Thread by @mindstalk

"15 minute city" explained, by an actual urbanist. Thread.

A 15 minute city consists mostly of 15 minute neighborhoods. 1/

A 15 minute neighborhood has, in a slow 15 minute walk, at least 2 grocery stores, 1 elementary school, a bank, post office, public library, pharmacy. Plus small parks and assorted other neighborhood businesses. 2/

It need not include a large high school, hospital, museums, college, or specialized jobs.

I know, some people do say "has everything you need in 15 minutes", but they're being sloppy. That's not feasible even at high densities. 3/

The point is not that you can't leave. The point is not that you never choose to leave. The point is not that you can't drive. The point is entirely that you _can_ meet many/most of your non-job needs without having to drive. 4/

Is it realistic? I've spent most of my life in such places, even in the USA, even outside of NYC. So yes. It's _real_. I would say it happens naturally when government zoning doesn't prevent it from happening. It's how our pre-car cities lived. 5/

pre-car cities and towns, I should say. 6/

Math: real walkable neighborhoods start around 9000 people/km2. A 15 minute walk on a street grid covers more than 2 km2. So that's 18,000+ people.

Enough customers for 2 full supermarkets, 9 convenience stores, and dozens of restaurants. 7/

Also around 1600 kids between the ages of 6 and 13, though only 800 kids between 14 and 17. So you can have elementary schools, and a small high school, but a big high school might need going a bit further. Likewise a big hospital might be further. 8/

All that is at a slow walk. If the streets allow safe biking, then even a slow bike speed covers 180,000 people in 15 minutes. Allowing access to _lots_ of options. 9/

Add in some decent public transit for going further, and that's it. Not an area where you're trapped, or that bans cars. Just a place where people can live decently even if they choose not to own a car, or can't drive. 10-end-unless-I-think-of-more/

Belated tags: #cities #urbanism #15minutecities #15minutecity #walkable 11/end-2

Ah! Something important to add.

If 15-minute cities are as reasonable as I make them sound, why do they need advocates?

Because currently, they're illegal.

12/

At least in the USA: government regulation (zoning) typically prohibits living at high enough density to support such businesses.

Government regulation prohibits opening such businesses in "residential" zones.

13/

Local governments now favor building big schools on the edge of town, needing cars, rather than ones that kids could walk or bike to.

Governments favor or at least allow cul-de-sac designs where street distances are too far to walk or bike. 14/

Mostly, 15-minute advocates don't want government to _do_ much, at least in this respect. Just get out of the way. Make it legal to build apartments and open grocery stores or dentists' offices, etc. 15/

A very 'conservative' approach, if conservatives really cared about property rights and individual choice as they claim to.

16/

(Also governments putting schools and libraries back in sensible places, and enforcing a grid at least for people on foot or bikes.)

17/

Link back to the start of thread:

#cities #urbanism #15minutecities #15minutecity #walkable

18/end-3

https://twitter.com/mindstalk/status/1627753815612223490

Someone else's great thread, with photos and different angles.

https://twitter.com/stevemouzon/status/1627469876678782976

Another coda:

I grew up in a 5 minute neighborhood in Chicago. Old streetcar suburb that was swallowed up. Lived in another one in San Francisco. They were great.

Cambridge MA, more like a 5-10 minute area, with some 15 minute outliers (including a large health clinic.) 19/

Now I'm housesitting in Berkeley, local density maybe 4500 people/km2. Still have 7 different markets around me, bunch of restaurants, a couple of post offices, ATMs, dentists, Carbon Health, etc. By my standards it's kind of lame and sleepy. 20/

One more tangent:

Many people used to 100% driving believe that the alternative is 100% transit, "taking the bus everywhere". It is not.

It's a mix of active transport (walk, bike, disability alternative), and transit as a range extender. 21/

I might choose to take transit to some specialty store. But if I can't walk to buy groceries, including fresh meat and produce, then the area is a failure as far as I'm concerned.

22/

Obligate transit should be for job, school beyond a regular elementary school, medical, museums, bigger or more specialized stores than your neighborhood supports. 23/

What about enabling carless life in existing local density areas? I'd guess an emphasis on safe and direct bike routes.

At 2000 people/km2, like 1/4 acre lots, slow biking covers 20,000 people in 15 minutes, like my walkable neighborhood earlier. 24/

At 1000/km2, you could still kind of do it, but giving up having two competing supermarkets in easy bike range. Threat of driving might keep them in line.

25/

I rediscovered one of my influences:

Differences: they assume lower density (5200/km2 vs 9000) but faster walk/bike speeds. And use Euclidean area (pi*r^2) vs. Manhattan/grid area (2*r^2)

26/cnu.org/publicsquare/2…

Math error earlier: "At 2000 people/km2, like 1/4 acre lots, slow biking covers 20,000 people in 15 minutes, like my walkable neighborhood earlier."

That biking covers 40,000 people. You get 20,000 with 1000/km2.

27/

Area of diamond with side s is 2*s^2
Take s=3.3 km in 15 minutes, speed 13 kph or 8.2 mph:

area is 20 km2, * 2000 people/km2 = 40,000 people.

28/

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