The ask

The “15-minute city” has been promoted globally, by many city mayors – most famously Parisian mayor Anne Hidalgo. When the sprawling, car-dependent City of Nanaimo began touting the idea that it could become such a city, I wondered if it was possible to quantitatively evaluate how close or far a city is from approximating Moreno’s model. It seemed obvious that a city with Walk, Bike, and Public Transit Scores in the mid-30s could not possibly be a 15-minute city overall. But what about certain city districts? Were some neighborhoods more car-dependent than others? And if they were, could this be changed?

Thought process

How to capture where a 15-minute city in fact exists?
What makes a 15-minute city at minimum?
15-minute access to essential and basic quality of life amenities.
How to define these things?
Use some officially accepted standard. And to establish a baseline understanding of where a 15-minute city exists, use walkability as a proxy for universal access, realizing that while not everyone can walk, it still represents a very widely accessible means of transport.
People need different things. Some have kids in school. Some need a walk-in clinic or a foodbank. Those with low or no income may have to live in supported housing or a shelter. In other words, your need basket determines the places you could live and have 15-minute walking access to everything you need.
Once you've determined baskets of needs corresponding to different demographic groups, one needs to work backwards from need-baskets - 1 scrape for amenity locations, 2 map 15-minute walking isochrone zones around those locations, 3 find amenity isochrone overlaps for amenity baskets / groups.

What I did

First, I created a list and google maps-scraped "essential" amenity locations – grocery markets, pharmacies, parks, schools, and so on. Next, I cleaned the scrape data, and mapped these locations' 15-minute walk zones using QGIS, and their overlap. These overlapping amenity-access zones would be 15: neighbourhoods.

To understand just how many people can live in and enjoy a 15: city, I overlaid my 15: zones on a population density map. And to get a rough idea of who can afford to live in these 15: zones, I superimposed my 15: maps on a median household income map.


Article in Spacing:Vancouver.

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