Sloping sites: allies for denser cities

Urban densification projects are rife across Switzerland. But public enthusiasm remains muted and political pushback is on the rise. So how can we continue to meet demand for housing without eroding quality of life in our cities?

For my PhD research in architecture and urban sciences at EPFL, I decided to focus on neighborhoods built on slopes. Unobstructed views, favorable microclimates and easy access by car make these complex environments attractive places to live. But as urban areas, they tend to serve a secondary, single-use function. This observation applies to most of the suburbs that have been built since the advent of the motor vehicle. But it’s especially true of sloping neighborhoods, where the scarce patches of flat ground needed for public spaces are monopolized by cars.

By re-examining these sites through the lens of the urban transition, I was able to pinpoint neighborhoods that are strong candidates for accommodating new housing and other functions.

Mapping potential sites

Any effort to promote new forms of urban qualities and low-carbon transportation in sloping neighborhoods has to start by making public transport more accessible. As the first step in my research, I mapped sites in four metropolitan areas in Switzerland: Vevey-Montreux, Neuchâtel-La Chaux-de-Fonds-Le Locle, St. Gallen, and Sion-Sierre. My findings revealed an extensive network of public trains, funicular railways, gondolas and trolleybuses criss-crossing the undulating terrain, with numerous stops on already inhabited slopes. By re-examining these sites through the lens of the urban transition, I was able to pinpoint neighborhoods that are strong candidates for accommodating new housing and other functions – precisely where the need for densification is most pressing.

My goal is to gain both a broader and a more granular understanding of the issues by addressing them at the scale of an entire neighborhood.

Creating public spaces in sloping neighborhoods

The second part of my research looked at how these neighborhoods might be densified. For all its advantages, steep terrain poses challenges when it comes to public spaces. Historically, Swiss villages, towns and cities have managed to overcome this hurdle, offering high-quality housing and an excellent standard of living. Drawing on these precedents, I sought to tap into the opportunities offered by urban topography and offer insights into how to surmount the many constructional, spatial, landscape and climatic challenge presented by steep terrain. These kinds of complexities are often addressed at the scale of a single building, which is treated like an object set into the slope. Instead, my goal is to gain both a broader and a more granular understanding of the issues by addressing them at the scale of an entire neighborhood.

Through pilot projects at four test sites in the urban areas I’ve mapped, I intend to show that creating high-quality public spaces in sloping neighborhoods is not an insurmountable challenge, and that urban topography presents an opportunity to diversify the supply of attractive housing stock while also meeting the myriad challenges of the urban transition.

Clément Cattin, doctoral assistant at the Laboratory of Architecture and Sustainable Technologies (LAST), EPFL

• This article appeared in October 2025 in three local dailies – La Côte (Vaud Canton), Le Nouvelliste (Valais Canton) and Arcinfo (Neuchâtel Canton) – under a joint initiative between EPFL and ESH Médias to showcase the R&D being carried out at EPFL on advanced construction techniques.