Cities, as “primary incubators of cultural, social, and political innovations” (Barber, 2013), have been facing a constant increase in population for decades. Currently, more than 55% of the population already lives in urban areas, which is 3.5 billion people, a number projected to reach 6.7 billion by 2050 according to the United Nations, implying that 70% of the world’s population will live in urban areas (United Nations, 2018).

Since the onset of the Industrial Revolution and the expansion of the capitalist model, which prompted the massive exodus from rural to urban areas, cities have significantly increased their demographic weight (Diputació Barcelona, 2019).

In Europe, this demographic trend has accelerated compared to other regions, with 75% of the population already residing in urban areas, and Spain can be considered predominantly urban, as this percentage exceeds 80% (de la Cruz-Mera, 2019).

During the last years of the 20th century and the first two decades of the 21st century, urban spatial transformation has been framed within the Industrial and Post-Industrial phases, both governed by the capitalist system, which has resulted in a significant spatial alteration of pre-existing models. Initially, there was an intensive development in the city centre, such as the emergence of financial districts, while simultaneously opting for extensive development in the periphery to meet the demand for urban land for new industries and transportation. Subsequently, there has been a real commitment to the growth of the periphery, which includes new mono and multi-functional centres, giving rise to true urban continuums (Escolano, 2018).

This dynamic of inhabiting the planet has generated transformations at all levels: economic, social, cultural, demographic, infrastructural,technological, and environmental. Therefore, there are many projects that adopt a global perspective from a local context, studying cities and seeking to solve the problems they generate, thus improving the quality of life of their inhabitants. Some examples include the Superblocks in Barcelona, Pontevedra, and Madrid; the Melbourne 2017 - 2050 plan; the renovation of the Nordhavn district in Copenhagen; or the Merwede district in Utrecht.

The cities of the 21st century adhere to significant urban planning guidelines. Various global initiatives, such as the United Nations Conference on Housing and Sustainable Urban Development, held in 2016, commonly referred to as UN-Habitat III, outline objectives at a global scale. The Sustainable Development Goals (2015) are another crucial framework to consider, with specific emphasis on Goal 11, focusing on “Sustainable Cities and Communities.” At the European regional level, the New Charter of Athens from the European Council of Urbanists (2003) and the Urban Agenda for the European Union, ratified in Amsterdam in 2016, provide essential guidance. Additionally, in Spain, efforts towards urban planning were evident in the same year, with the development of the Spanish Urban Agenda roadmap.

In order to simplify, summarise, associate, and unify the different proposals, five general principles are proposed to interconnect the various programs:

Cities are facing a series of challenges that demand careful planning of projects and objectives, requiring swift action to prevent several of these difficulties from reaching a point of no return.

In this context, the concept of the 15-minute city (Moreno, 2023) emerged in Paris, pioneered by the scientist Carlos Moreno, director of the ETI Chair (Entrepreneurship, Territory, and Innovation), focused on the reflection of technological issues, cultural and social challenges, ecological constraints, urban spaces, and new economic and public management schemes (Chaire Entrepreneuriat Territoire Innovation, 2020).

This model of a city based on proximity and polycentrism began to see its immediate reality when in 2020 the mayor of Paris, Anne Hidalgo, included it in her electoral program. Since then, this urban policy has been widely accepted for proposing ideas contrary to petroleum urbanism, advocating for cities for their inhabitants.

One of the sources of inspiration for the design of the 15-minute city was the concept of the “living city” proposed by urbanist Jane Jacobs, whose interest in urban aspects was evident in her first book “The Death and Life of Great American Cities” (1961). In this book, she criticises the urban planning of the 1950s in the United States, a urban dynamic that has spread worldwide, promoting cities with a design opposite to the “Popular City”, that is, cities where the segmentation of uses and private vehicles have been prioritised, fostering territorial dispersion and anonymity among its citizens, which has led to social segregation and insecurity. Jane Jacobs advocates for and defends the lively and popular city where the relationship between people and public space is essential to ensure safe and complex neighbourhoods thanks to the multiplicity of networks created by various uses (Jacobs, 1961).

A valuable lesson arising from Jacobs’ thinking is a shift towards bottom-up urbanism, a planning approach based on the everyday experiences and real needs of citizens (Jacobs, 1961).

Another conviction shared by Carlos Moreno, in line with Jacobs, is the notion of “useful time.” To understand human activities, it is essential to incorporate the temporal dimension, as highlighted by Byung-Chul Han. We live in a society of work and performance, where productivity predominates (Han, 2017). This demand, which seems to turn us into slaves of time, can be reduced with “chosen mobility” or demobility, which aims to minimise wasted time during journeys by making use of the various functions of the same space.

This space-time relationship was already explored during the 1960s by the Swedish school of geography, in which Torsten Hagerstrand developed various models of spatial diffusion that included the temporal component. From these models, he concluded that an individual’s movements are conditioned by three types of constraints:

Many of the limitations proposed by Hagerstrand have disappeared with the flexidimensionality of space brought about by the hybridization between the physical and digital worlds (Campos, 2020), thus redefining social behaviour patterns. The 15-minute city considers certain technological trends that have been accelerated by COVID-19, such as telecommuting, which has eliminated many daily commutes in cities, or the rediscovery of urban spaces as a result of mobility restrictions during quarantine.

The chrono-urban policy that will design the new “City of Light” aspires to consolidate “viable” spaces where economy and ecology converge; “equitable” spaces with an economy mindful of social actions; and “livable” spaces, meaning there is a close relationship between social impact and ecology (CICIM, 2020).

To achieve these urban ideals, Carlos Moreno (2023) discusses six activities (living, working, shopping, caring, learning, and enjoying) that should be possible within a 15-minute radius from home, through walking or cycling, known as active mobility (LA Network, 2020).

In conclusion, this 15-minute city aspires to an urbanism based on the traditional Mediterranean city, characterised by continuous, dense, and well-cohesive spaces, where the mixture of uses, proximity, and a good communication network facilitate a life full of social interactions (ETSAM, 2021).

The study area is Zaragoza, the fifth-largest city in Spain by population, with 682.513 habitants in 2023 (INE, 2023). It concentrates more than 51% of the population of the Aragon region, demonstrating the clear macrocephaly of this Autonomous Community. Zaragoza stands out for its optimal location, situated in the northwest quadrant of the Iberian Peninsula (Figure 1). It is halfway between Madrid and Barcelona, the two most dynamic cities in Spain, and maintains a similar distance from Bilbao, Valencia, and Toulouse, providing a geostrategic advantage as a node in the network of the most important cities in southern Europe.

The urban structure of Zaragoza reflects the different periods that have marked its design and expansion. The city grew from the Roman historical centres, initially with working-class neighbourhoods, mainly residential, boosted by the various railway stations that revitalised the city, such as Delicias, San José, or Torrero. Later, expansion occurred through urban extensions, where the city lost compactness influenced by hygienist theory, spacing out the streets and creating meeting places for citizens in districts like Centro, Miraflores, or Miralbueno (Adiego, 1995). During the last decades, according to the classification proposed by A. Champion’s model, Zaragoza is in the stage of Suburbanization, characterised by the expansion of its periphery, based on the monumentality represented by urban projects (Ges, 2018) implemented on the urban fringe margin during the first eight years of the 21st century. This period saw excessive construction activity that ended with the financial crisis of 2007 due to the collapse of the real estate bubble (Bellet and Alonso, 2016) (Escolano et al., 2018).

The recent growth of urban space in Zaragoza has led to an increase in the urban land area, from 5,711 hectares in 2001 to 9,036 hectares in 2018 (De Miguel González, 2014). This expansion of the city of Zaragoza is characterised by residential development primarily located on the outskirts of the consolidated urban fabric. New neighbourhoods have been created, such as Valdespartera, Parque Venecia, or Arcosur. Another characteristic feature of Zaragoza’s periphery is the presence of monofunctional centres, well-connected to the city centre through ring roads, which have not only served as mere communication routes but also acted as vectors of development and urban growth. Most of the new neighbourhoods and these monofunctional centre, such as Puerto Venecia and Plaza, are adjacent to the Z-30 and Z-40 roads (De Miguel González, 2014).

For the evaluation of the 15-minute city model in the urban area of Zaragoza, four analyses are conducted to address the objectives outlined and ultimately obtain the necessary data to answer the question: “Is Zaragoza a 15-minute city?

The different geographic analyses have been conducted at the working scale that best represents each phenomenon, meaning the most appropriate for making the study object comprehensible and manageable for the observer (Reboratti, 2001) (Valenzuela, 2006). Thus, analyses, where methodologically feasible, are presented at various scales to avoid a limited view and establish relationships between elements, thereby creating a summarised and direct view of reality.

Therefore, the analysis entities that have been used are:

In this work, the cartographic component constitutes a fundamental contribution to explain the different variables under study.

Since Claudius Ptolemy laid the foundations of modern cartography in his work “Geography,” cartographic production, i.e., maps, have accompanied us for almost everything. “Not only as analytical tools, but also as a form of expressive visual art” (Pickles, and Cooke, 2015).

The paradox proposed by Jerry Brotton, “we can never know the world without a map, nor can we definitively represent it with one,” underscores the paramount importance of maps. These graphic productions “facilitate the spatial understanding of things, concepts, conditions, processes, or events concerning the human world” (Harley, et al., 1987). Thus, maps depict the spatial distribution of the various indicators studied to answer how and where the 15-minute city urban model is located in Zaragoza.

The maps have been created following the design and elaboration phases of the cartographic process proposed by (Zúñiga, 2009).

Two types of maps have been created (Figure 2): univariate maps (Complexity, Accessibility, The 15-Minute City in Zaragoza, and I’m moving house) and multivariate maps (Compactness and Intersection of Compactness with Complexity).

As previously mentioned, the content of this article undergoes a significant yet appropriate adaptation in its StoryMap version. The introduction utilises a horizontal slideshow with lateral scrolling, summarising the state of the art. The 7 slides comprising it use photographs, texts, demographic graphics, timelapse, and infographics to convey to the audience the current relevance of urban studies.

In order to generate a solid narrative structure, the final slide introduces the urban indicators that will be developed in the following sections.

The following figure is a timeline in which the different urban indicators are ordered, thus exposing the study’s objectives and the script that will be followed in the simultaneous explanation of the methodology and results.

At the same level of relevance as the Introduction, the next section is titled “15-Minute City”. In this case, the reader becomes familiar with this chrono-urbanist model by navigating through a vertical sidecar where text messages emerge.

Developed from the mathematical theory of information, the Shannon index expresses, through the calculation of H, the number of information carriers capable of contact, in terms of quantity and diversity.

For the study of urban complexity, buildings with their different uses provided by the cadastre in its .CAT files will be considered as information carriers.

Once the property uses for each of the administrative units of study have been obtained, the data is exported for the calculation of H, of which it is necessary to understand its different elements.

To measure urban accessibility to various key spaces and services in Zaragoza, a network analysis has been conducted, in which different service areas are calculated. These service areas encompass all streets accessible to each service, applying a temporal impedance of 5, 10, and 15 minutes.

To develop this analysis, it was necessary to obtain the street network of Zaragoza, acquired from QGIS using the QuickOSM plugin, selecting the Highway feature.

The street network obtained, labelled as “Highway” includes a variety of road typologies such as pedestrian streets, highways, bike lanes, etc. In conclusion, it is not the sidewalk network through which any citizen can walk, but it does serve to generate an approximation of the current service areas. This is because the alternative analysis by buffer generation is insufficient, as pedestrian mobility seldom occurs in a straight line.

Given that the concept of the 15-minute city involves active mobility, which extends beyond walking and includes cycling as a primary alternative, another network analysis has been conducted using the bike lanes for calculating service areas.

Both the bike lane network and the key structural facilities under study have been provided by the Chair of Territory, Society, and Geographic Visualization.

Before creating the Network Dataset and employing the Network Analyst extension, both the Highway (pedestrian accessibility) and bike lane (bicycle accessibility) layers were edited using the Planarize Lines tool, which divides lines at all their intersections. The following fields were included:

Once the two layers of linear entities, which function as the network, have been corrected, the Network Dataset is created to calculate the different service areas.

The maximum distance between the key structural facilities and the pedestrian accessibility network is 50 metres. Some of the facilities have been modified to meet this distance requirement.

However, for the service areas with the bike lane, a distance of 200 metres is established, which should be covered on foot (2.4 minutes on foot = 17.4 minutes maximum travel time) by the cyclist to reach their destination. In this case, no location has been edited to accurately represent facilities with poor accessibility.

Finally, since the 15-minute city concept implies sustainable accessibility to all facilities, areas with better accessibility have been calculated through vector geoprocessing. These areas are where all classes of facilities are accessible, both on foot and by bicycle. This approach aims to identify urban spaces that meet the criteria of the chrono-urbanist model.

In order to relate these first two indicators, a classification of their results has been necessary, which allows for the calculation of a common index.

For a better interpretation of the results through cartography, a dual-entry legend has been created (Figure 4). This allows for the perception of the existing relationships between the two variables, as the axis of pink tones represents the two classes of compactness (Table 3) and the blue axis repeats the process for complexity (Table 4), while also maintaining the pre-established ranges.

As a final result, the aim is to provide a clear overview of the situation in Zaragoza, considering all three indicators simultaneously. For this purpose, a 15-minute City Index has been created, classifying the different categories of the three indicators that compose it. The classification of Compactness and Complexity corresponds to Tables 3 and 4, while Accessibility has been classified based on the 5, 10, and 15-minute service areas.

As previously explained, the adaptation of this methodological section in the StoryMap is carried out jointly with the results. Thus, the “Methodology and Results” section consists of a vertical sidecar that begins by contextualising the reader in the study area. For this purpose, an animated aerial view of Zaragoza and its metropolitan area is presented alongside an expandable text highlighting the demographic and economic significance of this capital.

Next, following the timeline of the introduction, the different indicators are presented homogeneously, with the same distribution of elements: a left sidebar for methodology and presentation of results on the rest of the screen through interactive thematic mapping (option to vary the scale, unlimited scrolling, and data querying on entities).

The redundancy in the spatial layout of the content precisely aims to capture the reader’s attention. Since this section is the most interesting and presents higher complexity compared to the other sections of the StoryMap, the methodological load has been balanced to make the study more accessible to a broader audience. With its 17 maps, 8 tables, and 2 graphs, this section becomes the focal point of the narrative.

The results of compactness are divided between those obtained in the study of absolute compactness and corrected compactness.

Absolute Compactness: The results obtained from the calculation of absolute compactness clearly show that the census sections located in the city centre exhibit higher values, as the building pressure is greater there. Notable are the BHZ (Basic Health Zones) of San José Norte and Centro, Independencia, Madre Vedruna – Miraflores, Hernán Cortés, San Pablo, Delicias Sur, and Norte, all of which record absolute compactness values exceeding 6.

These results need to be qualified because this indicator is clearly influenced by the urban area of reference. In Figure 5, it can be observed that the census sections of the aforementioned BHZ have a smaller surface area compared to those further from the centre, such as Utebo, Torrero la Paz, or Miralbueno – Garrapinillos, whose values are below 1.

Therefore, Figure 5 presents compactness at two scales, allowing for a detailed observation of census sections with absolute compactness values that differ from those recorded by the corresponding BHZ. In this regard, it is worth noting the high absolute compactness values shown by the census sections in the northern parts of the Venecia and Torrero la Paz BHZ, a situation mirrored in the western sections of Las Fuentes Norte or the southern sections of Almozara.

Corrected Compactness: The result representing a correct relationship between built volume and public space for leisure falls between 10 and 50. Census sections or BHZ showing average or poor corrected compactness can be the result of two inverse situations: one where there is a large amount of public leisure space with very little built volume, as observed in the section of Parque Grande José Antonio Labordeta; or, conversely, where built volume significantly outweighs mitigating public spaces, as seen in many sections of Sagasta – Ruiseñores.

In general, the sections located on the outskirts of the city exhibit good corrected compactness due to a better balance between built volume and leisure spaces, largely owing to their open urban design with more green spaces and wide sidewalks, as observed in Valdefierro, Valdespartera – Montecanal, Casablanca, and several sections of Actur Norte and Sur.

Sections adjacent to Plaza Paraíso and Plaza España, located in the heart of the city, also demonstrate good corrected compactness, showcasing a commitment to wide sidewalks and pedestrianisation of surrounding streets. Similarly, in Madre Vedruna, the building pressure is softened by the presence of Miraflores Park, contributing to a good corrected compactness.

The values obtained with the Shannon index by building use for each block demonstrate the complexity of the city of Zaragoza. Figure 6 represents this complexity by blocks, but in order to explain the results and draw certain conclusions, the average by Basic Health Zones (Zonas Básicas de Salud) has been calculated.

Casablanca, San Pablo, Independencia, Madre Vedruna – Miraflores, and Sagasta – Ruiseñores all exhibit the highest average complexities, exceeding a value of 0.9. Conversely, some areas showing lower complexity, with values below 0.4, include Torrero – La Paz, Las Fuentes Norte, and Valdespartera – Montecanal.

This categorization by Basic Health Zones (BHZ) provides a representative summary of the actual complexity of each urban area. However, the representation by city blocks is the most reliable, as it allows for distinguishing the most and least complex blocks within each BHZ.

In this regard, the BHZ that stand out for the differences in complexity among their blocks are Utebo, Avda Cataluña, Casablanca, and Parque Goya, where a higher standard deviation is recorded, exceeding 0.6. However, in the opposite situation, that is, the BHZ where complexity maintains a more homogeneous distribution across their blocks, are Sagasta – Ruiseñores and Madre Vedruna – Miraflores, both with a standard deviation below 0.4.

In this section, the results obtained from the intersection of the compactness and complexity indicators are presented.

In Figure 7, it is evident at a glance that the blocks in the historic centre and Paseo Independencia exhibit darker colours, which indicate higher compactness and complexity. Other isolated blocks with good results can also be recognized in Arrabal, Actur Norte and Sur, and San José Norte.

The map shows a bluer tonality because the compactness index is calculated based on the two previously mentioned classes (Absolute and Corrected Compactness). Therefore, it is difficult for blocks to achieve the maximum compactness rating, which has already been represented in Figure 5 with the darkest tones.

When averaging the blocks contained within each BHZ, a reality evident in the map is confirmed, where San Pablo obtains the highest average with 5.43, followed by Independencia with 4.84, and Rebolería with a result of 4 (Low values considering the perfect situation is 9). The remaining BHZ can be classified into two groups: those with slightly higher values above 3, indicating a slight intersection of these two indices, as observed in San José Norte, Madre Vedruna – Miraflores, Actur Norte, Delicias Sur, Arrabal, and San José Centro. On the other hand, there are areas where the result is below 3, indicating a lack of overlap between compactness and complexity sought by the 15-minute city concept, once again coinciding with the BHZ on the periphery such as Torrero La Paz, Miralbueno – Garrapinillos, Parque Goya, and Valdespatera – Montecanal, which obtain the worst results.

Once the information from the different service areas to healthcare facilities, shopping establishments, educational centres, cultural spaces, and sports centres has been processed, Figure 8 shows the areas of the city with the highest sustainable accessibility for 5, 10, and 15-minute travel distances. The result for the entire population of Zaragoza is positive because 92% are located in 15-minute service areas. This percentage decreases to 80% if the maximum travel time is reduced to 10 minutes. Finally, in areas with the best accessibility, where access to all types of facilities is possible within a maximum of 5 minutes, 22% of the population of the Aragonese capital resides.

Considering the BHZ with the lowest percentage of accessible population and according to the results already outlined in the previous sections, it is the outskirts of Zaragoza that obtain the worst results. Thus, with less than 60% of its population accessible within 15-minute areas, we find Valdespartera – Montecanal (57%) and Santa Isabel (58%). The next BHZ are Parque Goya and Miralbueno, with 62% and 65% respectively.

It is also important to highlight those urban areas with high percentages of population in 5-minute service areas, or in other words, the Basic Health Zones with the best sustainable accessibility. Arrabal stands out remarkably with 70% of its population in these areas of maximum accessibility.

Following Arrabal, San José Centro, Independencia, Madre Vedruna – Miraflores, and Sagasta – Ruiseñores have population percentages close to 50%.

Finally, it is in this section where the results are discussed, allowing us to answer the question of whether Zaragoza is a 15-minute city.

As previously evidenced by the results presented, the outskirts of Zaragoza deviate from this chrono-urbanist city model. This reality is evident in Figure 9, where several blocks in these urban areas are represented in grey, indicating that they do not meet one of the requirements, such as sustainable accessibility to all types of facilities.

On the other hand, summarising the results presented from blocks to BHZ, a clear centrality of the chrono-urbanist model of the 15-minute city is observed in Zaragoza. These are the urban areas with the highest average index, such as San Pablo (12.5), Independencia (11.1), San José Norte (8.4), Rebolería (8.29), and Arrabal (8.1).

Specifying the location of the urban areas where all conditions are met, i.e., those that obtain the maximum score of 27, they are:

The bulk of Zaragoza’s population (24%) resides in areas with a rating of 6. The percentage for ratings below 6 represents 42% of the population, while in the opposite situation, i.e., the population living in areas with ratings between 6 and 27, represents 28%. Thus, as shown by the various graphs for the BHZ, there are significant differences between the areas of Zaragoza.

Analysing the data from the collaborative maps, shown in the following Figure 10, confirm the need to handle the data with caution and not draw hasty conclusions, as some results may contradict each other. For example, while Fernando el Católico is the second BHZ with the most demands for facilities, it is also the most demanded in the “I move house” map. This apparent contradiction can be explained by studying the surveyed population. If the majority of respondents are university students who spend a significant part of their day on the San Francisco campus, this can justify the relative importance given to this BHZ and consequently the “neglect” of other urban areas.