks for future greenfield areas in the South, Northwest, North (around Dairy flat) and in Warkworth. There have been multiple consultations for each of these areas as they’ve worked through the various business case processes.

The papers relate to the plans for Warkworth, which was consulted on last year and where they’ve now completed the Detailed Business Case and come up with a recommended network. They’re now seeking endorsement of the business case and approval of funding to start the route protection process. AT want to protect all of the future routes now before land get subdivided, which would see the cost per m² increase significantly.

The preferred strategic network for Warkworth is below and is expected to cost over $1 billion all up and on top of existing planned projects, such as the Puhoi to Warkworth motorway and Matakana Link Rd, both of which are due to open soon. The projects include:

AT projects – $1 Billion

• Four new arterial corridors
• Northern and Southern Public Transport interchanges
• Northern Park and Ride facility
• Active mode facilities on all corridors
• Active mode and urbanisation upgrades of five existing corridors

Waka Kotahi – $83 Million

• New southern interchange on Ara Tūhono (Puhoi to Warkworth) to provide direct access to heavy industrial land

A breakdown of the costs for each component confirms that most of the costs are in the development of the new arterial roads.

The images below show how the strategic network has, unsurprisingly, not really changed all that much over the various stages of the process and also just how long this has been going on for. In many ways, this highlights some of the problem with the business case industrial complex we’ve developed.

The 11 AT projects include $122 million for property purchases, but as not all will need to be brought straight away, with inflation that cost is expected to eventually increase to $200 million. Of that, AT expect they will need to spend $38 million between now and 2031 which “is based on property acquisitions needed for early delivery and estimated hardship requests“. If they don’t do route protection now, they say it will potentially cost an additional $500 million to do it later and require impacting on 1,000 land owners instead of 160 if they do it now.

Given these costs, it will be interesting to see how the board responds given how eager they were to not make a decision about Great North Rd, which will support thousands of existing and future residents along the corridor.

All of this work in Warkworth is for an expected 17,100 additional people, a four-fold increase on the current population, living in 8,200 new houses. There are also expected to be about 4,600 new jobs in the area.

Route protecting before costs dramatically escalate sounds sensible but what really stands out though is when you consider the cost off all this infrastructure compared to just how many extra houses we might get. On average this will cost tax and ratepayers about $130,000 per household added – assuming all happen. And this is before the cost of adding local roads, three waters and other physical and social infrastructure to support these new residents. This is important because there are often claims that low rural land prices are proof of why we should focus much more on greenfield development.

That high cost results in a benefit to cost ratio of just 0.6 – though they try to claim there are a heap of un-monetised benefits from turning farmland into suburbs.

The costs can be further split out by those new households in the South West, where the bulk of the new housing will be, and in the North East. While they don’t recommend it, they do give the option of dropping the two North East corridors to save money.

Assuming it’s not a typo, some serious questions surely need to be asked about the Riverhead and Kumeu/Huapai networks if they’re going to cost $340,000 per household.

I also wonder what kind of networks we could get within our existing urban area if we were spending those kinds of cost per household figure.

Finally, they claim that with this network it will result in a 9 per cent reduction in Vehicle Kilometres Travelled (VKTs) in 2048 and an emissions reduction of 1,296 tonnes per year over 60 years compared to a baseline network. But in reality, total VKT and emissions will increase because of all the new people and businesses in the area. What would be a more useful comparison is what the VKT and emissions reduction outcome would be if that growth happened within the existing urban area instead.

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