The rapid urban growth in Dakar demands innovative solutions for emerging structural and organizational challenges

The massive and rapid growth of cities, particularly Dakar, presents new structural and organizational challenges. The chaotic production and occupation of space associated with this growth create acute cultural, technical, and economic difficulties. This reality, which endangers the very development of the city, affects multiple areas of expertise, including urban planning, architecture, sociology, and demography.

In many cases, it even calls into question the analysis methods, design approaches, and intervention techniques of city managers. Additionally, urbanization in large cities is taking on new forms previously unknown (such as diffuse cities, alveolar spaces, etc.), which, due to the speed and scale of their characteristics and the lack of available resources, require entirely new approaches and intervention methodologies. This is why the City of Dakar and its strategic partners are actively seeking innovative solutions to make Dakar a resilient city.

Dakar REVE advances sustainable urban development by enhancing waste management and civic participation

The DAKAR REVE (Dakar Green Regeneration) project is funded by the Italian Agency for Development Cooperation, following the December 2019 call for «Promotion of territorial partnerships and territorial implementation of the 2030 Agenda.» The project aims to contribute to the sustainable urban development of the Dakar region in the current context of climate transition by improving urban services and civic participation related to waste management.

The multidisciplinary consortium has initiated a set of activities ranging from the construction of an organic waste collection center and the incubation of local green businesses to awareness projects in schools, training of local urban sector technicians, and the diagnosis of the entire urban system using the IMM methodology to provide strategic support for future planning initiatives. This project is a cornerstone for the success of the «Dakar Clean City» program, as well as for advocating at the local government level for the establishment of innovative public waste management and valorization channels. The project will conclude in January 2025, but some of its activities have already been completed.

The Integrated Modification Methodology (IMM) offers a data-driven, systemic approach to urban sustainability

The Integrated Modification Methodology (IMM), developed by the ABC department of the Politecnico di Milano, is a comprehensive procedure using various scientific techniques to analyze and evaluate the built environment at multiple scales. IMM is distinguished by its integrative and system-oriented approach, its focus on sustainability, its data-driven methods, and its alignment with global sustainable development goals (SDGs) The methodology involves a non-linear process that offers a systemic understanding of urban areas, proposes improvement strategies, and examines modification plans. IMM has already been applied globally in cities such as Tehran, Barcelona, Rio de Janeiro, and Milan. The methodology is structured in phases, starting with a diagnostic phase based on geospatial data, leading to the design and optimization of solutions.

The first phase involves data collection and mapping, followed by geoprocessing to enrich the information. This data, divided into four components (volumes, voids, networks, and types of uses), is then integrated to describe relevant urban dimensions, called Key Categories (KC). The KCs—namely accessibility, diversity, effectiveness, interface, permeability, porosity, and proximity—are described using a combination of maps and numerical measures. These readings allow for both a qualitative and quantitative understanding of the potential of the current urban structure in relation to specific dynamics.

The results are then further integrated to produce more synthetic representations that show the emergence of recognizable urban patterns. This process allows for the detection of the city’s weakest subsystems in terms of spatial areas and constituent elements. A meta-project then follows, defining a hierarchy of design actions to be undertaken to improve the performance of the existing urban structure. The actions identified have the advantage of being located in specific areas of the territory and can be compared with policies already implemented in the city.

Ensuring data consistency for IMM application in Dakar was challenging but essential

Geospatial data plays a crucial role in the application of IMM. However, the availability of data can vary significantly depending on the context, in terms of coverage, quality, granularity, topology, standards, and richness of attributes. Regardless of their quality, considerable effort is required to ensure consistency between local standards and those used to consolidate IMM procedures. This involves a collaborative effort between IMM experts and local points of contact to address discrepancies and ensure compatibility.

The complexity of this work is further compounded by the interwoven nature of the correspondences between the elements of the two data sets. Data collection for Dakar was particularly challenging due to the absence of a geoportal and the lack of open-source data. Several conflicting sources were integrated into a new data set. Key activities included completing information on building floors and remapping population data, with efforts to simulate missing values. The type of uses data was manually classified with the help of local staff to align with IMM concepts. Network data was primarily sourced from OpenStreetMap, while high-quality authoritative data was provided for open spaces.

This phase, known as Data Mapping, was conducted jointly by PoliMI, the City of Dakar, IAGU, and IPSIA. It should be noted that informal systems (housing, transport, activities) were not taken into account due to the difficulty of mapping them on such a large scale. However, their inclusion in the analysis is feasible if collaborative mapping campaigns are activated to determine their coherence and characteristics.

IMM analysis in Dakar highlights critical urban challenges and guides future planning strategies

The application of the Integrated Modification Methodology (IMM) to the city of Dakar has provided valuable insights into the major urban challenges facing this sub-Saharan African city. One of the most critical issues identified is the rapid urbanization and growth of informal settlements, which place considerable pressure on the city’s infrastructure and services. The analysis of the key categories «Proximity» and «Accessibility» revealed that while central areas of Dakar offer better access to points of interest and public transport, many peripheral neighborhoods suffer from low proximity and accessibility.

This highlights the need for more equitable urban development and investments in infrastructure to connect all parts of the city. The evaluation of «Diversity» also underscored the importance of promoting a mix of uses and activities to create more resilient and adaptable urban environments. The results suggest that areas with low diversity are more vulnerable to external changes and may require targeted interventions to improve their robustness. Furthermore, the analysis of the key category «Interface» revealed issues with the quality of the road network, particularly in the north-west area of Ngor and in certain municipalities such as Hann-Bel Air and Mermoz-Sacré-Cœur. This indicates the need for infrastructure upgrades and improvements in connectivity and integration within the transport system.

The evaluation of «Porosity» and «Efficiency» provided valuable insights into the relationship between built volumes and open spaces, as well as the capacity of the urban structure to accommodate growth and development. Finally, «Permeability» refers to the directness of links and the density of connections in the transport network, indicating that while the peninsula limits access, some connections exist along the coast, offering guidance for future projects. These findings can inform future planning and design strategies to create more balanced and sustainable urban environments.

The application of IMM to Dakar has demonstrated its versatility and potential as a tool for understanding and addressing the complex challenges faced by sub-Saharan African cities. The collaborative approach, involving local stakeholders and experts, was crucial in ensuring the relevance and applicability of the results to Dakar’s specific context. As the city continues its efforts to become more resilient and sustainable, the insights from the IMM diagnosis can serve as a foundation for the development of targeted interventions and the implementation of innovative solutions. The integration into the broader Dakar REVE project, which focuses on improving urban services and civic participation, further enhances the potential of this methodology to drive positive changes in the city.

Moving forward, it will be essential to continue collaborative efforts between the city of Dakar, its strategic partners, and IMM experts to refine the analysis, integrate new data, and translate the results into concrete design scenarios and policy recommendations. In doing so, Dakar can pave the way for other medium-sized cities in sub-Saharan Africa to adopt similar data-driven and holistic approaches to urban planning and development.

Strategic intervention prioritizes urban areas in Dakar for targeted development and infrastructure improvements

A collection of maps synthesizing the various Key Categories (KCs) is presented. The first map confirms the overall good performance of the North-South axis and highlights concentrations of weaker cells primarily along the coast.

The second map delves into qualitative aspects, revealing that the weakest areas from the previous map lack both uses and network components (shades of pink and purple). The central area, however, could slightly improve the Volume component (green cells). Richer insights can be obtained by closely examining this map at the local scale. The third map more clearly shows the concentration of weak cells on the West and East sides of a central core (Grand-Dakar, Biscuiterie, Sicap-Liberté) characterized by the presence of development opportunities. Finally, the last map outlines the largest concentrations of weak cells in morphological zones, which do not necessarily correspond to administrative units.

A transformation priority was then defined for the 11 zones. First, Zone No. 1 (Île de Gorée) was excluded as it is disconnected from the urban system. Next, Zones 6, 7, 8, 10, and 11 were also excluded as they are mostly within a constraint zone (airport, natural sites). Among the remaining zones, Zone 3 was identified as the most urgent due to its size, the presence of severe flood risks and other hazards, and its proximity to the city’s most performant areas. Zone 5 is significant in size, has good proximity to performant areas, and could serve as a «bridge» for neighboring weak zones.

Additionally, when considered together with Zone 3, it could help envision a horizontal axis within Dakar. Zones 2, 4, and 9 are lower priorities due to various factors such as location, size, and other transformation challenges. Among these, Zones 6 and 8 are the most interesting in terms of size and position due to the potential for creating continuity with adjacent areas. Given this, the final ranking is as follows: 3-5-2-9-4-6-8-7-11-10-1. Today, we recognize that territory is a space to be understood to grasp the dynamics taking place within it and to make the necessary decisions for its functioning. Since 2018, the city of Dakar has embarked on the process of establishing a Geographic Information System (GIS). In its ongoing quest to strengthen our GIS, the Dakar REVE project came at an opportune time.

The training provided allowed city agents to acquire new skills in processing and analyzing territorial data. Moreover, the quantity of data returned at the end of the project will not only enrich Dakar digital atlas but also the modifiable data provided, facilitating future spatial analyses. This will subsequently generate insights to help the mayor and the municipal council better guide their city policies. The IMM urban diagnostic results for Dakar highlight its general applicability, requiring specific adjustments to local characteristics. The results, aligned with visual interpretations, reinforce the arguments. The next steps include incorporating new data and creating design scenarios for the municipality, based on the same IMM diagnostic process.