Sustainable Urbanism: Plurality of Spaces

*M. Tawfique Rahman and Fauzia Rahman Mouri* 

#### **Abstract**

 "Sustainability" revolves around 3Rs—Reduce, Reuse and Recycle. In urbanism, these three trails correlates and coexists in many forms but "Reuse" of space is hardly one term that we use or think of. The mega cities of recently developing Asian continent are bustling with people which grow every day. Such a city is the capital of Bangladesh—Dhaka. The population of Dhaka city has reached 18 million in 2016 marking it as the fastest growing mega city regarding density which is 45,000 people/km2 . The city lacks minimum public open spaces and recreational urban areas. Under the circumstances, it is time to think differently to lay a broad and long-term programmatic responses to solve public spaces demand not only to reach environmental stability but also to ensure sustainability. This chapter tries to locate some sites in the city which are used for a period of time of the day and left unused for a certain period and offers proposals to reuse those sites as public recreational spaces. We call such proposal as "plurality of spaces". Large datasets were collected and ran through simulation showing the possible changes in the urban areas which may create a sustainable urban pattern.

**Keywords:** sustainability, urban, multiplicity, plurality of spaces, simulation, grasshopper

#### **1. Introduction**

While sustainable buildings are the units to attain sustainability, reaching sustainable urbanism or cities, is the ultimate demand of the new era. Dhaka city reached mile stone of density 45,000 people/km<sup>2</sup> [1] but in 2009, for the first time in history, world urban population has reached 51% [2]. Putting the rural population behind and the trend is only uprising. At present, the ratio is 56:44% with a prediction to reach 68:22% by 2050. Concerning though 90% of this growth will take place in Asia and Africa alone [3]. The fastest growing mega cities are in third world countries and on top of the list, according to density, consecutively holding the first position for last three years is the capital of Bangladesh-Dhaka. As it happens in any other densely populated city, the land value has launched to a sky-rocketing price and devaoured any land that is left unused or could be used. Unfortunately, the open spaces of the city has fallen under the embezzlement as well. As the aim of future is to attain sustainability, the research looked closely into the term of sustainability and of a thousand many varieties took the part signifying "reuse". This chapter suggested whether if there can be places to reuse in a densely packed city like Dhaka and add extra to present condition of the public spaces or not.

#### **1.1 The ideal density and the condition of Dhaka and multiplicity of spaces**

Even though it is high time to understand urban settlements and cities from different perspective, there are certainly no proper method or mathematical equation or deductive methods that with certainly can say what should be the ideal density of a city. But in 2012, as suggested by Wendell Cox, Hong Kong was the "smart growth ideal" for having the highest urban population density in the developed world [1]. However, if the third world countries like Bangladesh are taken into account, the calculations fall apart. Dhaka, currently has a population of 18 million, making its density 45,000 person/km2 [1]. Compared with Dhaka, Hong Kong has a density of 7075 person/km2 [7]. Dhaka already has six times more density than Hong Kong. Every day approximately 3000 people come to Dhaka [4]. Merges in for the promise of better income of a megacity making the annual growth rate 4.2% [5], which is more than five times of Hong Kong's growth rate, that is 8% [4]. It is fairly obvious that the situation of Dhaka city is anything but furthest to any ideal condition. An ideal sustainable city should have 25% open space accessible and enjoyable for every one, of which 25% should be green [4]. Contrary to the ideal situation Dhaka city has 12% of open space areas. Of which only 3–4% is green [6]. The city tremendously lacks public spaces. The term sustainability revolves around three Rs, which are reduce, reuse, and recycle. In a city, it is understandable to reduce the consumption of materials or energy or recycle the waste or power, but how to engage the city inhabitants to reuse the basic urban amenities like—Space is space a reusable entity at all? How to perceive space, is there anyway to change the notion and perspective of the way a space is used and reuse it?

The existing places with their existing infrastructure and functions which ceases to function for period of time and can be used for a different function for that particular period has the qualities of multiple use. This chapter identifies such spaces with these attributes as-multiplicity of that space. These are the spaces, which are of main consideration in the research, to see if these exist or not? If exist, is it possible to use them for the time when these are not functioning as per original use, and if these can be turned into public usable spaces.

#### **1.2 Objective of the study**

The objective of the study was to find out places those could be used as public spaces for a certain period of the day and thus enhancing the living experiences of the city. Also in doing so, certain spaces can be marked which later can become models for the future expansion. Thus, the research hopes that the future smart cities, from gathering big data and processing it, can self generate the expansion keeping these sorts of spaces in between the urban areas, which will enhance the living condition as well as by reusing spaces, will increase efficiency. Sustainability is not only about reducing or recycling, the inhabitants and the policy-makers also need to understand that it is about reusing spaces as well.

#### **1.3 Scope of the study**

 As much as the inhabitants want more public open spaces in the city, the highly dense Dhaka city is incapable of creating new urban open spaces because of the sky rocketing price of land and the existing open spaces are also facing trouble to remain so. We selected a small portion of Dhaka city, which is the "Shaat Rasta" road. The site chosen starts from Mohakhali, Nabisco junction in the north and ends at the "Shaat Rasta" junction in the south. We started to look for places that will give us the following advantages


By fulfilling the above conditions, these spaces/places can be used for multiple functions and that can be called the "Multiplicity of spaces".

#### **2. Methodology**

 The research was conducted based on computer simulation, case studies as literature review, and on intensive field data collection. Based on the findings, some criteria for spaces, which can be used for multiple functions, have been established. After selecting the criteria or parameters for multiply usable space, five sites were marked suitable for the operation and simulation. Then a questioner-based research was conducted among the people around the locality to find out their needs and tried to fulfill those needs in small-scale contributions in the proposed sites. Case studies were done to understand how other places are used as multiple functions holding spaces during different time of the day and such attributes and observations were later implemented as strategies in the proposed areas. One of the such case studies were on "Manek Chawk," Ahmedabad, India.

 As mentioned earlier, a certain portion of Dhaka city named the Shaat Rasta was chosen for the experiment. It is a 2.5 km stretch starting from Mohakhali flyover till the Sonargaon node and it is one of the most important roads of Dhaka city. The road runs parallel with one of the main arterial roads of Dhaka city through an industrial zone and it has residential blocks on both sides of it. Both the sides are sprawling with legal and illegal commercial settlements. The whole area with a radius taken of 3 km from the mid point of the stretch, has a population of ninety thousand (90,000) people with 9.3% open space including the roads and pedestrian strips dedicated for the inhabitants of the area [7]. However, there is a public park situated at the corner of one of the residences but then again, it is so insignificant that taking it in to account does not change much in the total sum of open spaces. Even though the public park remains far away from most of the residential area and does not work properly because of its location and mode of transportation unavailability.

The site was divided into blocks and through rigorous data collection all the infrastructure and their uses were sorted out along with the urban amenities, infrastructure, drainage system, users and function, how many stories are there, etc. The primary criterion was that, the spaces should have some functions already instilled to them. But physically without damaging or altering the present infrastructure and function, if there are any opportunities laying to reuse the spaces for some other functions in any of the time.

 It is found through data collection that the whole stretch has 14 refueling stations where compressed natural gas (CNG) is sold as fuel. As a decree from the government, the CNG stations are not to run from 5 to 9 pm every day. Among the 14, there are 5 refueling stations which along with CNG sold gasoline, hence these five were fully/partly operational every day of the week and year. Hence nine CNG station were selected which cease to operate every day from 5 to 9 pm and those sites during that period of time are left unused. These nine sites possibly can be used for multiple functions and this attribute of the spaces were called the multiplicity of space. **Figure 1** shows the 2.5 km long stretch that has been selected for the research.

**Figure 1.**  *Chosen area with types of use.* 

The color-coded buildings are shown according to their use and the legend is given. All the data are collected on the site by authors with help of different means.

#### **2.1 Space syntax**

 After selecting the sites, the whole area map was put in space syntax program. Space syntax research attempts to find effects of spaces in a built form by directly addressing the physical and spatial complexity in the built form. In space syntax, the built environment is a complex system of spaces, which can be analyzed configurationally and point out the under lying patterns and connectivity [6]. The technique is simple where an axial map of the selected urban area and its context is constructed and then the connectivity particular sites were analyzed. Based on axial map of the area, imaginary grids were prepared which individually acted as an urban island/urban block. Each block is surrounded by axial lines and street intersections were marked as grid intersection points or meeting nodes of axial lines. Thus, the blocks were selected as areas to check the connectivity with the local people and fabric of the urban area. For research, the area of interest was the whole stretch and connectivity of the nine selected CNG refueling hubs were tested in relation to the existing residential area. Out of nine selected sites, five showed well established connection with the neighborhood. That means those five CNG stations were easily accessible for the inhabitants and further experiments were pursued on these five sites. **Table 1** shows the connectivity of the selected sites with the residential area around. The more the number of connectivity, it shows more connection with the locality. Global and local integers were taken into account selecting a radius of 3 km (n = 3) and was calculated using the space syntax program in a range of 0–5. The more the number, the better connected the site is. At the end, if the site was selected or not is shown in the last column.

*Sustainable Urbanism: Plurality of Spaces DOI: http://dx.doi.org/10.5772/intechopen.87836* 


#### **Table 1.**

*Connectivity of the nine refueling sites in the local and global perspective.* 

 The given chart shows the connectivity, global integer, and local integer, where connectivity means in how many ways the particular site chosen is connected to the neighborhood, the global integer shows how well the site is connected with the rest of the city and local integer shows how well connected it is with the local neighborhoods. The higher the value from 1 to 5 scale, the better connected it is. Once the five sites were selected, the selection went through the next level of experiment which is computer simulation to see how these sites may work under certain parameters. **Figure 2** shows the selected and rejected sites, which are marked according to their numbers. The images show the space syntax find outs. With the red being most used and populated zone, marks the main artery road. The green to blue shades show according to lesser used and less connected roads. **Figure 2a** shows the overall connectivity of the roads with each other and with the blocks of the selected area. **Figure 2b** shows the primarily selected nine sites are situated in the mesh of connectivity both in terms of roads and local area. **Figure 2c** shows the final selection of the sites. Most connected roads also shows the nodes which are understood as joints. The more connected the joints are in a block, the better they perform. Because the clear joints in a city are mostly strategic moments of structures which should be highly perceptive [8]. The research wanted to find out the most perceptive joints to intervene. Hence, selecting five points out of nine at the end.

#### **2.2 Grasshopper simulation**

 After selecting the sites, computer simulation were run to understand the social behavior pattern of the locals. In such a case, a cell is created, which will populate itself in any given open space in the area selected. For an example, the road chosen is the Shaat Rasta, Mohakhali. This road was assigned with point X on the north and point Y on the south. Then programmed the cell to populate in any point which is in the proximity to the local connection but only if the place is vacant. The cell does not populate in any area since there are no vacant spaces. Then time parameter was added to show the algorithm that from 5 to 9 pm there are some vacant spaces. The cell then automatically started to generate at those selected points since they recognized the spaces as vacant. Later some other parameters were attributed to the cells, which attract people such as food, libraries, and ice cream parlors. The simulation then shows that the cell already starts to attract people and the places/sites start to become urban hubs for the time being. The figures show the conditions of the simulations. The pentagon shape denotes the cell that is programmed to generate if the places are vacant or usable during the period. At first, the selected sites are not populated by the pentagon cells, but later the cells are fully and spontaneously generated in the sites.

The prime function of the cell was to populate space, when it can get favorable condition. No function was assigned to any cell. The function of the cell is to be decided according to demand manually later. For intervening with the functions rather than a top-down system, the decisions were taken on a bottom-up system, where the peoples choice was given priority. In cases where the closest neighbors in their questionnaires felt the need of a restaurant or a library or snacks joints, according to their need, later on, it was provided. But as the most of the need base was food related, a simulation with food and human connection was ran. The simulation parameters were pre-selected in the notion that human beings (shown as dots in **Figure 3**) are attracted to food carts or food dispensing functions (shown as a red pentagon) and when those pentagon cells occupied a vacant multiply usable space, with time, more and more people start to come over and gather around. Below a site blow up of a simulation ran is shown **Figure 4**.

#### **2.3 Findings**

The following outcomes were intended to achieve, if the strategies are implemented:


The study and the possible solutions focuses only on some chosen small-scale spaces in an area of Dhaka city within its limited scope to find out whether multiplicity of spaces works to solve the issue, that is the current lacking of open urban space in the broad area of the metropolis. Also as a theory whether multiplicity of spaces is a solution for future sustainable development or not.

 Since it was not possible for the team to implement the ideas in reality, we have taken the liberty to run simulations and see what the possible outcomes could be in reality. Softwares used for the simulations are Grasshopper and Rhyno based on which works under certain parameters given and run through as such. That is to say, under certain parameters given in to the computer codes, the result shown are different accordingly. While running simulations on a city, the matrix and parameters are much more complex and vast, hence we can assume that the results may vary if more parameters are added. After the simulations results shown the possible sites with potentials, the spaces were required to design and may require to hold the potential function in the selected sites. The simulation shows that adding the five sites, increases the open area percentage from 9.3 to 12.8%. More research and possibility of adding such multiply usable spaces shows that the existing situations of the Dhaka city can be improved. Finding more of such places surely enhances the present quality of living and also adds to the open spaces of the city that a city needs. Such an experiment also shows that keeping the existing infrastructure and reusing them, inevitably attenuate towards a more sustainable city and mindset.

#### **Figure 2.**

*Connectivity of sites in space syntax. (a) Whole area connectivity in space syntax. (b) Sites with connectivity map. (c) Selected sites after consideration.* 

#### **Figure 3.**

*Simulations at different time periods. (a) Simulation 1/without time parameter. (b) Simulation 2/time 12 am–5 pm. (c) Simulation 3/time 5 pm–9 pm.* 

#### **Figure 4.**

*Simulation results. (a) Blow up area in simulation. (b) Cell and population. (c) Population increase from 5 to 9 pm.* 

#### **3. Conclusion**

 Dhaka, the capital of Bangladesh, is thriving under the pressure of population and densely unorganized proliferation of amenities. It has limited number of open spaces which are not enough for the inhabitants and more over the number of people is growing every day. The urban spaces have become a need which is yet not well understood or monitored. Even the existing condition of the open areas where people can gather for certain refreshment is not user friendly. Therefore the

 research tried to look forward to some alternative solutions by changing the value and the view point of how a space or a public space is seen. Henry Lefebvre in his writings repeatedly said the production of space is a spontaneous matter which is affected by the locality and the mindset [9]. In this chapter, it is tried to incorporate thoughts that will bring change in the system where a place is presented with its multiple use attribute and due to the lack of proper defined space, people of the surroundings will take the spaces into their consideration and start enjoying. All of these spaces are well integrated at local level. The study tried to look for spaces which can be used for different functions at different period of the day and marked as spaces that have the potentiality to be multiply used. This small intervention is a certain step towards multiplicity in a metropolitan like Dhaka. The reuse of such spaces can be introduced to people and by creating efficiency and access, it is possible to present the inhabitants with a little breathing space in the cityscape itself. Use of cellular automata and computer simulations were another side of the experiment where, depending on the parameters, the results can vary from little or no change to large scale differences. For such experiments, large quantity of data sample is required and analyzing such large data set may give different answersduring different iterations or conditions. It is therefore agreed that there are many limitations of the study, even then we are much hopeful that such certain steps may bring change to the living condition that is at present an unhealthy reality.

#### **Acknowledgements**

We thank the students of South East University, Architecture Department 20–21 batch for helping us gather and analyze the data on the urban area selected. We also thank the student team to help us run the Grasshopper simulation and programing.

#### **Author details**

M. Tawfique Rahman1 \* and Fauzia Rahman Mouri<sup>2</sup>

1 Department of Architecture, South East University, Dhaka, Bangladesh

2 Department of Architecture, American International University, Dhaka, Bangladesh

\*Address all correspondence to: mirat147@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Sustainable Urbanism: Plurality of Spaces DOI: http://dx.doi.org/10.5772/intechopen.87836* 

#### **References**

[1] Cox W. Evolving Urban Form: Dhaka [Internet]. 2012. Available from: http://www.newgeography.com/ content/003004-evolving-urban-formdhaka [Accessed: December 19, 2018]

[2] UN Economic and Social Affairs [Internet]. 2015. Available from: http:// www.undp.org [Accessed: December 21, 2018]

[3] Worldometers.worldometers. com [Internet]. 2019. Available from: http://www.worldometers.info/worldpopulation/china-hong-kong-sarpopulation [Accessed: January 30, 2019]

[4] Nilufer F. Urban life and usable public space in Dhaka [thesis report]. Dhaka: Buet; 2000

[5] Judy BL. Dhaka: Improving living condition. Worldbank studies. Dhaka: World Bank; 2007

[6] Hillier B. The Common Language of Space: A Way of Looking at Social Economic and Environmental Functioning of Cities on a Common Basis. Space Syntax Laboratory, Common Language of Space. 2008. pp. 23-46

[7] Statistics. Bangladesh Bureau of Statistics Report. Dhaka: Bangladesh Bureau of Statistics. 2019. Available from: http://www.bbs.gov.bd/

[8] Lynch K. The Image of the City. Massachusetts: MIT Press; 1960

[9] Lefebvre H. The Production of Space. Oxford, OX, UK: Blackwell; 1991

**499**

**Chapter 41**

**Abstract**

comparatively.

steel construction

**1. Introduction**

The Investigation of the

The Sample of Ankara City

*Gökhan Durmuş and Akın Ünal*

Sustainability of the Existing Steel

Pedestrian Overpasses According to

the New Steel Structure Regulation:

The current state of the steel pedestrian overpasses, which were selected from different regions of Ankara, was designed in terms of engineering. Three pedestrian overpasses, which are important in terms of loss of life and property of the city, have been identified. In this study, it will be determined whether pedestrian overpasses dimensioned according to linear analysis primarily meet the design criteria according to the old steel structure regulation. In addition, the conformity of the design rules in the regulation on principles of design, calculation, and construction of steel structures entered into force in 2016 will be investigated. The conformity of crosswalk that is the ductility level of the steel frame and high ductility steel frame entered into force in 2016 will be investigated. As a result, internal forces of selected column and beam elements are given in graphs and tables at the result of the study

**Keywords:** steel structure design, linear analysis, nonlinear analysis, overpass,

Turkey is located on an active earthquake zone and has recently entered a rapid construction process. Especially in the recent years, there has been an increase in the application area of steel structures. However, the design rules of steel structures are particularly important. In this direction in Turkey, on September 1, 2016, Design, Calculation and Construction Principles of Steel Structures (ÇYTHY), and on January 1, 2019, Turkey Earthquake Building Regulation (TBDY) entered into force. The ratio of steel structures to all structures is about 50% in Europe and America. This ratio is a very small value, such as 0.3% in Turkey. Although the exact values are not known, it is thought that steel structures are used in industrial buildings by 6% and in residential buildings by 1–2%. In Turkey, most of the steel structures are industrial-type structures [1, 2]. The remaining part consists of towers, energy infrastructures, bridges, pedestrian overpasses, and commercial structures. Application of multistory steel structures is very little. The reason of

#### **Chapter 41**
