Thread by @HowardFMaclean

Alright, after some chat about decentralisation last night, How Canberra Became The Worst City for Transport in Australia Due to Urban Planner Driven Decentralisation, a thread.

To begin with, this is Canberra - a city ~40kms long and ~25kms wide, pop ~474,000 or so.

Canberra is (as most people know) an incredible example of intentional urban sprawl. This happened chiefly because Peter Harrison, the NCDC chief planner in the 60s, really hated cities, apartment and terraces.

This led him to be a champion of car dependent suburbia, and led to one of the most insane plans for car based sprawl anywhere in the world, the Y-Plan, where Canberra would keep creating self-contain urban villages out to 100s of kms away.

Now the exact rationale for the Y-Plan among Canberra urbanists is something of a topic of debate. The original consultation had only one objective - reducing congestion via some really primitive 1960s traffic modelling.

But it's also true that over time, the Y-Plan acquired this folk rationale of also being about this idea that we could segregate our city into these "urban villages" that people wouldn't need to leave - work and play in the same local area.

This was only possible because the NCDC had both virtually unlimited money, no democratic accountability and complete power to reallocate employment by ordering government departments to move. Try this anywhere else, and reality and economic gravity would intervene to stop it.

And of course, as soon as the NCDC was dissolved with self-government in the 1989, it stopped. Employers moved to where they always wanted to be - in civic in the centre of Canberra. East Gunners has been waiting for a major government employer that will never come for 30 yrs.

But a lot of government departments were successfully scattered, notably the Department of Social Services in Tuggeranong, on the extreme southern periphery of Canberra.

What happened of course is that the urban village model broke down. People moved jobs. Households formed between couples where they had different jobs in different districts. Which means, in Canberra, commuting from Gungahlin to Tuggeranong is pretty common.

A 45 minute plus commute in a city of less than 500,000 people is insane. It's a similar commute as working in Melbourne City and living in Croydon, except Canberra is an order of magnitude smaller than Melbourne.

This is reflected in the commute times data from Grattan. Canberra's median commute distance is actually around the same as Sydney, and its median commute time is longer than Adelaide, a city almost twice our size.

The challenges of decentralised employment centres for city as labour markets was put forcefully by Alain Bertaud in Order without Design. Dispersion means that transport challenges are just much harder to ensure effective labour markets.

The scale of this failure cannot be overstated. Canberra is the only major Australian city built for the car. The only city planned for it. We had huge amounts of resources for transport planning and infrastructure. And for our size, we ended up the worst of the pack.

CBDs exist for a reason. They maximise urban agglomeration effects, knowledge spillovers and increase productivity, but they also minimise commuting times for potential workers. The centre is the centre. This minimises transport infrastructure requirements via radial networks.

By contrast, in Canberra we have spent huge sums of money creating an elaborate system of orbital freeways designed to not get people from the edge to the centre, but from edge to edge (because of decentralisation). This is expensive for a city of under 500k people.

Going forward, dealing with the legacy of the Y-Plan will be a big challenge, to keep congestion and commuting costs low. Increased density in inner ring suburbs is a major step, but chances are we're going to be spending many more billions on transport as a result.