New Urbanism: Measuring Walkability, Mixed-Uses and Green Spaces. Methodology Report.
Edited by Gonzalo Sanchez Garcia
Contents 1. Literature review. 2. Research Method. 3. Techniques. 4. Research Questions. 5. Summary of results. 6. Conclusion. References.
New urbanism: Measuring Walkability, Green Spaces, and Mixed-Uses. The socio-spatial segregation caused by gated communities in Bogota, Colombia and how New urbanism tools might mitigate this situation, it has been a hypothesis extensively explored in my Studio B and C project. The research method has been focused on a comparative analysis of selected gated enclaves (Pablo VI, La Felicidad and Ciudadela Colsubsidio) and New urbanism concepts such as walkability, mixed-uses and green spaces. The aim here was understand in what extend these concepts are present or not, what is their spatial configuration, and how the results of the analysis might inspire further developments based on New Urbanism. In this regard, the following work reports the plan for this investigation, including the works and references consulted, the proposed method, research questions, and the summary results.
1. Literature review. The first stage aimed to provide a context and definition of selected variables from New Urbanism as key components for good neighbourhood design. The work started with a brief review literature regarding the concept of walkability, mixed-uses and green spaces. Likewise, this included a brief outline of selected indicators, and how they have been put into practice on selective cases. Walkability The concept of walkability encompasses the opportunity for walking and social contacts in the cities. it supports all modes of transport and bringing benefits to the economy, environment and human health. Rafiemanzelata, et al. (2016), for instance, stances that walking at least thirty minutes per day can reduce the body weight, the possibility of heart diseases and overweight. Likewise, walking can mitigate the levels of pollution within the neighbourhoods by reducing the use of cars and encouraging affordable transportation system (Lo, 2009). This in turn might increase the number of visitors and local businesses such as retail markets, entertainment and other local services (Ryan, 2003). In this context, walking is an activity-friendly that can support urban planning of neighbourhoods by considering these and other benefits. The existing literature reports several indicators to measure the walkability of a neighbourhood including some aspects that can only be measured subjectively such as the sense of security and road-scape richness. The density of nodes and intersections, for instance, are used for measuring the connectivity and number of pedestrian routes available in the site. The studies suggest that well-connected neighbourhoods are expressed by a minimum value of 0.4 node per hectare and an average block length between 90 to 120 m (Gori, Nigro and Petrelli, 2014). Similarly, the quality of pedestrian infrastructure can be assessed by identifying roads with poor spatial
conditions, non-functional values, traffic volumes, and streets feasible for walking with suitable sidewalk width, planting edges and urban furniture. Lastly, the indicator of proximity establishes the grade of pedestrian coverage within an airline buffer of 500 mts in relation with a specific destination. This measure is known as the pedestrian catchment area (PCA), where a PCA value between 50% to 60% is considered appropriate for walking. By contrast, a value lower than 30% might be pondered as non-walkable area (See figure N. 3). Hence, the walkability index might be calculated from several indicators related to road network.
Figure 1. PCA computation where: (a) IA and (b) PA. Source: Gori, Nigro and Petrelli, 2014.
Land Use Mix The Mixed-uses are defined as the spatial intensity of different land-use types such as housing and recreation within a specific place to promote activities in the public realm (Manaugh and Kreider, 2013). An example of this is Laguna West, California in The United States. This is a successful community, where bars, shops, and restaurants proliferate in the town. The combinations of commercial and residential uses designed in Laguna West, exemplifies how retail spaces can increase social diversity and business opportunities for local communities (Jacobs et al, 1993). In this regard, Sung and Lee (2015) state that there is a positive relationship between the concentration of land uses and mobility. It means that the time of pedestrian journeys to residence services can be reduced, as long as a variety of uses are available in the neighbourhood. Thus, they estimated that a full range of uses such as housing, school, work, civic, and commercial shops proximity could facilitate walking distances and social interaction.
The selected indicators for measuring mixed-uses are summarized in land-uses accessibility, intensity, and spatial configuration. The first measure addresses the availability of land uses and access opportunities for citizens through different modes of transportation. Previous studies established that the availability of commercial or other uses within a range of 300 feet from a particular dwelling, might enhance the opportunity of walking or biking (Cervero, 1996). The second indicator attempts to quantify the land use types and the grade of mixed-uses within a determined urban area. This can be calculated by using an entropy formula based on Shannon & Weaver, 1949 (see figure.2), where a land-mix grade of 1 is considered the maximum mix value, and a value of 0 indicates the existence of single land use and thus less walkable. The spatial configuration describes the physical qualities of land use types and how they are distributed within the place, including building types and their architectural richness (Bentley et al, 1985). The aim here is to survey the perception and interpretation of the place from view of users and owners. Thus, these indicators might provide a mechanism for understating the nature and organization of land uses within a specific area.
Figure 2. LUM: Land Use Mix – formula: “Where LUM is the land-use mix score, pi is the proportion of the neighbourhood covered by the land use i against the summed area for land-use categories of interest, and n is the number of land-use categories of interest.” Source: Mavoa et al., 2018.
Green spaces. Greenspace is usually considered as an open area, covered of grass and other forms of vegetation such as trees and flowers, within an urban context (Taylor and Hochuli, 2017). Greenspaces represent greater benefits for the urban ecosystem expressed into a wide range of landscapes such as parks, gardens, playing fields, cemeteries, green corridors, and ecological reserves (Taylor and Hochuli, 2017). For example, some studies have shown that citizens who use these spaces have better relationships with their neighbours and a greater sense of place (Jansson,2014). Likewise, high-quality green spaces can reduce local crime and anti-social behaviours by encouraging social interaction and a steady flow of visitors or residents. Regarding ecological benefits, the existing literature advises that parks might provide a habitat for wildlife, improving the air quality, and creating permeable areas for stormwater collection. Lastly, some economic advantages comprise the attraction of new business and employment, increasing of property values, and local taxes on behalf of smaller events that take place in public parks (Jansson,2014).
Accordingly, green spaces can be beneficial for communities by adding aesthetic qualities to the build environment. The proposed indicators in this section comprise the evaluation of green-spaces within three categories: provision, quality, and spatial distribution. To begin with, as the name suggests, green-space provision captures all available green areas and relates them to the total of inhabitants of place. In this regard, The World Health Organization suggests the availability of a minimum of 9 m2 of green space per inhabitant with an ideal value of 50 m2 per capita (Russo and Cirella, 2018). The second indicator attempts to assess the physical attributes of greenspaces such as vegetation cover, urban furniture, leisure facilities, and the existence of pollutants. These distinctions can affect the public activity and indirect health benefits of green spaces from activities such as doing exercise or walking (Jansson,2014). Likewise, the spatial distribution is especially relevant to identify if green-spaces are equally accessible or not by users. This measure serves to identify their size variation and how this can limit public activity. For example, whereas smaller green spaces may be suitable for child’s play, larger areas may support sporting activities for adults and teenagers. (Annerstedt van den Bosch et al., 2016). Thus, these indicators can measure green-spaces from several perspectives.
2. Research method The research method was focused on a theoretical technique based on previews works, case studies, and data analysis of both qualitative and quantitative. This helped to provide a better understanding of the concepts studied and assessing how they react within selected case studies. The method comprised five stages described below. Stage one. Definition of concepts and indicators. A brief literature survey was required to clarify the meaning and relevance of walkability, mixed-uses and green spaces for urban settlements within context of New urbanism. Likewise, several indicators were extract from different sources as they help provide values and deductions easy to compare and analyse. This content was certainly discussed in the first section of this work. Stage two. Cases studies. The neighbourhoods selected for this work were “La Felicidad”, “Ciudadela Colsubisidio”, and “Pablo VI”. These examples represent the growth pattern of gated enclaves in Bogota from last 30 years, including their multiple variations in terms of form, uses and densities. The data were derived from Planning Department (In Spanish Secretaria Distital de Planeacion) and other supported online sources. Stage three. Analytical process. The proposed indicators were tested for an aerial buffer 500mt (8 hectare), located around the geographic centre of each case study. The purpose was to measure the grade of walkability, mixed-uses and green spaces, characterise their spatial quality and identify positive and negative trends.
Stage four. Results. Through a comparative analysis, this stage sums up the results of the analysis into a list of deductions, comparisons and individual findings for each case of study. Stage Five. Conclusions. The final stage of the work addressed the drawing out of some conclusions and a preliminary agenda of design implications for my further studio C project. Likewise, this looked for responding the research questions formulated for this study.
3. Techniques Some techniques and tools were used to apply the proposed indicators. Firstly, to make the data comparable and easy to read, a matrix was designed for guiding analysis and the research structure. (see figure 4) This was valuable for organizing information, delivering outcomes, and conclusions. Likewise, all data were integrated with Geographical information system (GIS) to develop precise measures and detailed 2d graphs. A cadastral layer of case studies was used for this purpose, and observational data such as photographs, were also analysed to validate GIS measures and the qualitative indicators. Additionally, a spatial network analyses was implemented to assess the grade of connectivity by using the software known as “Depthmap X” (UCL, 2016). Hence, these techniques and tools described in this section can help to carry out the suggested method. Pablo VI
Figure 3. Depthmap: connectivity maps. Source: Author.
La Felicidad
Ciudadela Colsubsidio
Figure 4. Analysis Matrix Source: Author.
4. Research questions 1. What extend the new urbanism qualities such as walkability, affordable green spaces and mixeduses are present or not in the gated communities of “Pablo VI”, “La Felicidad” and “Ciudadela Colsubsidio” in Bogota? 2. What is the spatial configuration of existing green spaces and mixed-uses in the gated communities of “Pablo VI”, “La Felicidad” and “Ciudadela Colsubsidio in Bogota”? 3. How the degree of walkability is affected by the existing land uses and green spaces in the gated communities of “Pablo VI”, “La Felicidad” and “Ciudadela Colsubsidio” in Bogota?
5. Summary of results. This section will briefly review the key findings of the analysis to derive design implications and reference values for future studies and developments, including my studio C project. It is important to note that all outcomes and procedures were included in the proposed matrix, which was presented as the conclusion of my studio B research.
Walkability. Overall the walkability measures report conflicting results. Whereas the PCA values and node density show highly walkable values, the majority of pedestrian roads are blocked to public access by fences or walls. Likewise, although some roads inform higher connectivity scores, they allow high volume of traffic and car parks (Figure 5) . Pablo VI
La Felicidad
Ciudadela Colsubsidio
Figure 5. GIS graphics. Nodes intensity Source: Author.
Land uses Regarding land-uses, the analysis suggests that mix-uses value is lower with a remarkable dominance of residential uses. The variety of type buildings and architectural styles is limited, except for “Ciudadela Colsubsidio” which has several types of multi-story buildings and semidetached houses with certain degree of architectural richness. Pablo VI
Figure 6. GIS graphics. Lan uses. Source: Author.
La Felicidad
Ciudadela Colsubsidio
Green spaces. The analysis reports a highest proportion of green areas with more than 40% of buffer area in all cases. However, there are many unplanned left-over spaces without functional value known as Spaces left Over After Planning or SLOAP. In addition, some areas are private and once more they are surrounded by fences and control systems such as guards or security doors. Pablo VI
La Felicidad
Ciudadela Colsubsidio
Figure 7. GIS graphics. Green areas. Source: Author.
6. Conclusion Hence, this work has described the research plan for assessing walkability, green spaces, and mixeduses in three particular neighbourhoods of Bogota, Colombia such as “Pablo VI”, “La Felicidad” and “Ciudadela Colsubsidio". This work provided an exploratory methodology to examine the link between measured certain indicators and their correlation with the subjective point of view of the author. The analysis showed that although both objective measures and observations might deliver conflicting results and not always conclusive, they are key factors for enhancing the quality of life delivered by gated environments. Certainly, it requires further research and considers other variables and instruments such as 3d analysis, and questionnaire surveys to inform decisions in urban design and planning.
References Annerstedt van den Bosch, M., Mudu, P., Uscila, V., Barrdahl, M., Kulinkina, A., Staatsen, B., Swart, W., Kruize, H., Zurlyte, I., Egorov, A.I., 2016. Development of an urban green space indicator and the public health rationale. Scand J Public Health 44, 159–167. https://doi.org/10.1177/1403494815615444 Bentley, I., Alcock, A., Murrain. P., McGlynn. and Graham, S. (1985). Responsive Environments. 1 ed. Great Britain: Elsevier. Cervero R. (1996). Mixed land-uses and commuting: Evidence from the American Housing Survey. Transportation Research Part A, 30(5), 361-377. Gehrke, S. (2000) Land Use Mix and Pedestrian Travel Behavior: Advancements in Conceptualization and Measurement. doi: 10.15760/etd.5361. Gori, S., Nigro, M. and Petrelli, M. (2014) ‘Walkability Indicators for Pedestrian-Friendly Design’, Transportation Research Record: Journal of the Transportation Research Board, 2464(1), pp. 38–45. doi: 10.3141/2464-05. Jansson, Märit. (2014). Green space in compact cities: the benefits and values of urban ecosystem services in planning. Nordic Journal of Architectural Research. 2014. 139-160. http://arkitekturforskning.net/na/article/view/498 Lo, R. H. (2009) ‘Walkability: what is it?’, Journal of Urbanism: International Research on Placemaking and Urban Sustainability, 2(2), pp. 145–166. doi: 10.1080/17549170903092867. Manaugh, K., Kreider, T., 2013. What is mixed use? Presenting an interaction method for measuring land use mix. JTLU 6, 63. https://doi.org/10.5198/jtlu.v6i1.291 Mavoa, S. et al. (2018) ‘Identifying appropriate land-use mix measures for use in a national walkability index’, Journal of Transport and Land Use, 11(1). doi: 10.5198/jtlu.2018.1132. Rafiemanzelata, R., Emadi, M. I. and Kamali, A. J. (2016) ‘City sustainability: the influence of walkability on built environments.’ 3rd Conference on Sustainable Urban Mobility. [Online] 26th May [Accessed 22th August 2019] https://doi.org/10.1016/j.trpro.2017.05.074 Russo, A., Cirella, G., 2018. Modern Compact Cities: How Much Greenery Do We Need? IJERPH 15, 2180. https://doi.org/10.3390/ijerph15102180 Ryan, S. B. (2003) ‘Economic Benefits of A Walkable Community’, p. 2. Taylor, L. and Hochuli, D. F. (2017) ‘Defining greenspace: Multiple uses across multiple disciplines’, Landscape and Urban Planning, 158, pp. 25–38. doi: 10.1016/j.landurbplan.2016.09.024.
UCL, 2016. depthmapX: visual and spatial network analysis software [WWW Document]. The Bartlett School of Architecture. URL https://www.ucl.ac.uk/bartlett/architecture/research/spacesyntax/depthmapx (accessed 7.6.20).