3.1. Project Identification Stage
Born as a result of methodological research and study area selection, the core problem that best describes the symptoms that afflict Pikine Est is the negative influence of urban lacks and inadequacies in LQIs for its citizens. This main problem was first studied through a SWOT Analysis, which defines project strategies that work together with the group’s strengths and create plans of action to mitigate weaknesses and remedy threats. It is worth recalling that strengths and weaknesses are internal within the target group, while opportunities and threats constitute external factors. The analyses suggest that it would be useful to take advantage of Pikine’s cultural mix in order to best merge rural tradition with urban innovation. This could later become a strategy to create a sense of social well-being through the diffusion of the project by its own inhabitants, and it could enrich following decision-making stages with stakeholders. On the other hand, through this methodological tool, it was also possible to conclude that the project must seek to remedy a culturally marked gender gap, part of the target group’s weaknesses.
Afterwards, a problem tree structured the core problem. By addressing the causes that generate it, hypothetically, the project was able to revert these situations, and eventually mold the problem into a scenario, examined later in the objective tree. Causes for the core problem identified include high population density in an area with scarce common/green areas, gaps in educational basis for the youth (such as illiteracy and scholar abandon), and inadequate spatial conditions for cultural diffusion and teaching. Naturally, the effect of the core problem itself is the high amount of people opting for irregular migration.
The objective tree integrated what the project in its entirety must comprise and showcased the ideal conditions that need to exist in order to arrive at an ideal scenario. Causes were reverted and project objectives were obtained as outputs. In this case, these objectives included assigning areas for densification as well as common areas, providing schools with the lacking infrastructures (in the area, many lack proper canteens and sanitary installations [32
]), and creating spaces for cultural diffusion.
The first set of indicators is shown in Table 1
. Each aspect contains macro indicators commonly used to address life quality. This study presents only those which are pertinent to the study area, as LQIs are extensive and vary in their applicability according to their context [4
]. Indicators were selected within each macro group under the same criteria.
The most relevant indicators were filtered based on specific criteria (i.e., data availability, pertinence to the study area and target group, stage in which they are assessed, and time required for their assessment [26
]) and extracted from the first list of indicators (Table 1
). The final KPIs were population density, waste containers’ average saturation rates, public transportation service performance, recharge of groundwater, and literacy facility capacities, as seen in Table 2
Among the initially selected indicators, 11 were suppressed due to scarce data availability, 10 due to the stage of assessment (removing those that may only be verified at a project monitoring stage), 7 due to the extensive time requirements for calculation, and 1 due to the non-pertinence to the study area and target group as, as explained in Section 2.2
, different services have adequate coverage, availability, and proximity to reach most of the population of Pikine Est.
Incremental indicators considered here affect the study area today, but they are also likely to be applicable in other African contexts assessment tools for quality of life [46
]. For instance, water management is a tendential issue in developing communities due to lack of sanitation networks and proper water drainage when it comes to coastal cities and constructions over soil-sealed land. As examined in Section 2.2
, literacy is another key element to address, usually accompanied by gender gaps, where men have higher literacy rates than women, reducing the equity in opportunities [23
]. Biodiversity may naturally involve strategies more specific to each context, changing according to the environment of each developing community, although its indicators may still be applicable in different cases. Reduction of biodiversity may affect local small and large economies [47
]. Assessment tools and strategies to promote heritage should also be included, as increasing the common sense of belonging is a proper way to sponsor economic and social growth within the community by its own inhabitants [45
Additionally, it is imperative to clarify the concept of “artealization” introduced by [45
], which relates to the different ways in which citizens appropriate a public space with a specific heritage connotation. This is a pertinent concept to introduce in urban design, incentivizing creativity in the usage of public spaces through visual arts, music, literature, and performances [45
3.2. Project Formulation Stage
Research, discussions, indicators, and strategies take shape in urban interventions, rooted in smaller-scale (incremental) actions which lead to cyclic progress toward a large-scale change in favor of the community. As we were aware of the limitations, mostly in the financial aspect, that such interventions might face in this spatial context, they were separated into three scenarios. Each intervention scenario proposed or adapted strategies around one of the lacking branches of urban life identified in Section 2.2
: transportation, collective spaces, and service facilities. By identifying these macro-areas of intervention to focus on, future scenarios were composed of punctual strategies that point toward the improvement of a wide-scale element or activity within the urban grid of the study area. It is therefore natural that these macro-areas or branches vary between contexts. However, their individuation is of the essence at a project formulation stage in developing community scenarios to assist in project feasibility.
The project strategies were the result of the method’s application in the study area. An adequate application of an incremental project strategy should point towards short term improvement of conditions through inhabitant participation and involvement using low resources. For instance, large infrastructural solutions to the water management issue in Pikine Est such as those proposed in [48
] cannot be considered as incremental strategies. However, institution strengthening and community awareness on the matter [48
] may be conceived as incremental actions, promoting consciousness for better behaviors using few financial resources.
As stated previously, strategies are bound to vary under different conditions, not denying however a possible replicability amongst them. It is essential to clarify that the division of scenarios does not mean that strategies cannot intersect in more than one scenario; it simply means that the chosen strategy set works best when applied in its corresponding scenario. In fact, one of the main reasons to conduct a project evaluation and assessment through MCA methods is interest in determining which are the best strategies to apply in the study area. These tools and methods should be used as means of recognition of a scenario’s incremental factor and effective LQI improvement, assessed in terms of each study’s selected KPIs (presented in this study in Table 2
To achieve the goal of creating opportunities for youth and through incremental urbanism principles, the project scenarios mixed strategies as follows (These explanations can be compared to the graphic material included in the Appendix A
Scenario 1. Public Transport as main axis: Parting from a core intervention consisting of the displacement of the nearby Petit Train Bleu station to a closer point in the area, this scenario foresees the revitalization of pedestrian and vehicular roads connected to the station’s new location. Today, many small-scale businesses bloom within the neighborhood, but the lack of proper infrastructure is their most common challenge. As a result, all three project scenarios propose the application of modular spaces built from economic yet durable materials in efforts to optimize and structure these commercial activities and to be placed along these “commercial axes”. These activities currently go from fruit sale stands to furniture selling kiosks. A similar discourse regarding the creation of “revitalized commercial axes” is applied when determining the location of new bus stops. This strategy is applicable to the following two scenarios, where stops are built using local materials (e.g., wood, recycled rubber from tires). In this way, bus stops can also reduce costs, while allowing for easy dismantling should it be required at a project operational/monitoring stage. At a cultural level, this scenario foresees a secondary use of Cinema Awa as a cultural hub and the requalification of the existing Maison de la Femme as an alphabetization facility with courses held by women in the community.
Finally, each scenario tests different options for densification. Habitational typologies are taken from “50 Urban Blocks” [49
]. These blocks include floor area ratios and coverages for each suggested volume. For all three scenarios, they are chosen by balancing the number of square meters they occupy with the quantity of space available for densification, composed by the area currently deemed as “irregularly occupied” [50
] and additional blocks with poor states of housing consolidation. Once chosen, their calculations and volumes are adapted when needed in order to keep them at a maximum height of five floors to avoid disruption in the urban landscape.
Scenario 2. Collective Spaces as main axis: This scenario alternative suggests that well-kept spaces with a wide diversity of trees would play a key role as a strategy to attract higher flows of people. From this initial premise, other services are located in proximity to “natural corridors”, designed to connect the study area with nearby natural bodies, such as the wetland to the north. Following the guidelines for feasibility from similar projects [51
], these corridors will be reforested with lemon, mango, moringa, and jatropha trees. Responding to the consequent increase of shadowing (and therefore the creation of darker areas prone to insecurity), these spaces in the project will also incorporate lower tier light posts. As a secondary strategy, a new medical center is proposed on a plot where there is currently a gas station (abundant in the area), allowing the possibility to complement this section of green axis with commercial activities and exterior sale stands. The housing typology selected for this scenario prioritizes the creation of shared spaces within urban blocks. This proposes spaces that are a middle ground between private and collective property, meaning they are of common responsibility, hoping to begin the conscientization process at a smaller scale by slightly altering ways of inhabiting. Finally, at a cultural level, this scenario proposes using walls surrounding the soccer field to display famous personalities from Senegalese history, focusing on the relevance of heritage.
Scenario 3. Facilities as Main Axis: The main action featured here consists of joining Marché Syndicat with Marché Waxinaan and transforming them into linear markets. The spaces they currently occupy will then host the scenario’s core structures: new medical and cultural centers will be built in the plot occupied by Syndicat, while Waxinaan will be moved to leave space for a workshop near the school grounds, which will supply the local educational facilities with the furniture they currently lack, according to the document from the Pikine Est municipality. Both activities are also addressed to increase the number of jobs on-site.
For each scenario, separate waste containers are placed in the inner spaces of the designated blocks, keeping them away from the sight of local passersby. Among the investment costs to be considered, it would be advised to include costs for information, covering the expenses required to let citizens know which days each waste container would be collected and how to separate waste. From the literature and research, it is possible to know there is a likelihood of finding discarded tire rubber in the study area, therefore allowing its reuse, in this case, as pavement material, providing an alternative to asphalt sidewalks and increasing ground permeability this way. Other strategies were considered to combat sea level rising and flooding events. These, however, were not included in the project formulation stage because, according to research, an optimal solution would require large-scale infrastructure costs, not pertaining to the Pikine Est municipality. These strategies can be found in the flood prevention and drainage project [48
3.3. Project Evaluation Stage
After conducting assessment feasibility studies as selection filters, the final KPIs used for the project evaluation are population density, waste containers’ average saturation rates, public transportation service performance, recharging of groundwater, and literacy facility capacities. As part of the impact assessment methodological tool, these KPIs will be briefly explained below.
Population density (habitants/km2): Estimates future demographic change brought along with each habitational typology proposed by the urban scenarios, establishing a ratio between the number of inhabitants within a surface area. High values are preferred for this KPI, under the concept of stimulating care for collective spaces proposed in each habitational typology. This KPI is also highly relevant, as its results for each scenario are used to calculate other following KPIs.
Waste container average saturation rate (days): Estimates how often waste collection containers reach their maximum capacity. A service coverage ratio is established, making it possible to use population density calculation results to foresee the number of people using each container site. Data collected from Diawara [11
] offers a daily amount of waste per inhabitant per household waste material. Using the material densities of each, it is then possible to calculate an average saturation rate. High-value results are preferred, suggesting fewer weekly trips needed for waste collection vehicles.
Public transportation service performance (%): Foresees the coverage public transport will offer for the community. It is calculated by obtaining the percentage of people living within a 400 m radius from any public transport station within the study area [25
]. This category includes both bus and railway transport systems. High values are preferred, indicating better performance.
Recharge of groundwater (ground permeability) (%): Strategies to increase groundwater absorption as a response to flooding events include recycled rubber pavements as well as the creation and expansion of green areas. With each material’s permeability coefficient, it is possible to calculate the new overall ground permeability percentages. Higher values are preferred, as higher ground permeability may mean better flood control.
Literacy facility capacities (people): Calculates the maximum number of people that may simultaneously occupy the alphabetization structures. Obtained by dividing the effectively useful area of each facility, accounting for 15% of each for technical rooms and circulation, by the minimum area required for each occupant [52
]. Higher values are considered positive, meaning that more people can benefit from the facilities at once.
The performance matrix presented in Table 3
displays the resulting values for each KPI following their assessment. For the KPIs used, a higher value is considered as a positive and desired value, whilst a lower value is negative.
Initial results could suggest a triumph of Scenario 1, excelling at two categories and failing only in one. However, there is no further support for this decision, as preference has not been established among KPIs. To counterbalance the limitation of not being able to contact all project stakeholders and establish said preference, Visual PROMETHEE was used as a decision-making software classified as an outranking method. The PROMETHEE method for this software began with the insertion of KPI assessment results. By assigning a preference for each result (indicating whether the desired value is the lowest or the highest), giving each a “quantitative” or “qualitative” assignation (all KPIs are quantitative for this study), and selecting a preference function (calculation method to determine how much is one alternative preferred over another), an Impact Matrix as created within the software.
For this study, the PROMETHEE method with “Linear” and “V-Shape” functions were assumed to be tailored to the nature of the criteria, as they are the most appropriate ones to treat quantitative indicators such as those employed to assess the project scenarios [19
]. The remaining functions work best with qualitative information. The main difference between Linear and V-Shape is whether an indifference is accounted for or not, respectively. Indifferences (Q in PROMETHEE) are mostly applied when indicator results are widely different one from another, as they express which is the minimum value that a decision-maker would find negligible. Preferences (P), on the other hand, stand for a value that would weigh on the chosen scenario. The preference function assistant featured in Visual PROMETHEE helps determine preferences and indifferences (when applied) in the absence of stakeholders or decision-makers. In the case of preferences, it does so by inserting the value of the difference between the highest and the lowest indicator value. For indifferences, it uses the standard deviation between the differences. Once the proper preference functions have been selected, Visual PROMETHEE can calculate the preference index, which represents the intensity of preference of one KPI over another, taking into account the weights assigned to each. For this study, all KPIs were assigned with equal weights, for this is a decision to be discussed extensively with project stakeholders.
Finally, the preference index was used in Visual PROMETHEE to calculate outranking flows, divided into two kinds: leaving flows (i.e., the “positive” ranking for each scenario, represented as “Phi+“ in Table 4
) and entering flows (i.e., the “negative” ranking for each scenario, represented as “Phi−“ in Table 4
). The net flow was conceived as the determining outranking result, obtained by the difference between outranking flows. Results following MCA application are shown in Table 4
Remarkably, these results show the radical triumph of Scenario 2, focused on strategies for Collective Spaces, over the other two alternatives. It is of the essence to remark that this decision is the result of evaluation including only five KPIs and is not under any circumstance implying that it would be the most successful of all interventions if they were to be implemented. As mentioned before, this evaluation shows the best combination of strategies applied in the project formulation stage. Nonetheless, it is possible to observe how, out of all five KPIs tested, Scenario 2 was first in only one (waste container saturation rate), while the other two scenarios each ranked best in two categories each. This proves the usefulness of PROMETHEE methods in the assessment of incremental urban planning project strategies, as the results displayed in Table 3
do not act as a proper evaluation able to provide support in choosing an ideal scenario. Graphic material produced to represent Scenario 2 proposals is shown in Figure 6
, Figure 7
and Figure 8
. Proposals for Scenario 1 and Scenario 3 are included in the Appendix A
Result examination cannot be limited only to the highest-ranking scenario, but must also include the lowest. Doing this brings attention to the outranking results of Scenario 3, obtaining the best KPI results within the incremental aspect KPIs (facility capacity and ground permeability: see Table 3
) but ranking last after conducting MCA. Although this might seem contradictory to the study’s claims at first, it is mainly due to weight assignation. Initially, all LQI aspects included in this study were assigned with equal weights; PROMETHEE makes no distinction amongst them. Therefore, scenario 3 ranks last despite excelling in the incremental aspect.
The proper way to decide weight values for aspects or KPIs is through stakeholder discussion. For example, one weight assignation criterion could be to apply a larger weight to the population density KPI, as it is used to calculate the other two KPIs. In this case, however, a sensitivity analysis was implemented, using the walking weights tool, which shows dynamically the effects of altering the weights for each KPI. The weights were initially set at equal percentages and show the moment in which scenario 3 outranks another by assigning larger weights to KPIs in the incremental aspect.
Moreover, the results were examined through the web graph tool. These graphs allow comparing KPI assessment results in one same graph despite the difference in their measuring units. They also evidence a project scenario’s strengths and weaknesses. Web graphs for each scenario are shown in Figure 9
As seen from the charts, all three project scenarios are very distant from one another, at least under the selected criteria. This shows that the model created is effective when confronting different project alternatives that excel in different fields and placing them on the same level of comparison.
The scenarios formulated here are not to be taken as the final results of an incremental Pikine Est. As the definition exposed here says, these scenarios would be offering the initial steps to unleash incremental growth processes within the municipality, and they should be constantly monitored and assessed. Here lies the main premise for the requirements of future developments. A future inclusion and calculation of other KPIs will continuously enrich the results of this project, up to a point of determining which is the ultimate combination of strategies that compose the best scenario for incremental development.