Measuring Urban Vitality: how do transport infrastructure shape real estate markets ?[Mesurer la vitalité urbaine : comment les infrastructures de transport influencent-elles les marchés immobiliers ?]

Territorial development is not limited to major cities. Small and medium-sized towns also offer opportunities in terms of dynamism, infrastructure and real estate. At the same time, urban transformation promotes dynamic cities. It ensures a wide range of amenities are accessible to stakeholders. Taking the example of the "15-minute city" (Moreno, 2020), which proposes to bring together the main functions of life and the essential needs of everyone (work, home, public infrastructure, transport) within a limited perimeter. The development of major urban projects can promote the dynamism of territories and bring a certain vitality to cities and neighborhoods that until now could be considered forgotten. In this context, the future line 18 of the Grand Paris Express (GPE) raises major issues for urban planning and development. This infrastructure project goes beyond mobility issues: it profoundly redefines local dynamics, influence social and economic interactions, and transform perceptions of surrounding areas in the Parisian metropolis. Characterizing the areas impacted by the future line 18 through the concept of urban vitality is therefore an essential approach to understanding these changes. Line 18 of the GPE will pass through the national and international connections of Orly airport and the Versailles-Saclay employment area (BEVS). It represented 8% of employment in the Paris region, with 428,000 salaried jobs, and the number of jobs in the area exceeded that of employed residents by 12%. As a sign of the BEVS's attractiveness in its regional environment, 60% of executive jobs were held by people living outside the area, particularly in Paris, Hauts-de-Seine and Yvelines (INSEE, 2016). The aim of this research is to highlight the real estate opportunities that arise from the development of major urban projects. For real estate players, urban vitality is essential for understanding the specific characteristics and territorial challenges of a location. It also helps assess the feasibility and acceptance of a residential, tertiary, or hybrid project. Thus, our conceptual framework focus on the concept of territorial attractiveness; which allows us to highlight the amenities that make a territory attractive for both businesses and individuals (Cusin & Damon, 2010). Beyond territorial attractiveness, it is essential to consider territorial dynamism to help real estate players seize business opportunities. This is why we also accentuate the concept of urban vitality. Urban vitality (Jacobs, 1961) framework highlights the dynamics of territorial diversity, animation and space interconnection, offers a suitable analytical grid for assessing the potential effects of a transport infrastructure on the areas it crosses. Based on the urban vitality, the 15-minute city model (Moreno, 2020) is analysed for the six essential urban functions - living, working, shopping, keeping fit, learning and blossoming - accessible walking or by soft mobility. The study focuses on measuring the urban vitality of 1686 urban and periurban areas neighboring the GPE line 18. Exploring around two hundred databases, 67 reliable variables characterise the six urban functions. We estimate an urban vitality score for each function based on principal component analysis and a hierarchical classification of 4 clusters impacted by the future infrastructure according to their urban vitality. The four identified clusters propose a classification of territories with common territorial amenities that emphasise urban vitality to a greater or lesser extent. Then, we emphasize two territories : the Paris-Saclay educational and research hub and the Saint-Quentin Est station, characterized by a high level of tertiary vacancy. Our results offer a detailed description of the areas studied through 6 urban functions. We therefore analyse the territorial specificities of these areas to highlight the development opportunities in terms of real estate. From an empirical point of view, we propose a vitality score based on different territorial variables. This score is primarily intended for stakeholders to help them in their decision-making for the development of real estate projects. This score offers a straightforward and comprehensive overview of territorial real estate opportunities. The urban vitality score is considered relevant and representative for local development, it could become a key tool for identifying investment opportunities, promoting projects or anticipating real estate market needs.