[talk-au] Classifying settlements (Was Re: Filling in blank space (Was Re: Tagging towns by relative importance, not just population size))

[Andrew Davidson]

On 2/10/23 21:53, Little Maps wrote:
> As I understand your message, we have and/or can get population data
> for a small proportion of places in Aus (probably with comprehensive
> data for most larger places and less data for the many smaller ones).

There are two classes of problems:

1. Urban centres that have gown so much that they have coalesced with 
neighbouring urban centres. Some of these are easy to assign the 
population to a single place node (Gold Coast, Nowra - Bomaderry, 
Shepparton - Mooroopna). Others are not clear where you would put the 
population (Central Coast, Blue Mountains, Ocean Grove - Barwon Heads). 
There are about 90 of these out of 1800.

2. Settlements that are so small that the ABS doesn't consider them 
worthy of their own mesh block (the smallest geographic unit they report 
on). If a settlement doesn't rate a single residential mesh block I'd 
say it's not really a candidate for anything above hamlet.

> This means that, if we develop a guideline based primarily on
> population data we then have to develop a simple way to extrapolate
> the guidelines to places without pop data. Yes?

If you can't get population data that kinda suggests it's either tiny 
or, grown so big that you have to start worrying about how to subdivide 
the urban area into suburbs etc.

> As a simple starting point, I’m curious whether it’s possible to
> first try to get agreement on general cut-offs for
> villages/towns/cities etc using only the places that have pop data
> (i.e. those you’ve mapped). We could present some different scenarios
> so that everyone could see the implications of different decisions
> for areas that they know.

The ABS uses a threshold of 1000 people in an urban area to identify an 
urban centre. In OSM speak this would be a town or city.

At the small end the old Natmap standard was not to show any settlements 
smaller than 200. Maybe that's the threshold for hamlet/village. 
Although I get the impression people would like to adjust that for the 
level of services available. Perhaps we could apply the Fitzpatrick 
adjustment:

add on or take off 50 people for each one of the following is or isn't 
available:

pub
shop
servo
a government service (PO/Hospital/Police)

So a settlement with pub, shop, servo, and school with a population of 4 
would be a village. A rural residential development with no services and 
a population of 750 would be a hamlet.

The cutoffs are going to be arbitrary. The important thing is to just 
choose some and make sure that there's some reasoning behind them.