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Intersections and Corners, Exploring Auckland’s Urban Structure

A heart is not a disembodied thing that you set down arbitrarily like choosing a shopping centre site. It has to have an anatomy that runs into the neighbourhood. – Jane Jacobs via Future Cape Town

W392

Looking north west from the vicinity of Jervois Road, showing the Ponsonby Post Office on corner of Saint Mary’s Bay Road and College Hill (Sir George Grey Special Collections, Auckland Libraries, 1-W392)

Increasingly network theory is being explored as a way to understand urban morphology. Measuring features such as intersection density or block size has been found to be highly correlated to walkability and potential to support transit. Portland Metro and the Transportation Research Board use intersection density as one measurement of the viability of transit oriented development (TOD), and Walk Score uses it as a factor in its “Street Smarts” version.

It doesn’t take computers to understand spatial theory. Jane Jacobs devoted an entire chapter of Death and Life to it- “The need for small blocks” in which she asserted that block size was central to movement choice, shop diversity, convenience and thus urban vitality. More recently, Bill Hillier at UCL through his research department and book called Space is the Machine identifies spatial integration – the heirarchical relationship between streets in a network as the key driver of urban outcomes. This relationship between street structure leads to a  “movement economy” where urban activities respond to take advantage of what is in a way elliptical, the same urban advantage of access, proximity and convenience.

Such locations will therefore tend to have higher densities of development to take advantage of this, and higher densities will in turn have a multiplier effect. This will in turn attract new buildings and uses, to take advantage of the multiplier effect. It is this positive feedback loop built on a foundation of the relation between the grid structure and movement this gives rise to the urban buzz, which we prefer to be romantic or mystical about, but which arises from the co-incidence in certain locations of large numbers of different activities involving people going about their business in different ways. -Space is the Machine

In an earlier post I identified the existing real estate premium of well-located, fine grain urbanism in the city centre. The highest value property has the advantage of a being from an era where access and proximity was not an option but the fundamental essence of urbanism. In this exercise I continue to explore local urban structure using a GIS tool called the Urban Network Analysis Toolbar.  This exercise is a way to test the local relationships between neighbourhood structure and on-the-ground conditions.

Below is a look at the Point Chevalier, Grey Lynn, and Ponsonby neighbourhoods. (Un)fortunately, this neighbourhood provides a good test case since it has been divided up un-naturally into an archipelago by the motorway system. The maps calculates “Reach” which determines how many places (dots) each house can reach within 1000 meters using the street network.  The red dots represents high levels of reach and the green dots represent low levels.

Calculating reach for one of Auckland's central suburbs.

Calculating reach for one of Auckland’s central suburbs.

Not surprisingly, much of Ponsonby Road has the highest levels of proximity due to its neighbourhood structure: short blocks, density, and streetcar genesis. In later posts I’ll return to Ponsonby Road but for now I would like to examine a few of the other places that jump out.

One cluster standing out in a field of moderate scores is the intersection of Richmond Road and Warnock Street in West Lynn. Here there is a concentration of intersections creating a condition of convergence. This is what it looks like on the ground – a seemingly successful place with local-serving stores like a grocery store and a butchery and more boutiquey ones like Nature Baby that serve a wider retail catchment.

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West Lynn shops.

Another cluster is located at a complicated Y-intersection of Lincoln, Richmond, and John Streets. Here is what it looks like on the ground. Again, there is a local collection of neighbourhood-serving shops and some specialty stores (like a niche bookstore) and restaurants.

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Richmond Road shops

Returning to Jane Jacobs, here is what she says (via hearthhealth.wordpress.com) about corners which are increased by the condition of short blocks and the benfactors of a connected neighbourhood structure.

Let’s think a minute about the natural community anatomy of community hearths.  Wherever they develop spontaneously, they are almost invariably consequences of two or more intersecting streets well used by pedestrians.  On the most meagre level, … we have the cliché of the corner store or the corner pub that is recognized as a local hangout.  In this cliche, corner is the significant adjective.  “Corner” implies two streets intersecting in the shape of an X or a Y.  In traditional towns, the spot recognized as the centre of things surprisingly often contains a triangular piece of ground.  This is because it is where three main routes converge in the shape of a Y.

Finally, for comparison, here is a very low-scoring site that retains a historic building that seems comparable to many places along Ponsonby Road and in the busy local centres documented above.

archhill

Great North Road

Why are these places so different today? What has happened to Great North Road that makes it so low scoring in this analysis and so seemingly low value on the ground? What relevance does this sort of analysis have on spatial planning, the potential to leverage the advantanges of urbanism, or the trade-offs between designing streets for local vs long-distance movement patterns?

Grids Gone Wild, Episode 1

Continuing on from my recent post on our troublesome speed limits, I wanted to further document some of the other problems I see on local streets. I have a particular fondness for our streetcar neighbourhoods with their old homes and regular gridded street network. In an earlier post I calculated the advantages of the streetcar grid to typical suburban development patterns. The reticulated grid forms a highly efficient transportation structure as well as a convenient method for land development. In addition to being highly walkable, streetcar suburbs provide advantages to present-day traffic by dispersing vehicles in a variety of directions unlike sprawly street patterns which tend to focus traffic at increasingly congested nodes.

But here’s where the value of the grid system breaks down in Auckland. It’s not the fact that cars can traverse these neighbourhoods, which is good and creates a resilient network,  it’s that the street designs and road rules allow people to drive with impunity. It’s as if these streets are designed to serve an elevated network function when in fact they are foremost residential neighbourhoods.

Besides the crazy speed limits, most streetcar suburbs have little if any traffic control. In fact, more important than the speed limit is actually bringing cars to a full stop with regularity. This obviously slows cars but most significantly discourages through (rat race) traffic in the first place. Increasingly, I have witnessed the insertion of speed tables as a method of traffic calming. These are okay, but most drivers have an uncanny ability to slow and then speed up in perfect rhythm to avoid slowing down too much. Also, the speed tables seem incredibly expensive to achieve something that other cities can do with a lick of paint.

I see the best solution to fixing the suburbs for increased walkability and even cycling is to insert North American style crosswalks and stop signs. Of course this raises questions about pedestrian priority in NZ and the basic roadway designs that we have adopted from Canberra. As an example see the image from Vancouver below. It is a gridded neighbourhood about 6km from downtown Vancouver. Note the density and diversity of traffic control devices. The small red stripes represent stop signs and a simple stripe. Because of the road rules giving pedestrian priority and the fact that that the stripes are pulled back from the intersection, these work effectively as crosswalks, giving people on foot prominence and more comfort. Note also the partial street closures. Unlike cul de sacs, these retain the traditional network connectivity of the streetcar grid by accommodating people on foot and bike, but stop unnecessary through traffic. Not noted on the map is a “Bicycle Boulevard” that cuts through this neighbourhood with its associated sharrows, signage and other features.

Traffic control in streetcar suburb of Vancouver

Below is the same scale area in the Auckland neighbourhood where I live. The blue stripes represent giveways which have limited pedestrian value, especially since they are placed beyond the pedestrian desire lines, and since there is no pedestrian priority status in this country. The few stop signs also have limited function for people walking because of their placement and the status of pedestrians. Compare the density of traffic control devices. Sure the blocks are much longer, but  that should only emphasise the practicality of putting crosswalks on every corner.

Lack of control in streetcar suburb of Auckland

Because it seems pretty unsafe, I walk my kids to school here. Of course many parents drive, creating an absurd self-reinforcing cycle of car dependency in a neighbourhood originally designed for people.