Every weekend we dig into the archives. This post by Peter was first published in June 2015.

Earlier this month, urban policy researcher Todd Litman published a useful summary of some of his new research into the cost of sprawl:

Our analysis indicates that by increasing the distances between homes, businesses, services and jobs, sprawl raises the cost of providing infrastructure and public services by 10-40 percent. Using real world data about these costs, we calculate that the most sprawled quintile cities spend on average $750 annually per capita on public infrastructure, 50 percent more than the $500 in the smartest growth quintile cities. Similarly, sprawl typically increases per capita automobile ownership and use by 20-50 percent, and reduces walking, cycling and public transit use by 40-80 percent, compared with smart growth communities. The increased automobile travel increases direct transportation costs to users, such as vehicle and fuel expenditures, and external costs, such as the costs of building and maintaining roads and parking facilities, congestion, accident risk and pollution emissions.


We estimate that in total, sprawl costs the American economy more than $1 trillion annually, or more than $3,000 per capita, and that Americans living in sprawled communities directly bear $625 billion in extra costs, and impose more than $400 billion in additional external costs. This is economically inefficient and unfair: it wastes valuable resources and imposes costs on people who do not benefit from sprawl.

These findings should not be particularly surprising to regular readers of Transportblog – or, indeed, to anyone with an elementary understanding of geometry. (Serving dispersed suburbs with network infrastructure is more expensive.) But the magnitude of the costs is impressive.

I was particularly struck by the following chart, which illustrates the amount of space required for various different transport modes. Litman estimates that each automobile requires a total of 80 to 240 square metres, mostly for parking. By comparison, walking, cycling, and public transport require less than 20 square metres per passenger:


As I’ve written before, space is expensive in cities, which means that we must use it efficiently. Moreover, the cost of space for cars is rising rapidly, while demand for driving is levelling off. In this situation, devoting more space to roads and parking – or preventing the re-use of road space and parking lots for other purposes – may represent a significant misallocation of resources:

AHB traffic volumes and real house prices, 1961-2014

So, we might ask: How much space have we misallocated as a result of our bias towards building roads rather than public transport and cycling options? And what else could we be doing with this space instead?

First, some data. As we tend to build road networks for peak demands, they tend to have spare capacity during the middle of the day and evenings. Consequently, I’m going to focus on trips taken in the morning peak. This is a conservative view on the space required for a car-based transport system, as cars used during off-peak times still require lots of parking.

According to modelling results reported by Wallis and Lupton (2013), in 2006 there were around 450,000 vehicle trips taken during the morning peak. (See Table 4.1 in their report.) Most of these are trips in single-occupant vehicles. How much space do we need to accommodate all these vehicles?

Based on Litman’s figures, travelling by car requires an average of 150 square metres of space – around 40 square metres of roads per car when moving and 110 square metres for parking. This implies that the 450,000 vehicles moving around during the morning peak occupy 67.5 square kilometres of space, including (at minimum) 18 square kilometres of roads.

That’s a lot of land. Urban Auckland covers a total area of around 544 square kilometres, which suggests that we’re using up around 12.4% of the city’s land area simply to move single-occupant vehicles during the morning peak and warehouse them during the day.

If anything, this is probably an under-estimate of the spatial cost of Auckland’s car-based transport system. A 2013 UN-Habitat report on streets as public spaces and drivers of urban prosperity found that Auckland devotes 14% of its land area to roads alone. Parking is likely to cost us even more space, as this map of Manukau central shows. Everything that’s not coloured in red or green is a carpark or a road:


But regardless of whether we’re dealing with 12% of the city’s land area or 30%, we’re talking about a lot of expensive space devoted to moving or storing cars. Even a modest reduction in the share of people travelling by car in the morning peak would save us a large amount of land.

Let’s say, for example, that we’d invested in better transport choices that enabled 10% of the people in cars to shift to public transport or cycling, which require around 10 square metres of space per person. If we had done so, we would have had an extra 6.3 square kilometres of land that didn’t need to be used for roads and carparks. [6.3km2=45,000 vehicles*(150m2-10m2)]

This is valuable land. Assuming an average land price of around $500 per square metre, it’s worth $3.2 billion. And it could be used for so many more things – housing, businesses, public parks, schools, etc – if it hadn’t been gobbled up by our space-hungry transport system. If it had been developed to the same density as Auckland’s average neighbourhood – around 43 residents per hectare – instead, it could have housed 27,000 people.

In a city that’s struggling to find enough space to house it’s growing population, this amounts to a minor scandal. Since the 1950s, local and central governments have spent lavishly on roads and neglected public transport, walking, and cycling. Those decisions have inadvertently contributed to our housing woes today, as they’ve saddled us with a space-inefficient transport system and a shortage of developable land.

At the moment, local and central governments are looking at ways to get best us out of their own properties. Auckland Council’s setting up Development Auckland to manage and develop its substantial land-ownings. At this year’s Budget, the Government announced a more hastily-developed plan to sell off a significant chunk of the land that it owns in Auckland for development.

Given their interest in the subject, they should also be thinking hard about how to minimise the “opportunity cost” of Auckland’s space-hungry car-based transport system. Investing in public transport and safe walking and cycling can allow us to move more people without gobbling up more valuable land.

What do you think about the spatial cost of our car-based transport system?

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  1. The mentally that we must have wide roads and street parkings in order to maintain the life style that we currently have (by that I mean overly reliance on getting around in a car) need to change in Auckland.

    Working the in industry as a civil engineer, we get backlashes from the community on streetscape improvement project almost every time because street parking have to be removed for improvement of other amenities (wider footpath or better planting or adding bus lanes). Because of this disagreement from the community, we have to redesign and re consult, and this can happen at least 2 to 3 times during design. It is time consuming and costly for the local government, which at the end of the day are costs on rate payers.

    1. Yes, it’s a problem. And the situation has been recognised by the experts. The change required is noted consistently throughout policy, in all the various AC and AT plans. Unfortunately:

      1/ No-one promotes it in education so that people can digest the ideas before it arrives in the form of a project in their own neighbourhood. This is a failure of Council and AT engagement. They’re not proactive, and that’s because they’ve been weak, wanting to hide behind others.

      2/ AT look for the ways to avoid the policy. So if you take AT’s Parking Strategy, for example, and read it as a whole, it’s very clear that the direction is that public transport and active modes need to be prioritised, that parking is a poor use of land, and that traffic volumes can be managed by reducing parking supply. But one or two ambiguous words mean that AT’s own civil engineers interpret it to mean that they can’t remove parking without mitigating. Which is just false.

  2. I’d say Botany (in the above photo) is perfectly future-proofed, especially the mall. It has a central lane you could concievably run street level mass transit down, and the car parks will provide space for big box/residential additions and future expansions as motor vehicle use declines.

    Yes, at the moment it’s a giant sprawl of empty space, but connecting these places as nodes and then intensitifying the absolute shit out of them as mixed use developments is the way forward.

    1. The problem is that if we try to wait for society to peacefully get every driver on board with the idea before these future improvement ideas take hold, we’ll never see improvements.

      Shall we start with Botany now, do you think? Rezone so land owners are required to convert some large portion of the carpark land area to a better land use within 7 years, or a penalty is due. That would get focus away from greenfields development all of a sudden, I imagine. And might have the local population demanding sustainable transport options on their streets, otherwise they won’t have access to the malls… And if that sort of zoning change was happening, there’d be very little tolerance amongst the public for Council approving or building another carpark.

      1. Good plan. We could screw things up for people so badly and make your way the only option and eventually people might all fall into line and comply. If tax penalties don’t work we could move on to public beatings and maybe special camps. Or perhaps people who live and shop at Botany do so because they like it. Maybe they like have parking and maybe they like being able to drive places.

        1. Haha well called out Miffy. When democracy doesn’t satisfy the few that know better then the big stick solution of threats and fines will definitely work, at least in the ‘know betters’ myopic world.

        2. I think you’re both wrong. The problem is that driving is way too subsided by the government and council. Do people like being subsidised – definitely. But the outcomes are always bad. We don’t need taxes and rules or even public beatings; but people should have to pay the real cost of that 150m2 of land they use.

        3. Exactly Jimbo. Imagine if we gave away 150sqm free for people to build houses on. People would love that too. But there might be some unintended consequences…

      2. I’d rezone land so that it *can* be developed for that sort of thing, but only that. You might find malls are prepared to sell down parking space for residential development if things get slower and they can rationalise land use.

        I’m not sure I’d take the stick approach. A firm commitment and well-articulated/visualised plan for regional light rail, special provisions for people to develop dense residential using express consents and then just see what happens. Would you buy a 140sqm apartment above Syvlia Park? I know I’d consider it if it cost the same was what some people are asking for a 2 bedroom apartment in town. How do we work towards making that possible?

  3. Very interesting post, thanks. I had a look at the last link. Has anyone tracked what’s happened to those 430 hectares of of publicly owned land in Auckland that the 2015 Government wanted to sell for development?

  4. The cross subsidisation needs to stop. Free parking needs to be unbundled from the price of retail so those that choose to catch a bus cycle or walk to a mall aren’t paying for everybody else’s parking in their retail spend.

    1. Good luck getting retailers to turn over enough to pay mall rents if you’re going to stop everyone who drives a car from being able to shop there.

      1. Who said anything about stopping people driving there? I think Mason’s idea is that people who don’t drive and park to these places shouldn’t pay as much as those who do. Answer – issue tickets for parkers at entry-gates where your number-plates is also read. You pay your parking charge along with your purchases, and if you don’t pay you wind up with a fine. Treat it like fare-dodging.
        If all large retail carparks are obliged to have this then the option to shop elsewhere (where motorists can continue to freeload) no longer avails.

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