I’ve seen a bit of discussion recently on how dense we are in Christchurch compared to other cities around Australasia.
Density is very easy to measure – it’s simply the population (which we collect every census) divided by the land area (which we know from maps). However it is notoriously easy to misinterpret, because it can vary hugely depending on what land area you choose to include in the denominator e.g. do you just use the land covered by homes, or do you include streets, parks, industrial areas, rural areas, rivers, etc.? The average density of Christchurch is about 1,300 ppl/km2 if you just look at the urban area, but it drops all the way down to only 270 ppl/km2 if you include the entire land area of the city (which includes all of Banks Peninsula).
That said, there is a fairly standard way of comparing densities across different cities and it’s extremely simple. You just draw a grid of 1km by 1km squares across the city and look at how many people live in each square. These are published for every city in both Australia and New Zealand. I’ve taken snips of the bigger centres and chucked them below for easy comparison. In some cases I’ve drawn in either planned or recently built MRT schemes where I think it’s of interest.
First up, Christchurch. You can see that rural and industrial areas are less than 1,000 ppl/km2. Most of suburban Christchurch is between 1,000 and 4,000 ppl/km2, with a few pockets of 4,000-5,000ppl/km2 near the central city. Note that these numbers are as per the 2018 census, so the gap in the central city would have filled up now and most of the inner suburbs would be slightly higher.
Here’s Wellington at the same scale. The city centre is quite a lot denser, but outside of that densities are comparable to Christchurch. The northern part of their planned Light Rail line goes through areas that are quite a bit denser than Christchurch’s but the southern part is not dissimilar.
Auckland. Again, densities in the central city much higher and also some quite high density peripheral centres. Outside of those area, densities are comparable to Christchurch. Like Wellington, the northern section of their planned light rail goes through areas generally denser than Christchurch, but the southern section is similar.
Hamilton:
Tauranga:
Queenstown:
Now we head across the ditch to Australia. First a few of the smaller cities that are more comparable to Christchurch.
Canberra, smaller and less dense than Christchurch, built a 12km light rail line in 2021.
Newcastle, also smaller and less dense than Christchurch, built a 3km light rail line in 2019.
Gold Coast. Smaller than Christchurch, they built light rail in 2014. The map below makes it look like it’s similar density to Christchurch despite having enormous high-rise towers in some places. I think this is because it only counts residents. If you include tourists it would jump up quite a bit.
Hobart. Smaller and less dense, and no MRT as of yet:
Now to the bigger cities. These aren’t particularly comparable to Christchurch but we’ll have a look anyway.
First up Sydney. Absolutely massive and very dense.
Melbourne. Also massive and dense.
Brisbane. Not quite so massive but still a lot bigger than Christchurch. Outside of the central city it is comparable density.
Adelaide. Still bigger than Christchurch but similar density.
Perth. Again bigger than Christchurch but similar density.
All up, I think it’s quite interesting comparing these maps. Anything stand out to you?
Source: NZ: https://statsmaps.cloud.eaglegis.co.nz/portal/apps/storymaps/stories/aefd5509468a4b81b09c9c9a928b1719
Australia: https://absstats.maps.arcgis.com/apps/MapSeries/index.html?appid=2a01ccca01f047929b2efa9e2999d55d
TALKING TRANSPORT 
Hi Chris Morahan,
A guy in Aus you probably aware of called ‘Under the Clocks’ blog page doesn’t go much on population densities. Prefers to talk about actual numbers.
It beggar’s belief that Christchurch doesn’t have a BRT or regional rail network given its history. Maybe talk about ceding from the North Island, that might bring the NZ Gov’t to its senses.
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I David. I actually wasn’t aware of that blog but will take a look. Yea to some extent density is a red herring because it is the result of conscious town planning choices which could’ve easily been different and will certainly be different in future. But it’s still something that seems to keep coming up as an excuse for not doing MRT.
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Hi Chris.
To my mind Christchurch CBD needs light rail to cover at first the CBD connected to an interchange then more dense inner suburbs. Same as here in Newcastle Aust.
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So is light rail needed to move people within that dense area or to and from it? It would seem to Mr that people live in the dense areas to have easy and close access to the facilities they want. It’s people coming into these from the less dense areas that would most benefit from a light rail system.
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I’d probably see it as connecting up multiple dense areas e.g. Riccarton/university with the central city. There are different offerings in different areas that people will want to access. E.g. I love living in a neighbourhood where probably 90% of my daily needs can be met locally, but I still commute into town for work and I still travel to other neighbourhoods for various things.
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Living in Rolleston, which has a very high reliance on cars, I would love to see the light rail extended to here (as well as Rangiora, Kaipoi, Lincoln etc). Bus travel times on the regular service takes an hour from Rolleston to the exchange, which is too long for most commuters. An express bus is a bit faster. We urgently need a fast reliable service into the city, as I’m sure the other satellite towns do.
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Hi Keith,
The MRT (light rail or BRT) being proposed for Chch only goes to Hornby & Belfast & would require interchange there if coming from further afield.
We have a existing rail system that could be used and would provide a much more enduring solution for Chch although it would be more complex and probably more costly.
Direct service from Rolleston, Kaiapoi & Rangiora + park n ride opportunities for those in Lincoln, Woodend & Pegasus. BRT or bus priority could run to every station on the rail network.
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Hi Chris.
I think light rail only operates in limited areas where the population density is sufficient to generate passenger numbers.
The guy talking about Rolleston is over 20 km out from Christchurch and as such is commuter rail territory.
In my humble opinion, Christchurch needs to re-establish, a new interchange will bus, light rail and heavy rail in the old location, open a connection on the northern line to it and recommence regional rail services to outlying areas. Light rail can service in the city suburbs, including the university etc. But Christchurch desperately needs better public transport to outlying centres
Newcastle NSW
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