**1. Introduction**

Currently, planet Earth and all its inhabitants are living during the key moment to stop climate change. According to UN-Habitat [1], cities are responsible for more than 60% of the world's greenhouse emissions and are thus an important part of the problem. Nevertheless, the authors of the present paper believe that cities are also the solution, but only if immediate and effective actions are taken within them.

Urban planners and decision-makers have been exploring new ways to reconfigure and build cities, with the objective of making more livable, safe, affordable, environmentally friendly and sustainable urban realms. However, the rate of change is not fast enough to meet the needs to stop climate change. Certain cities are advancing faster than others; therefore, the current project has decided to analyse to what extent the City of Monterrey, Mexico, is transforming to become a more accessible environment for its inhabitants by using sustainable modes of transport to provide access to its main destinations.

Monterrey is one of the largest cities in Mexico, with an area of 324.8 km<sup>2</sup> and 1,142,994 inhabitants according to the 2020 census of the National Statistics and Geography Institute (INEGI, by its acronym in Spanish). This city shares its urban environment and transportation infrastructure with eighteen municipalities, which comprise the Monterrey Metropolitan Zone (MMZ): Abasolo, Apodaca, Cadereyta Jiménez, El Carmen, Ciénega de Flores, García, San Pedro Garza García, General Escobedo, General Zuazua, Guadalupe, Juárez, Monterrey, Pesquería, Salinas Victoria, San Nicolás de los Garza, Hidalgo, Santa Catarina and Santiago. According to INEGI, the population of the MMZ is 5,341,177 inhabitants within a 7657 km<sup>2</sup> area.

Even though Monterrey is one of the wealthiest cities in Mexico, due to its industrial workforce and productivity, it faces several environmental and urban mobility challenges [2]. Monterrey has been previously identified as the second-most-polluted city in Latin America and holds the ninth place amongs<sup>t</sup> most polluted cities in the world [3]. This pollution problem is produced by carbon and co-pollutant emissions from both traffic and industry. The city's urban mobility statistics have shown an increasing trend in the number of vehicles, while the use of public transportation has been decreasing [2]. Public transportation in the MMZ lacks security, is expensive and is often described as timely inefficient, making private vehicles the preferred choice for inhabitants [3].

The weather in Monterrey can also affect the citizens' willingness to use certain modes of transportation, such as walking and bicycles. Temperatures in the MMZ can reach extremely high values surpassing 35 ◦C during the summer months [4,5].

According to the Sustainable Urban Mobility Program for the Monterrey Metropolitan Area 2020 (PIMUS, by its acronym in Spanish), the mode share (the percentage of travellers using a particular type of transportation) is 46% for cars, 20% for public transport, 19% for walking, 6% for transport network companies (TNCs) and taxis, 5% for institutional transportation, 2% for school transport, 0.8% for bicycles and 0.3% others. Furthermore, the travel purposes are 44% work, 18% education, 14% shopping, 12% accompany or picking up someone, 4% recreation, 3% health and 5% other [6].

The elevated number of vehicles in the city, together with an inefficient urban design, results in traffic congestions, which at the same time contribute to an increase in carbon and co-pollutant emissions due to the repetitive motor starts and stops [7]. This worsens Monterrey's pollution. Citizens from the MMZ also suffer from accessibility disparity when it comes to their mobility options, which is related to socio-economic factors. The higher the income, the more options the citizens have for travelling within the city and to access certain opportunities. This disparity is more evident in such a vehicle-oriented urban morphology [3].

There have been different efforts and projects to improve urban accessibility within the MMZ; an example is Distrito Tec, which is a project led by the Instituto Tecnológico de Monterrey (ITESM) university in collaboration with the community in the vicinity of the campus and local authorities. It aims to improve the urban environment near the university campus for citizens and campus users. This project is one of the City Improvement Districts (CIDs) implemented in Monterrey, emerging as proposals of urban regeneration to increase citizen engagemen<sup>t</sup> at strategic points of the MMZ. Figure 1 shows the facilities of the ITESM Monterrey Campus, allotments and green areas within Distrito Tec.

This particular CID is an area of 452 hectares located at the south of Monterrey City. It has a population of 26,333 inhabitants and comprises 24 surrounding neighbourhoods of the university [8]. Distrito Tec is of special interest to investors and local property owners due to the high demand of services (food, lodging, leisure, entertainment, among others) required by the community of students, professors and collaborators at Tecnológico de Monterrey. This dynamic environment results from the proximity and integration of this polygon to the university, and it is an interesting small-scale representation of an urban environment [9].

**Figure 1.** Urban representation of Distrito Tec, in the City of Monterrey.

In response to the current increasing mobility problems in the MMZ, the present study proposes the analysis of urban accessibility using the Urban Accessibility Computer (UrMoAC) software developed by the German Aerospace Centre (DLR) [10]. The analysis was performed at two scales: (i) the metropolitan level (entire MMZ) and (ii) the local level, using the Distrito Tec Area (neighbourhoods in the vicinity of the Tecnológico de Monterrey university campus). Both scales have the objective to measure accessibility to destinations that most people frequently visit: schools, main employment centres, supermarkets and hospitals. Nevertheless, each scale of analysis has a specific scope and methodology to evaluate accessibility, as will be explained in Section 2.

It is important to mention that the whole social, economic and, to a certain extent, political structure of the city behaves as a metropolitan area, despite the actual political divisions. Therefore, it is key to comprehend the urban needs at the different scales to develop public policies and interventions that respond to specific issues.

In contrast to traditional urban planning theories and procedures, taking an approach from urban accessibility has been demonstrated to have an incredible potential to better understand the systemic and complex nature of cities [11]. According to [12], accessibility can be defined as the "extent to which the land use-transport system enables (groups of) individuals or goods to reach activities or destinations by means of (combination of) transport mode(s)". Furthermore, it has been argued that accessibility consists of four components: (I) transport, (II) land use, (III) temporal and (IV) individual [12]. Accessibility concentrates on studying and evaluating how people access, or not, the different opportunities (destinations) of the urban realm, by taking into account the distributions of activity locations and the available transport modes within a given area.

It is important to mention that there are certain variables that affect the peoples' behaviour when accessing opportunities in the city, which go beyond the availability of activity locations and transport alternatives. These variables can be related to social preference (e.g., a family prefers one school over another), demographic (group ages of the population in a specific area), entitlement to health services (whether a person has the right to receive attention at a specific hospital or not), or level of service of the opportunities (this has to do with opening hours, capacity and type of service provided), among others.

It is crucial to fully analyse these variables before suggesting or making any interventions in the land use or mobility network of a given area, as they drastically affect the level of accessibility for the local population. Nevertheless, to do so goes beyond the scope of work of the current research project, which aims to provide a preliminary diagnosis of urban accessibility at the metropolitan and local level and relate it, only for the local level, to the 15 minutes city planning approach.

"La ville du quart d'heure" or 15 minutes city is an urban concept developed by Carlos Moreno where he imagines a city where every urban dweller can access her/his daily necessities within a maximum of 15 min of travel time by foot or bicycle [13]. The 15 minutes city implies an urban shift from car-oriented cities to proximity-based cities, upon the idea that "quality of urban life is inversely proportional to the amount of time invested in transportation" [13].

In this sense, the 15 minutes city concept emphasizes urban planning at the local (neighbourhood) level and concentrates on promoting accessibility rather than mobility. The focus is on diversifying land use to guarantee that every part of the city has enough green space, housing, public services, recreation areas, and jobs, at the local level, instead of developing more or higher capacity transport networks. Micromobility plays a key role in 15 minutes cities, as it promotes people's ability to access all local opportunities by walking or by using a bicycle. Hence, there is a special interest in creating open streets that foster activity in the public space and make walking and cycling safe and comfortable [13].

As a result of recent planning trends such as the 15 minutes city and a transition of transport modes from vehicles to active mobility (such as walking, cycling, etc.), accessibility has taken a spotlight in the planning paradigm by encouraging ideas such as mobilising people rather than motorised vehicles; creating access, not mobility; and thinking first at the local level [14].

To analyse to what extent Mexican cities are prepared to become accessible or 15 minutes cities and have a safe, comfortable, and realistic transition to active mobility, it is necessary to understand the transport modes and the availability of activity locations, as well as cultural, economic, political and social factors that may promote or oppose such transformation. Hence, the use of urban accessibility measures represents an adequate approach to comprehend travel times and distances and their implications in a social, economic, and environmental dimension. The results represent a key input to detect accessibility issues and develop solutions for them. They also are usable knowledge that can be easily transmitted to the local population to socialise and cocreate interventions, projects, and public policies that can transform the local environment into a safer, more livable, affordable, accessible and sustainable place.

Finally, it must be said that large Latin American cities have specific socio-economic and spatial characteristics that make them very different from cities of similar sizes in other parts of the world [15]. Recognising and working with these specific characteristics has been an important part of the development of the project, to sugges<sup>t</sup> and reach results that are relevant and tailor-made for the nature and context of the MMZ and Distrito Tec.

#### **2. Materials and Methods**
