Matt’s post last month on a new apartment development in Albany caused me to start thinking about street grids. As Matt noted, the development will start filling in the big gaps between Albany’s broad, curving roads to nowhere. Here’s a picture of the development:
Albany’s got many attractive aspects. It’s got loads of space for growth, which in a growing city means that it will grow. It’s got aspirations to be a live-work-shop kind of centre, rather than just a mall in a paddock. And it’s close to the Albany Busway station – although the busway hasn’t made it far enough north yet due to some bad decisions by the Government. But that street network could easily cripple it. Albany’s curvy roads and over-sized roundabouts are good for drivers but highly inefficient for people on foot, bike, or bus.
As Jarrett Walker is fond of saying, you can’t argue with the facts of geometry. Roads that meander and don’t connect with each other will always be costly to serve with public transport and difficult for people to navigate on foot.
If sprawled-out exurbs remained on the car-dependent city fringe in perpetuity, it might be fine to build them with inefficient, non-connective street patterns. But if a century of urban expansion has taught us anything, it’s that today’s fringe suburbs will be part of tomorrow’s urban fabric. Over time, they will become more densely populated and require a greater range of transport choices. We will have to think about incorporating them into public transport networks and putting a sidewalk on every block.
Street networks are incredibly persistent. Some European cities are still laid out on right-of-ways first established by the Romans. Or think of Karangahape Road, which has been used as a thoroughfare since Auckland was first settled around 800-1000 years ago. But in recent years, some people have started to think about how we might rebuild or “retrofit” inefficient suburban street networks.
One such effort, Galiena Tachieva’s Sprawl Repair Manual, summarises a number of strategies for retrofitting suburban developments into urban places. Here’s one of her schematic designs for transforming a single-house subdivision, complete with cul-de-sacs, into a neighbourhood centre:
Unfortunately, retrofitting is costly, as it will require governments or transport agencies to buy and demolish houses in order to restore a street grid. As the overall density and efficiency of the neighbourhood would increase following such a rebuild, doing this might even make the government money in the long term. But it would involve some pretty serious up-front expenditures.
In order to quantify the “unfunded liability” associated with inefficient, car-based suburbs, I’ve gone back to Tachieva’s example and put a red X on the properties that we’d have to demolish in order to restore a sensible urban street grid that would enable better PT, walking and cycling provision.
Out of a total of around 180 properties, we’d have to buy and bowl at least 18 to retrofit a proper street grid. That’s 10% of the suburb’s houses that we would have to demolish!
In short, the costs of retrofitting inefficient suburban street networks are so high as to be prohibitive. This raises two questions.
First, what’s going to happen to Auckland’s existing sprawl suburbs? Will they hold their value if it’s not possible to provide them with better transport choices? And if we can’t, will they suffer a reversal of fortune, offering few opportunities for low-income residents cut off at the end of cul-de-sacs?
Second, why on earth are we still building subdivisions with dysfunctional street networks? What form of mad inertia is leading us to construct places like Flat Bush and Massey (below), where road geometry means that it will always be difficult to run a frequent bus route or give people direct walking access to the shops?
Traffic engineers and subdivision master-planners seem to be quite good at “future proofing” their roads for growth in demand. They build them too wide in anticipation of the day when more cars will be driving on them.
But that’s not sufficient. They need to go a step further and future proof against a change in transport demands and a change in the functioning of suburbs. The places that are being built on the edge of the city today will not work very well when they begin to merge into the urban fabric tomorrow.
Remember, you can’t argue with geometry!