Time-oriented planning for sustainability – UrbaTime

Three analytical dimensions were mobilized:

(i) The production of project temporalities:

This dimension focused on actor dynamics and the renewal of professional practices, marked by the emergence of new fields of expertise. These evolutions contribute to a growing complexity in the temporalities involved in urban development operations.

(ii) Spatial effects over time:

This dimension explored how short-, medium-, and long-term horizons are articulated within specific urban projects. The aim was to demonstrate how the logics of prefiguration, experimentation, intensification and spin-off that shapes these projects correspond to action objectives, categories of relationship to time and project phases.

(iii) Knowledge production and circulation:

This dimension examined how knowledge is produced, circulates, and is contested within a context of globalized planning models, references, best practices, and methods. Particular attention was given to the tensions between generic solutions and locally grounded alternatives, as well as the activation of situated knowledge.

The analysis was grounded in empirical research conducted in Bordeaux, Lyon, and Montréal (and, to a lesser extent, Lille)—economically influential and demographically growing metropolitan areas with urban policies that position themselves as innovative. Cross-comparisons were carried out at local, national, and international scales. A comprehensive analysis of planning practices in each metropolis was undertaken to establish a shared institutional and spatial baseline, enabling a better understanding of the progressive deployment of temporary actions within the broader urban production process.

Semi-structured interviews were conducted with urban planning professionals recognized at the national and international levels (15), as well as with key actors involved in the selected metropolitan areas and development operations—elected officials, municipal planners and technicians, developers, designers, and members of civil society organizations (91). Field observations and guided visits with practitioners were also carried out on the sites of the studied operations.

A wide range of documents (technical guides, communication brochures, newspaper articles, reports, meeting minutes, websites, etc.) were analyzed—both for the information they provide on urban policies and specific projects, and for their role in spreading knowledge and practices, particularly in representing project temporalities and transmitting references. This led to the creation of several databases, including an inventory of transitional and tactical urbanism guides, as well as a registry of temporary urban projects in Bordeaux, Lyon, and Montréal.

Finally, participation in various events (conferences, presentations, and seminars) focused on ephemeral, transitional, and tactical urbanism provided insight into the discourses shaping professional, political, and public understandings of temporality in urban planning.

Over the course of three decades, the UrbaTime program traced the emergence and development of urban actions—whether described as temporary, tactical, or transitional—within the production of urban space across several metropolitan areas. This work highlights the increasing acceleration and normalization of temporary practices, which have become embedded in the planning tools of various cities, even if not yet fully stabilized or institutionalized. This integration has not followed a linear trajectory but has instead been shaped by phases of emergence, acceleration, deceleration, and divergence. In particular, the COVID-19 crisis of 2020 significantly intensified the use of temporary actions across all case studies, with effects extending well beyond the immediate context of the pandemic.

The proliferation of temporary projects brings into play multiple and sometimes conflicting urban logics and temporalities. Some initiatives introduce alternative temporal frameworks and visions, challenging conventional planning approaches through experimental logics. Others, however, display limited adaptability and adhere more closely to traditional project phasing, with little critical reconsideration of existing planning paradigms.

The research reveals a wide variety of temporary projects—not only in terms of the actors and objectives involved, but also regarding their relationship to time, especially in how they are embedded (or not) within longer-term trajectories. The program documented projects ranging from a few days to several weeks, often implemented in public spaces, as well as longer-term temporary agreements—lasting several years—mostly situated in vacant buildings or unused facilities. The relationship between these temporary actions and longer-term urban projects proved highly diverse. Three main patterns were identified: (1) some actions remain isolated instances, though such cases are relatively rare; (2) others are deployed in cyclical forms; (3) and some are integrated into longer-term urban development projects, although the processes enabling such integration vary considerably.

Finally, the program examined the circulation of knowledge, with a focus on the actors who facilitate this process and the nature of their practices. Across different contexts, public institutions, non-profit organizations, and private companies play key roles as "passthrough translators", adapting and disseminating these practices across scales. Special attention was given to the tools supporting this knowledge circulation, particularly the growing number of professional guides on temporary and transitional urbanism that have emerged in recent years. The analysis shows how such guides contribute to a broader conversation around the development of temporary urbanism and its integration into local public policy frameworks.

Several avenues for further reflection emerged over the course of the UrbaTime program. First, two dedicated research programs extended and deepened the analysis. To examine particularly complex urban projects in greater detail and to fully engage with the question of transitional urbanism, part of the research team joined the TransUrba program, titled Transitional Urbanism in Support of Ecological, Economic, and Social Transitions in Territories (PI: S. Mallet, 2022–2025), developed in response to the TEES call for projects issued by ADEME. In parallel, the tactical urbanism initiatives deployed in French cities during the COVID-19 health crisis were specifically examined through the research project MUTaction – Mobility and Tactical Urbanism in Action, conducted within the framework of the "Résilience Grand Est" call (2020–2022, PI: C. Burger).

Subsequent research has been undertaken within the framework of doctoral theses. The thesis of M. Michaux, funded through a CIFRE agreement with the City of Paris and co-supervised by S. Mallet and A. Fleury since 2024, investigates the relationship between transitional urbanism and festive or event-based activities. Building on analyses initiated within the UrbaTime program, L. Michaud’s dissertation, directed by S. Mallet and funded by the University of Reims Champagne-Ardenne (URCA), explores third places and the circulation of knowledge. Lastly, the doctoral project of Y. Kaiava—co-supervised by A. Fleury and S. Barles—on the integration of seasonal cycles in the production of public space, follows a master’s thesis on seasonality and cyclical time and an internship completed as part of the UrbaTime program.

Other potential research directions are also emerging: 1/ While the issue of knowledge circulation in the field of temporary urbanism was initially addressed within UrbaTime, it requires further exploration. A project was submitted at the end of 2024 by S. Mallet to study the diversity of professional arenas in temporary urbanism (seminars, training programs, professional publications, etc.). 2/ Questions concerning the future of temporary site occupants remain largely underexplored. Many such sites host artisans or small businesses whose tenure is limited and lacks a clear pathway for transitioning to long-term integration of their activities. 3/Temporary urbanism is also reshaping the roles and practices of planning professionals, particularly in project diagnosis and implementation processes. It has contributed to the inclusion of previously peripheral actors—such as artists—into the field of urban development. This transformation of professional practices and participatory modalities remains a promising area for further research.

The UrbaTime program has thus opened up a variety of research trajectories, many of which are already the subject of ongoing academic inquiry.

The UrbaTime project purpose is to understand the way in which time can be integrated to policies aiming to build the sustainability of urban systems. To achieve this objective, a transversal analysis of various contemporary urban conceptions, suggesting a different way of thinking of the relationship between planning and time, will be conducted. This study is essential as part of the sustainable planning building process because 1/ The study of sustainable cities and sustainable urban planning is rarely considered from a temporal perspective, although the notion of sustainable development is intrinsically time-oriented; 2/establishing sustainability in the production and management of urban spaces goes hand in hand with the growing importance of certain urban planning conceptions, as temporary urban planning, flexible urban planning, tactical urbanism, ephemeral urbanism...These conceptions are based on short periods of time or revising the traditional phases of urban projects. The dissemination and success of certain innovative urban planning conceptions are a clear indication pf a transformation of urban planners' relations to time. However, this transformation has not yet been really questioned by researchers. Time is still a relative unthinkable element of urban research, although some researchers have been calling for its study for a long time now, notably in its links with sustainability.
The researchers of the project put forward three hypotheses: (H1) time is a key element in the construction of a sustainable city; (H2) the urban planning conceptions under study renew how time is considered in urban planning. The new, temporalized conceptions highlight the extent to which time is a strategic resource; (H3) these conceptions reinforce the sustainability of urban systems. This hypothesis is regularly highlighted by the operational stakeholders of urban planning, but still needs to be tested scientifically.
Studying the temporal dimensions of urban planning operations and their links with the objective of constructing sustainable urban systems requires addressing a methodological challenge. The UrbaTime project suggests an original approach centered on the construction mechanisms of time by stakeholders, as well as their arbitrations. The project thus proposes three inputs for the analysis: (1) the study of the elaboration and circulation of knowledge, (2) the study of making of the project's time frames by the stakeholders, (3) the study of the socio-spatial effects over time.
The analysis of these three inputs will be made possible through an important empirical work based on three cities: Bordeaux, Lyon and Montreal, and some intersections will be done at several scales: local, national and international. The data collection methodology is based on the mobilization of stakeholders, the collection and analysis of documents, the attendance to meetings.
The project will provide in-depth knowledge of successful urban concepts that have not yet been subject to a cross-cutting analysis. It will firstly try to shed light on their nature, their dissemination, the circulation of knowledge to which they are subject, especially in terms of knowledge of urban time frames and their mastery. The project will help better understand the representations of time of the stakeholders, the way they are mobilized, or even the construction of common project timeframes. Finally, the research will shed light on the sustainability of the socio-spatial effects of the conceptions under study, in order to have a better understanding of possible articulations of time, especially between short term and long term actions.
One of the major contributions of the research suggested is to respond to the growing demands for public policy expertise concerning the temporalities of the urban fabrication and to provide an operational reference framework for the sustainable city.