Hierarchy of centers for the 15-minute city

I recently spoke on a panel discussing the 15-minute city, and the cool graphic above was presented showing a hierarchy of mixed-use centers throughout the City of Portland, Oregon. This kind of analysis would help many cities plan to achieve an urban environment where owning an automobile is optional—or at least car-light living is possible. 

To achieve a 15-minute city, you not only need safe and interesting places to walk, but you also need useful destinations. That's where mixed-use centers come in. As the map above shows, there are 32 urban centers in Portland, but they are not all the same. Twenty-one are “neighborhood centers,” which can be defined as a small main street. Each neighborhood center contains about 2,500 households within a half-mile radius (a 10-minute walk from edge to center). 

Buildings may be up to four stories tall—but are often one to three stories—in these smaller centers. “Neighborhood centers are hubs of commercial services, activity, and transportation for surrounding neighborhoods. They typically include small parks or plazas that support local activity and gathering,” according to the city. They are scattered throughout Portland. 

The next step up is “town centers,” of which there are nine. They include housing for about 7,000 households in a half-mile radius, with buildings up to 5-7 stories. “Each Town Center is a hub of commercial and public services, activity, and transportation for the broad area of the city it serves,” the city explains. “Town Centers include parks or public squares to support their roles as places of focused activity and population. They provide housing capacity within a half-mile radius for enough population to support a full-service neighborhood business district.” Town centers are also scattered throughout the city, although less frequently than neighborhood centers.

Portland has one regional center, the Gateway Regional Center, a major commercial district serving much of the city—especially the eastern half. Finally, downtown Portland serves not just the city, but the entire region.

For Portland, identifying these centers is step towards boosting non-automotive access to services and employment for citizens throughout the city. Strengthening these centers may involve changes in housing or parking policy, or improving infrastructure—especially for walking, biking, and transit. Each center and its surrounding neighborhoods should have a diversity of people and uses to support a 15-minute city.  

Editor's note: This article addresses CNU’s Strategic Plan goals of working to change codes and regulations blocking walkable urbanism, to grow the supply of neighborhoods that are both walkable and affordable, and to advance design strategies that help communities adapt to climate change and mitigate its future impact.