Rolly: A Modular Approach to Urban Regeneration Architecture on Paris’ Petite Ceinture

In contemporary cities, abandoned infrastructures often become overlooked fragments within the urban fabric. Yet these voids hold immense potential for reinvention. The project Rolly, designed by Yuna Kim, engages directly with this condition through an innovative approach rooted in urban regeneration architecture.

Located along the historic La Petite Ceinture in Paris, this proposal reimagines an obsolete railway corridor as an active, adaptable, and participatory public space. Recognized as the Organizer’s Choice Award entry of Salut Paris, the project transforms linear infrastructure into a living system of movement, interaction, and spatial flexibility.

Context: The Latent Potential of La Petite Ceinture

La Petite Ceinture once functioned as both a transportation network and a defensive boundary for Paris. Abandoned in the early 20th century, it has since evolved into a fragmented urban condition, simultaneously isolated and embedded within the city.

Rather than treating this infrastructure as a static artifact, Rolly positions it as an active framework. The project acknowledges the embedded logic of the railway, its linearity, continuity, and connection across neighborhoods, and uses these qualities as a generative design strategy.

This approach aligns with broader discourses in urban regeneration architecture, where the objective is not demolition or replacement, but reinterpretation and activation.

Concept: Mobility as Architecture

At the core of Rolly lies a compelling idea: architecture that moves. The project introduces a system of modular objects that can travel along the existing railway tracks, redefining how space is occupied and experienced.

These objects are not fixed interventions. Instead, they operate as mobile spatial units that can be rearranged, clustered, or dispersed depending on time, use, and user interaction.

The concept draws from the inherent linearity of the site. Rather than resisting this constraint, the design amplifies it. The railway becomes both infrastructure and circulation system, allowing architecture itself to become dynamic.

Design Strategy: Modular and Scalable Interventions

The project is composed of three primary categories of architectural elements:

1. Small Mobile Objects

These lightweight units are placed directly on the tracks and can be pushed or pulled by users. Their flexibility enables multiple functions such as seating, play structures, reading spaces, or informal gathering spots.

Their adaptability allows the space to continuously evolve, encouraging user participation in shaping the environment.

2. Medium Static Objects

Positioned along the retaining walls, these elements act as semi-permanent installations. Designed as retail or activity spaces, they include openings and perforations that invite interaction and visual engagement.

Their roofs extend the public realm vertically, creating additional layers of occupation and movement.

3. Large Central Structure

The central tent-like structure acts as the primary anchor of the site. During the day, it functions as a marketplace, extending the activities of adjacent street-side commerce. At night, it transforms into a communal gathering space for events and performances.

This dual functionality reinforces the temporal adaptability of the project, a key principle in urban regeneration architecture.

Spatial Dynamics: Day and Night Transformation

One of the most compelling aspects of Rolly is its responsiveness to time. The project is not static across the day.

• Daytime: Objects are dispersed across the tracks, creating a porous landscape of activities. The space becomes informal, playful, and exploratory.
• Nighttime: Smaller elements converge under the central structure, forming a cohesive social hub. The environment shifts into a more concentrated and communal configuration.

This cyclical transformation introduces a temporal layer to the design, enhancing its adaptability and relevance to different user groups.

Programmatic Flexibility and User Engagement

The project is designed to accommodate a wide range of users, including tourists, local residents, and diverse communities.

Rather than prescribing fixed programs, Rolly offers a framework for open-ended use. The movable objects enable spontaneous interactions, while the larger structures provide stability and continuity.

This balance between flexibility and permanence is critical in urban regeneration architecture, where spaces must respond to evolving social and cultural dynamics.

Material Logic and Construction Approach

The modular units are envisioned using lightweight aluminum structures, allowing for ease of movement and reconfiguration. Their geometric simplicity ensures accessibility while maintaining a recognizable architectural identity.

The use of basic forms also creates a sense of familiarity, reducing the psychological barrier for users to engage with the space.

Urban Impact: Beyond a Single Site

While Rolly is grounded in a specific location, its implications extend beyond La Petite Ceinture. The project proposes a replicable strategy for reactivating linear infrastructures across cities worldwide.

With hundreds of similar transit systems globally, many of which are underutilized or abandoned, the project presents a scalable model for urban regeneration architecture that is both cost-effective and socially engaging.

Critical Reflection: Jury Insights

The project has been recognized for its originality, yet it also invites constructive critique.

Rachel Luchetti (Juror):“Cute idea - needs development”

Fuensanta Nieto (Juror):“Project with the possibility of the creation of beautiful spaces but maybe because of the lack of development is missing the necessary connection to the city.”

These observations highlight an important dimension of the proposal. While the conceptual framework is strong, further refinement in urban integration and detailing could enhance its real-world applicability.

Rolly challenges conventional notions of architecture as static and fixed. By introducing movement, adaptability, and user participation, it redefines how public space can operate within existing infrastructure.

The project positions urban regeneration architecture not merely as a tool for preservation, but as a catalyst for transformation. It demonstrates that even the most overlooked urban fragments can become vibrant, dynamic environments when approached with innovation and sensitivity.

In doing so, Rolly offers a forward-looking vision for cities seeking to reconnect with their past while adapting to future needs.