Walk this way

File under: transport, urbanism, sustainability, Wellington

My last post on the Johnsonville Town Centre Plan seem to have generated a little bit of controversy, primarily involving an anonymous commenter with a familiar style. Just for the record: no, I'm not intimately familiar with J'ville and its environs, which is why I was asking for those with local knowledge to assist me with understanding why some seemingly handy blocks were omitted from the "intensification zone". It does sound like there are some access difficulties, though as this map (adapted from NZTopoOnline) shows, the overall gradient between there and the station seems relatively gentle by Wellington standards: only about 20m rise over a distance of 500m.

This all goes to show how complicated it is to define what a "walkable" distance is. The website Walk Score (via Lifehacker) allows you to search for an (American) address, then tells you how walkable that neighbourhood is by working out how far it is to the nearest shops, schools, parks and other amenities. Most of Manhattan scores near 100, while typical suburban and exurban locations are way below 50. It's a good concept, but the methods they use a far from perfect.

For a start, they use direct "as the crow flies" distances, thereby assuming that people could walk through the middle of rivers, buildings, railway tracks and motorways. This thereby ignores connectedness of the pedestrian network, which is a vital ingredient in a walkable neighbourhood. It also ignores terrain, which as the recent comment-storm has shown, is an important influence in a place like Wellington. The location and classification of the amenities they show is only as good as the data in the Google API, which is one reason why it won't work here yet: even though ZoomIn, for instance, has a database of many such amenities, it's not quite complete or organised enough to use for this purpose at the moment. Nevertheless, the Walk Score site gives a moderately useful indicator of mixed use and density, and is promoting a very important message.

I've been thinking about setting up some routing algorithms for walking distance in NZ, and while the basic concept should be simpler than for driving (there are no one-way streets or turn restrictions to worry about), it's much more complicated to come up with a truly realistic model. As well as distance, one would have to think about:

• slope
• waiting time at crossings (and we know how important that is!)
  
• joining up the entrances and exits of parks and squares
  
• opening hours of "quasi-public" shortcuts (e.g the lifts between Lambton Quay and the Terrace)
  
• foot traffic (grr, slow walkers on Willis St at rush hour!)

That should give a pretty good estimate of the shortest time it would take someone to walk from A to B, and thus the number of Bs there are within a given number of minutes from A (if that makes any sense). But even that is only part of the story: sure, maybe you can walk from A to B in five minutes, but would you want to? A blank, featureless environment makes a given distance feel much longer (hello, Harbour Quays), and shelter can have a major impact too: I'll often choose a longer route to work via Lambton Quay than the shorter but bitterly exposed walk along Customhouse Quay. Safety (or at least the perception thereof) is another factor, especially at night when routes that are too dark and deserted (most parks) or too rowdy (Courtenay Place late on a Friday night) will be avoided by many.

To their credit, Walk Score recognises the limitations of their technique, and link to some good articles on the complexities of walkable communities, much of which will escape the analytical capabilities of even the most subtle GIS system. It takes more than a direct, flat path to make people want to walk somewhere for something other than the daily trudge to and from work, and the irregular shape of the intensification zone shows that the planners have been taking at least some of these into account. The plan seems to be aiming for all the right things to make central Johnsonville into a place where people would not only be able to walk to work or the station, but actually feel good doing so and feel like hanging around at the weekends too. They've got a long way to go, but it's the necessary first step.