The global distribution of the 15-minute city idea 5/7

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A previous post made it clear that a 15-minute city ideally consists of a 5-minute walking zone, a 15-minute walking zone, also a 5-minute cycling zone and a the 15-minute cycling zone. These three types of neighbourhoods and districts should be developed in conjunction, with employment accessibility also playing an important role.
In the plans for 15-minute cities in many places around the world, these types of zones intertwine, and often it is not even clear which type of zone is meant.  In Paris too, I miss clear choices in this regard.
The city of Melbourne aims to give a local lifestyle a dominant place among all residents. Therefore, everyone should live within at most 10 minutes' walking distance to and from all daily amenities.  For this reason, it is referred to as a 20-minute city, whereas in most examples of a 15-minute city, such as Paris, it is only about <strong>the round trip</strong>. The policy in Melbourne has received strong support from the health sector, which highlights the negative effects of traffic and air pollution.
In Vancouver, there is talk of a 5-minute city. The idea is for neighbourhoods to become more distinct parts of the city. Each neighbourhood should have several locally owned shops as well as public facilities such as parks, schools, community centres, childcare and libraries. High on the agenda is the push for greater diversity of residents and housing types. Especially in inner-city neighbourhoods, this is accompanied by high densities and high-rise buildings. Confronting this idea with reality yields a pattern of about 120 such geographical units (see map above).
Many other cities picked up the idea of the 15-minute city.  Among them: Barcelona, London, Milan, Ottawa, Detroit and Portland. The organisation of world cities C40 (now consisting of 96 cities) elevated the idea to the main policy goal in the post-Covid period.
All these cities advocate a reversal of mainstream urbanisation policies. In recent decades, many billions have been invested in building roads with the aim of improving accessibility. This means increasing the distance you can travel in a given time. As a result, facilities were scaled up and concentrated in increasingly distant places. This in turn led to increased congestion that negated improvements in accessibility. The response was further expansion of the road network.  This phenomenon is known as the 'mobility trap' or the Marchetti constant.
Instead of increasing accessibility, the 15-minute city aims to expand the number of urban functions you can access within a certain amount of time. This includes employment opportunities. The possibility of working from home has reduced the relevance of the distance between home and workplace. In contrast, the importance of a pleasant living environment has increased. A modified version of the 15-minute city, the 'walkable city' then throws high hopes. That, among other things, is the subject of my next post.