This "scientific" article from Sony CSL about 15 min cities has been making the rounds in the news those past few weeks, and uhhh

As far as I can tell it's really bad research? It's based on OSM data without trying to compensate for disparity in coverage. It's based on some weird definition of urban areas that in some cases include several acres of uninhabited mountains, which reduce city averages. Basic mistakes.

https://csl.sony.it/project/the-15-minutes-city/
https://arxiv.org/pdf/2408.03794

For example, when Nature reported on this they included a graph showing Rotterdam as significantly worse than most other large european metros.

Looking at the maps... https://whatif.sonycsl.it/15mincity/15min.php?idcity=7421 it shows places like *all of Hook of Holland* being 30+ min away by foot from "supplies" (supermarkets) and "learning" (schools).

And the urban area includes the whole port of Rotterdam. Which, yeah, I can believe it's not a very walkable neighbourhood?

The reason why Hook of Holland is included is that it's part of the municipality of Rotterdam. The reason why it's shown as 30+ min is because the algorithm used by the researchers uses the average walking time to the **20 nearest POIs** in a given category. Which makes no sense when you have isolated "islands" (figuratively) like Hook of Holland, which really should count as separate towns. Just really bad methodology...