Geneva, Switzerland

Mariana Barbosa and Nicolas Deville and their design team at ADAo architects create a dynamic bathing pontoon as part of the refurbishment of the Quai de Cologny for the city of Cologny in the Canton of Geneva in Switzerland.

In response to the recent needs for open water bathing expressed by the population, major Swiss cities have, for several years, been developing free and natural spaces dedicated to this activity. 

In Geneva, the refurbishment of the Quai de Cologny is part of this dynamic context, creating on the one hand new access points to the water for the general public and on the other hand natural areas comprising reed beds and aquatic flora. 

Thus, a sequence of alternating leisure and nature areas has been developed along the embankment.

The circular pontoon, the highlight of this lacustrine partition, is made up of two rings between which a curved wave-shaped bench is an inset. 

Tangent to the shore, this 800 m2 and 40-meter diameter platform allows bathers to swim either within the circle, in a sheltered area away from the waves, or outside in open water.

Given the size and exceptional beauty of Geneva’s bay landscape, it was paramount for us to create a structure based on simple shapes, with strong and assertive aesthetics. 

The circle, an infinite line, evokes the whirlpool, the ripple, the impact of a drop on the lake. Inspired by its natural environment, the pontoon’s pure geometric shape is therefore in motion, in a moving landscape.

Circular or spiral figures have always fascinated artists and architects, particularly in water-related contexts, as testified by the many examples of pontoons, pools, and works of land art created throughout the world. 

The circle is a figure that radiates and gathers in a movement both centripetal and centrifugal. 

As it evokes the idea of community, the architects found this shape to be particularly suited to a structure intended for the general public.

The top side of the pontoon is clad with an oak “casing” whose relief engages with the horizontal plane of the lake and the gentle undulations of the Jura. 

The rolling surface is based on the idea of creating a sort of “wooden dune,” thereby invoking images of the beach. 

The “pleated” expanse offers the general public a wide range of possibilities – sitting, lying down, leaning, meeting, etc. 

The circular shape offers a variety of viewpoints as well as different exposures to sun and wind. 

The production of this wooden surface involved 3D modeling the entire pontoon, detailing the beveled geometry and position of each of the 5’000 boards that make up the platform. 

This comprehensive method allowed for an optimal exchange of information between the architects, engineers, timber suppliers, and carpenters.

Although solidly anchored into the lake bottom, the pontoon is a “light” construction that gives the appearance of floating on the lake. 

Resting upon 24 piles driven into the molasse, the circular reinforced concrete platform creates a sort of shield which protects the decking from lake swell. 

Placed on the concrete slab, the undulating shape of the bench leans against a stainless-steel structure reminiscent of the ribs of an aircraft wing. 

As a result of extensive research, Swiss oak was chosen for its traceability, the availability of stocks, of planks, its exceptional durability, the lack of splinters and seepage, and its reasonable cost. 

Easy to maintain, it will acquire a patina and become grey over time, but without compromising its durability. 

The use of locally sourced wood, in a short supply chain, is a major bias on the client’s part as it is synonymous with a favorable ecological, social, and economic outcome both for Geneva and Switzerland in general.

Project: Lacustrine Installations, The Circular Pontoon for a Dynamic Context
Architects: ADAo architectes sàrl
Design Team: Mariana Barbosa and Nicolas Deville
Collaborators: CERA SA Ingénieurs Civils, Le Collectif Sàrl Ingénieurs Civils, SD Ingénierie Civile, SA BIOTEC Biologie appliquée SA, GEOS Ingénieurs Conseils SA, GREN Biologie appliquée Sàrl, ECOTEC Environnement SA
Client: Commune de Cologny et Etat de Genève, Service du lac de la renaturation des cours d’eau et de la pêche
Photographers: Fabio Chironi, John Magnin, Sandra Pointet, and Renaud Marion