1Autonomy and independence in urban space have been the object of sustained interest for several decades. The questions surrounding these two key concepts in research and intervention on urban environments are mainly related to development processes. They are constantly renewed against the backdrop of issues emerging from the evolution of societies or their living environments. For example, the demographic transition of industrialized countries bring into play new population and diversified household profiles with contrasting needs, preferences and aspirations that have never been observed before.
2We need only think of children and adolescents, or young retirees and seniors. They find themselves with living conditions and ways of adapting to the urban environment that are constantly changing, especially with the evolution of technical or technological devices for getting around and communicating. Profiles of more vulnerable people, in terms of resources or residential location, are also the object of interest in the research. As such, urban accessibility, gentrification, and the impact of large-scale urban renewal operations, represent inescapable questions. More broadly, the imperatives of climate change also call for a renewed questioning of sustainable development in inclusive cities. The insertion of non-motorized modes of transport in the city can offer a wider range of modal choices and address new inequalities linked with the massive use of private cars. This implies constraints and rationales that go beyond the replication of solutions and devices in different living environments within cities. Moreover, these issues all require the perspective of time and change to be considered.
3Thus, individuals, households and their living environments evolve according to relatively contrasting times, periods and cycles. In some cases, these times are not aligned and in correspondence with individuals' projects. For example, at a given moment, a suburban environment may be perfectly adapted for families. Then, with the children gone, these same environments may be functionally ill-adapted to the needs of elderly people. These same car-dependent suburban environments can also be questioned and challenged from the point of view of the sustainable evolution of metropolitan environments. The diversification and evolution of the suburbs can change the very functioning of the city and have an impact on all of its inhabitants. The same observation can be made beyond residential environments, this time from the perspective of the city, its infrastructures or its resources. The question of the individual capacity to adapt then arises as well as the involuntary realignment of life trajectories or individual projects.
4In this context, independence and autonomy are two fundamental processes that characterize how individuals control their mobility and the territories in which they move. This themed issue intends to address the various pivotal periods in the life course that appear fundamental for spatial mobility: childhood, adolescence, working life, retirement and old age. One-off, less predictable events can also interfere with the autonomy process by influencing freedom of choice or even access to the urban environment: job relocation, residential mobility, a family break-up or health problems. We put forward that daily travel behaviours, but also the urban territories and resources that are their corollary, are inclined to change in both short term (modification of schedules or routes, changes of destination...) or longer-term, following a biographical event (birth of a child, divorce or marriage...) (Scheiner, 2007, 2018). Similarly, these changes will follow rationales that are related to the individual and his or her evolution, others that are more related to the urban context and more macro-sociological logics.
5In this long-term perspective, which is covered by the concept of "Mobility biographies" (Lanzendorf, 2003), some studies discuss the impacts on ordinary, daily travel behaviors related to these events, which vary in their intensity and predictability. There is a growing body of research on the relationship between biographical transition and everyday mobility (i.e. special issue of Transportation Research Part A, Zhang and Van Acker 2017, or more recently a special issue in Sustainability, Gerber et al. 2021), but little research related to biographical bifurcations, which often remain confined to situations related to inequalities or to key milestones in the life course, such as aging or family life (Lord et al. 2015; Lord and Piché, 2018).
6Whether in one or another life-course framework, the questions allowing this kind of research are still ongoing. In this context, this thematic issue aims to bring together theoretical, methodological, and empirical perspectives on the evolution and changes of travel behaviours according to two main notions in current research: 1) “transitions” (Bronfenbrenner, 1986) and 2) “bifurcations” (Abbott, 2001; De Coninck, Godard, 1990) that households and individuals are living. Certain periods of life (childhood, adolescence, old age, for example) imply approaching the experienced changes in daily life from relational approaches. The dynamics of cities and places are already well studied in relation to the dynamics of social contexts in connection to migration and residential mobility (Bonvalet, Ogg, 2006; Canzler et al., 2008). However, relational approaches must also be strengthened in the context of urban mobilities (Baslington, Hazel. 2008) and on the idea of linking different forms of mobility (or even scales or social groups in relation to each other). Such approach makes it possible to consider the interlocking spatial and temporal scales, as well as the relationship between the mobilities of different members of a social group such as the family (Demoraes et al., 2021).
7In either research context, questions that allow for this type of methodological approaches are rare and/or underdeveloped in their conceptualization of time and change. This themed issue intends to contribute within that context by putting forward original research in the scope of person-environment research from environmental psychology, geography, planning and urban sociology.
8In this issue, we wish to bring together theoretical, methodological and empirical work on the evolution of and changes in mobility behaviours that households and individuals experience in time and in the course of their biographical path. Thus, among the questions that can be raised, do bifurcation and transition reflect a biographical reality experienced by individuals? Does a bifurcation generate more changes in mobility routines than a transition? What is the role of socio-spatial constraints and contexts (accessibility, urban form, family and social networks, schedules, types of activity, etc.) in behavioral changes following a biographical event? Knowing that the evolution of mobility experiences varies according to social, spatial, and cultural contexts, relationships to time and space evolve according to certain transitions. This raises many issues and showcases the needs for innovation in mobility research methodologies to consider biographical data and its analysis. These same issues, when it comes to knowledge transfer, also bring challenges in the adaptation and planning of urban environments.
9The first contribution of the issue is by Maya Elnesr entitled “Impact of residential everyday urban space conception on children community play behaviour and cognitive development (case study Cairo and Paris)”. The author is architect and presents research on the design of urban spaces and the impact of this design on children's play behaviour and development. The international case study is based on two urban neighbourhoods, one in Paris, France, the other in Cairo, Egypt. From a theoretical point of view, the article questions a precise moment of the life course in full change, by putting in perspective the potentialities of transition and bifurcation in the development of children in preadolescence. These are approached according to similar urban typologies in the two countries, but with different urban and cultural configurations. Using a comparative approach, the study was conducted through observations, perceptual cognitive skill activities and interviews. The contribution provides a better understanding of the configuration of children's preferred urban environments, their daily sensory experiences of these places, the events they enjoy and the activities that constitute their daily lives. If the study renews the idea that children's experience of place is multidimensional, it is through detailed analysis that the author shows in comparative cultural settings the importance of variety and diversity in the construction of experiences capable of being mastered as a transition in urban space. And this variety can potentially equip people for their continued development in the subsequent ages of the life. In this sense, this contribution can echo Després’ fifth contribution on the times and ways in which older people refocus their daily lives on their homes. In terms of results, Elnesr's study opens up a new perspective in the design of urban space where places should not be thought of for children as closed sites, but rather as environments for all, intergenerational, and child-friendly.
10The second contribution by Sandrine Depeau, Kamila Tabaka, Pierre Dias, Sylvestre Duroudier, Colin Kerouanton, Arnaud Lepetit, Sonia Chardonnel, Isabelle Andre-Poyaud, Boris Mericskay and Eva Moffat is entitled "When children move to middle school: a small transition or a major change in their autonomy?" The authors from environmental psychology and geography are interested in understanding how children's autonomy changes during a transition from elementary to middle school in France. The autonomy of children and adolescents is studied through their independent daily movements, the location of their preferred places, and by observing their ability to cope with unexpected and unfamiliar situations. Following a two-stage longitudinal approach, capable of approaching transitions, the results show differences in the mobilities of children growing up in denser urban areas and those in less dense urban areas. Similar differential observations with respect to the urban environment are made for the development of independence. The normative school transition appears to have a role in some travel patterns and therefore on the development of adaptive strategies across the life course to cope with plural urban contexts. The authors further show that mobility accounts for many of the changes that occur during youth life transitions, including how mobility is a vehicle for social and spatial integration. As for parental support, the authors raise several questions about children's autonomy skills. As an obstacle to the development of autonomy in urban areas, parental support can also be considered in the family's daily life, where privileged contacts and communications are developed. In the same sense as Elsner's contribution on younger children, Depeau et al. emphasize the importance of the city's development/changes in order to be able to adapt, not a city designed for particular profiles at a specific time in the life course.
11The third contribution by Sébastien Lord, Benjamin Lamoureux and Philippe Gerber is entitled "Metropolitan mobility options and individual identities: How much households' mobility choices are determined by residential-related identities? The authors from geography and planning analyze a drastic and imposed change in the daily mobility of metropolitan workers in Greater Montréal, Quebec, Canada. These health care workers have seen their workplace relocated outside downtown area. Taking advantage of this important change experienced by all employees at the same time, the authors questioned the housing identities in an attempt to better understand the mobility choices according to the characteristics of the households and their residential environment. Several previous studies have mostly examined these dimensions separately and have rarely been able to effectively integrate the dimensions of residential identities and values. They find that sociodemographic variables, which are closely related to metropolitan functional spaces and dispersion of employment types, are only marginally significant compared to housing identity variables. These analyses suggest different avenues for research and intervention in the field of mobility. In addition, they suggest targeting lifestyles and what they mean for households and individuals to effectively develop more sustainable mobility options. It is about supporting transitions and adaptations and equipping people and their households to move along their pathways. Rather than targeting age or income variables, or other socio-economic characteristics, housing identities in their biographical logics, seemingly guiding behavioral choices, would enable urban decision-makers to better make decisions about options and supports for daily mobility.
12The fourth contribution by Florent Demoraes, Vincent Gouëset and Marc Souris is entitled “What can analysis of Space-Time of Action tell us about medium-term changes in adults’ and children’s access to place of activity? The example of Bogotá.” The authors from geography examine medium-term changes to household members’ access to place of activity, against the backdrop of urban change. They use the concept of “Space-Time of Action”, referring to the combination of all the places of work or study that individuals go to, and the time taken to reach them from home. Based on two surveys conducted at a sixteen-year interval in Bogotá, Colombia, the methodology is developed around the spatial mobilities of two profiles of individuals belonging to the same household but at two different stages of the life course: school children and working adults. The results highlight two main rationales related to time and territories in a city undergoing change in a context of functional and spatial sprawl. First, they observe an overall stability of children's access to school regardless of their place of residence, and in many cases a deterioration of the situation for working adults with a spatio-temporal gap that has increased over the period. The methodology adopted is an appropriate means of measuring the influence of contextual urban changes on the daily lives of inhabitants in relation to life cycles. The authors' work shows the relevance of including short and longer timeframes in the planning of urban spaces. Above and beyond the case study presented, the methodology could be applied in many other domains, for instance for identifying social groups experiencing inequalities in access to work, education, or health, and for analyzing the impact of a new urban infrastructure on people daily mobility. Furthermore, the contribution of Demoraes et al., like that of Lord et al., proposes to reverse the emphasis on residential spaces in urban planning and shift it to places of activity and employment. This shift seems coherent and more aligned with lifestyles and life-cycle transitions.
13The fifth contribution is by Michel Després entitled “Becoming homebound by choice and constraint: a mixed-methods look into aging and mobility transitions”. The author from sociology and planning is interested in the transition of mobility practices of some elderly people who adopt or are forced to adopt a homebound lifestyle. In this temporal perspective, the transition of the person within his or her residential environment is analyzed in a qualitative and spatial way where the transitions and bifurcations in the paths of the seniors encountered are explored in depth. It is in these past, present and future times of aging individuals that their relationships to the city are observed through the prism of their mobility capacities, which are inevitably called upon to change. This contribution places specific events and periods of biographical time in a logic of change leading the elderly individual to arbitrate different adaptations to his or her residential environment. Urban and suburban dwellers were analyzed in order to examine the contrasts and possibilities according to different urban forms. A diversity of paths leading to limited mobility in the city space, or even to immobility at home, was observed. Between chosen or undergone paths, this temporal perspective calls for a variety of responses from territories and urban stakeholders in the broad sense to help seniors maintain their autonomy. In the diversity of paths, echoing all of the contributions in this issue, whether children, adolescents or working people, lifestyles are established over time and into old age in habitats. This last contribution shows that aging populations require planning solutions that are more focused on adding adaptation options rather than applying wall-to-wall solutions for a profile of elderly people or territories.
14In this themed issue, we have contributed to both theories and methods for a better understanding and rigorous consideration of the times of individuals and the times of their life environments in research. All the contributions show that it is possible and relevant to combine in research, short and longer timeframes, be they individual or related to urban environment. The results show the added value of methodological approaches articulated in such a way as to take time into account, as well as theoretical approaches that put time into perspective and use both classical and more innovative methodologies. In this sense, it is perhaps time to bring time more deeply into the research on the city and its inhabitants in a more fluid way. That said, two perspectives can be drawn from the issue.
15The contributions of Depeau et al. and Elnesr for children, as well as that of Lord, Lamoureux, and Gerber and that of Demoraes, Gouëset, and Souris for active families, demonstrate the complexity of person-environment relationships across the lifespan, from childhood through periods of working life. This complexity is often underestimated because research often focuses on specific population profiles without placing them on a developmental continuum. Similarly, research often considers specific urban sectors or urban infrastructures, without necessarily placing them in a perspective of changes, that inevitably affect individuals, according to the household or social group to which they belong. In a way, Després’ contribution on the elderly confirms these limitations by showing that this diversity is maintained until the last stages of life, but above all that it is part of biographical continuity, including bifurcations.
16Finally, the contributions show that the analysis of mobility makes it possible to account for several types of changes or types of urban environments. It is through the transitions of people and their households from youth to adulthood, retirement and old age that it is possible to understand different types of difficulty, vulnerability or fragility in topics that go well beyond travel in urban space. Mobility, its evolution and the person-environment interactions in time and space allow in this sense to understand social, developmental or health challenges and issues. In the case of young people, Depeau et al. show, as does Elnesr's contribution, that travel is also an important spatio-temporal vector of social relations. Després' contribution even emphasizes that this remains the case in old age. The idea of the accumulation of experiences, tactics and know-how with regard to mobility seems important. We believe that this issue will contribute to opening new perspectives on research and intervention in the city.