24th ISUF International Conference 27th-29th September 2017 VALENCIA City and territory in the Globalization Age Conference proceedings

The impact of bridges on spatial transformation of urban pattern: The case of ,

Demet Yesiltepe, Ayse Sema Kubat Istanbul Technical University, Faculty of Architecture, Department of City and Regional Planning. E-mail: [email protected], [email protected]

Abstract. Transportation projects especially subways, bridges and new transportation modes gained importance in İstanbul in the last decades. The Golden Horn Metro Bridge, which connects two parts of the European side of İstanbul and has a station on the bridge, has caused criticisms not just because of having these unique characteristics but also because of the effects of the bridge on the silhouette of Historical Peninsula. The main aim of this paper is to analyze the impact of bridges on urban pattern and to explore the different influences of metro and vehicular bridges. Within this scope, three bridges located over the Golden Horn, which created connections between historical site of İstanbul and the newly developed CBD, are chosen as case study. Areas within 1km zones around the bridges are analysed separately, and the urban pattern (street pattern, block size, building data) is investigated comparatively through GIS. The layers of the past geographies (Historical GIS) and the Space Syntax (angular segment based integration and choice) analyses are conducted for demonstrating spatial changes. The findings indicate that the study area has transformed into more divided streets and urban blocks and the number of buildings increased through time. Moreover, it is observed that the metro-rail bridge system has less impact on urban pattern. This study contributes to urban planning/design not only by analysing comparatively the transformation of the urban pattern during the pre- and post-construction processes of the bridges but also by evaluating the impact of the bridges through a quantitative and innovative method.

Keywords: Urban pattern, transportation projects, the Golden Horn Metro Bridge, Istanbul

Introduction The main purpose of this study is to analyse the influence of bridges on urban pattern and The Golden Horn region of Istanbul constitutes to explore the different effects of metro and a significant historical part of the city and this vehicular bridges. The goals of this paper are: area has changed dramatically during its history. I. To explore the pattern of settlements The bridges which have been constructed of the Golden Horn and determine its level of along the Golden Horn are essential examples transformation of these changes (Figure 1). Due to the effect of II. To analyse the spatial structure of the these bridges, the form of the neighbourhoods area by using Historical GIS method on the Golden Horn has changed, and by III. To discover the different effects of examining this change, this paper analyses vehicular-pedestrian bridges and metro- the major influences of bridges on the urban pedestrian bridge pattern of cities. IV. To make a mathematical comparison also by using Space Syntax methodology.

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Urban morphology is an approach which bridges were selected to facilitate an analysis is used to conceive the physical form. This of the influence of bridges on settlements. concept explores how towns have grown and Areas within 1km zones around the bridges developed through small scale analyses of are analysed separately, and the urban pattern buildings, plots and streets, and also macro (street pattern, block size, building data) is scale studies (Larkham 2005). Buildings, investigated comparatively through GIS. The gardens, parks, streets are the main elements layers of the past geographies (Historical GIS) of any morphological analysis; thus, they have and the Space Syntax (angular segment based dynamic relationships: each one shapes the integration and choice) analyses are conducted others and is also influenced by them (Moudon for demonstrating spatial changes. 1997). Empirical evidence is used to determine It is believed that cities can be read according 1km as a distance that people can walk (Lee to their physical form. In addition to this, there and Moudon 2006). To determine the specific is an acknowledgement that morphological study area, 1km zones around the bridges were analysis is based on three principles: created and the mathematical data inside these 1. Urban form can be defined by three elements: buffers is analysed separately for three bridges the buildings and their open spaces, the plots/ (Figure 2). lots and the streets, The neighbourhoods around the bridges 2. Urban form can be understood from the were selected as a study area due to the building or lot, the street, the city, and the historical processes they have undergone, and region, also due to the bridges themselves as they were 3. Urban form can be understood historically built during different time periods. There are through the transformation and replacement it many important examples of Ottoman urban has undergone (Moudon 1997). layouts in the study area. While one side of As a part of this study, street patterns, the area is historic, the other side is connected buildings and urban blocks have been analyzed to more developed areas. As a part of this not only to explore the urban form, but also to study, not only the pre-, post- construction discover the transformations it has undergone. process of bridges but also two-time periods, Moreover, space syntax methodology is also which urban pattern changed dramatically, adapted to this paper. This methodology is were also examined. During the first – 1922 developed by a team led by Bill Hillier (1996). – the Islamic city image changed to that of a Space Syntax is essential for urban planning more cosmopolitan city; the organic pattern and design studies as it gives consistent started to shift toward a grid pattern and the results based on the mathematical data created Republic was about to be proclaimed. During according to the open spaces within cities. the second – 1996 – several planning decisions This methodology provides evidence-based were implemented in the study area, thus the learning by creating a framework that allows patterns of the settlements around the bridges comparisons between settlements to be were changed. made(Peponis 1990). On the other hand, to discover the transformations of street patterns, buildings and urban blocks, Historical GIS methodology is adapted to the study. A Geographic Methodology Information System (GIS) links locations and their attributes so that they can be analyzed, Within the scope of this paper, three bridges whether by their geographical characteristics located over the Golden Horn, which created or factors such as distance, location, or links between historical site of İstanbul and the physical characteristics. The main organization newly developed CBD, are chosen as study area. principle of GIS is based on location, which Three bridges which span the Golden Horn; is encoded as geographical coordinates. With the Atatürk, Galata and Golden Horn Metro the location data established, it then becomes

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Figure 1. The bridges located over the Golden Horn (a. Ataturk Bridge, b. , c. the Golden Horn Metro Bridge)

Figure 2. Location of the bridges and the case area a powerful tool for the analysis and integration added to GIS, the information it contains can be of other variables (Knowles, 2002). extracted, analyzed and compared with other There are several advantages of Historical data (Knowles & Hillier, 2008). Therefore, GIS; first, the spatial data reveals where the data the data about street pattern, urban blocks and is located and thus, it can be used for integrating buildings isgenerated for different time periods any data which seems incompatible. Secondly, by using this methodology (Figure 3). Historical GIS allows data to be visualized by Moreover, angular segment based integration using maps and other techniques such as virtual and choice values are also calculated through landscapes and animation. Thirdly, GIS allows the use of Depthmap10 software. Choice can different forms of spatial analysis to be made be defined as the possibility for each segment where the coordinate locations of the features to be selected by pedestrians as the shortest under examination are a specific part of the route. A choice analysis means the “through analysis (Gregory & Healey, 2007; Gregory et movement” potential of each segment in a al., 2001). Moreover, once a historical map is system (Al Sayed et al., 2014).Integration is

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Figure 3. Historical layers of the Golden Horn defined as the distance of each segment to all On the other hand, the construction process other segments in a system (Hillier et al., 2012). of the last bridge, the Golden Horn Metro Therefore, it can be said that while a choice Bridge, first started with an announcement analysis examines the through movement by the mayor of metropolitan Istanbul, Kadir potential, an integration analysis examines its Topbaş, in 2004 and the project was approved “to movement” potential of a given system. in 2009 by the Conservation Board. Although Integration shows the degree to which a line is the Historical Peninsula, where an abutment more integrated, or segregated, from a system of the bridge is located, has been on the World as a whole (Jacoby, 2006). Heritage Site list since 1985, the bridge project was not reported to UNESCO (Vardar 2014). When the construction of the project began Analysis in 2009, UNESCO stated that this project Historical Process would damage the silhouette of the Historical Peninsula and warned that the area could be Historical background of the bridges over the added to the World Heritage in Danger category Golden Horn dates to 1930s. In 1836, the first (Bilgehan 2015). After this warning, the project historically-verifiable bridge, Unkapanı (new was revised and the height was decreased from Atatürk Bridge) bridge was built across the 82 meters to 65 meters and construction work Golden Horn. After this period, because of the was halted until 2011 (Vardar 2014). In 2012, growing population and new palace for the the revised design of the project was approved Sultan, a second bridge was needed. Therefore, and the bridge eventually entered service in the “Cisr-iCedid” bridge, now known as the Galata Bridge, was built in 1845 (Cekmis February 2014. Gorgulu and Hacihasanoglu 2012).

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Spatial and Syntactic Changes the construction of the second bridge (Table 4). Therefore, it is possible to state that after Spatial changes before and after the construction the construction of the second bridge, the area of the Unkapanı (Atatürk) Bridge become more accessible and connected. At the beginning of 1830’s, the Historical Peninsula was the centre of the settlement and the Galata region was limited by its old Spatial changes during the 20th Century borders. The street pattern was usually organic, except at the north side of the Golden Horn. During the 20th century, there were many Additionally, Topkapı Palace, the Suleymaniye different processes underway in the study and Yeni Valide mosques, the Grand Bazaar area. Therefore, it is constructive to conduct and the other commercial buildings and large an analysis across two different time periods. mosques were the most prominent structures First, in 1922, the Republic was about to be of the period. During this period, the number proclaimed and a tram lane was added to the of street segments totalled 272 and average Galata Bridge. The most important buildings number of buildings totalled 148. Moreover, were the Sirkeci railway terminal (on the the average area of urban blocks was 29853 Historical Peninsula), two hospitals (Beyoğlu square meters (Table 1). and Sankt Georgs) and the town hall (located in After the construction of the first bridge, the Galata) in this time period. Additionally, after data shows that the number of street segments the establishment of the Republic of Turkey, increased to 303 and the average area of urban Topkapı Palace was transformed into a museum blocks decreased to 25301 square meters. at the date April 1924 and it was also the first Furthermore, the average length of streets museum of the Republic of Turkey. Ministry of declined from 151 meters to 140 meters and war was transformed into a university building the average area of buildings decreased from in 1923. 412 square meters to 385 square meters. To In 1933, after the proclamation of the conclude, the area around the first bridge Republic, three different urban planners were transformed into more divided streets and invited to the city and a new planning approach urban blocks after the construction of the was developed. One of the most important Unkapanı Bridge. events of the period was the invitation On the other hand, after the construction of extended to Prost. His plans affected Istanbul the first bridge, the street network configuration in a number of different ways – in particular, of the study area underwent some changes too a scheme to create different functional zones (Table 2). As shown in the table, the choice for different activities. One consequence (n) value increased from 3.73 to 4.15 and of this was the relocation of all industrial the choice within 400 meters increased from facilities to the Golden Horn, which affected 2.14 to 2.39. In addition, integration (n) value the area in a negative way as the shore became increased from 2.05 to 2.28 in this time period. heavily polluted and the area soon fell into Spatial changes before and after the ruin. However, Prost was also responsible construction of the Cisr-iCedid (Galata)Bridge for limiting the height of buildings, which After the construction of the second bridge successfully preserved the silhouette of the in 1845, the number of street segments rose Golden Horn (Kuban, 1996). from 277 to 287 and the number of buildings Under the government of Prime Minister increased from 314 to 365 around the bridge. Adnan Menderes between 1950 and 1960, the Moreover, average area of buildings decreased whole city underwent some changes. These from 545 square meters to 482 square meters included the introduction of wide boulevards, (Table 3). which Menderes took from the examples On the other hand, it is observed that ln of European countries. The road between (n) increased from 2.28 to 2.34 and ln (r3) Unkapanı and Yenikapı (which is located on the increased from 1.79 to 1.94. And finally, south side of the Atatürk Bridge) was widened. connectivity increased from 0.48 to 0.52 after From Galata to Dolmabahçe, from Karaköy to

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Azapkapı and between the two bridges over the connections between the heart of the city (the Golden Horn, more new boulevards were built commercial center) and the Byzantine gates (Kuban, 1996). (Kubat, 1999). During the 1980s, the city underwent many Spatial changes before and after the economic, social and political transformations. construction of the Golden Horn Metro Bridge A new master plan was created, and there was In 2016, after the construction of the last bridge, also a plan to remove the industrial areas from the number of street segments increased from the shores of the Golden Horn. The planned 17168 to 17507 and the average length of street demolitions, which are now remembered as segments increased from 6, 48 to 6, 53. The “Dalan Operations” (after Bedrettin Dalan, number of buildings increased from 269 to 298 the mayor at the time), were given the go- and the average area of buildings raise from ahead, and more than 4000 buildings up to 431 square meters to 558 square meters (Table 50-100 meters inland of the Golden Horn 5). The study area now contained Istanbul shoreline were expropriated. 696 factories and Ticaret University and Kadir Has University; 2020 offices were demolished and relocated. thus, these buildings can be thought as the Furthermore, the shoreline of the most significant reason for the changes in the Golden Horn (representing about a million number of buildings and the average area of square kilometres) was transformed into parks the buildings. and gardens (Erbey, 2009). After the construction of the last bridge, By the beginning of the 21st century, the Golden Horn Metro Bridge, a very slight communication within the core of Istanbul was change in syntactic values around the bridge improved. The main aim of this period was was observed. It is determined that the values to provide an uninterrupted communication of choice (n) decreased and choice within 400 network across the Historical Peninsula by meters and integration (r3) increased slightly creating new arteries so that these could make while choice within 800 meters and ln(n) remained stable (Table 6).

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Conclusion with both Kubat’s analyses and the overall values reported in 2016 (Table 7). Thus, when Intelligibility is a value which is derived from considering whole case area, the spatial pattern the correlation between connectivity and around the bridges is more intelligible. global integration. A high correlation between As result of these analyses, it is possible to two factors means that the spatial structure state that the study area has transformed into is intelligible, and low correlation means more divided streets and urban blocks, and that the spatial structure is not intelligible. the number of buildings increased over these Kubat(1997), discovered that the intelligibility periods. Although it is not possible to claim value of the Anatolian towns she analyzed that the bridges are the only factors behind was 0.350, while that of the Islington area of these changes, it can be stated that the bridges London has been reported at 0.61-0.26 (Hillier have created more integrated and accessible 1989), and that of Athens has been reported at spaces. Therefore, as planned, Galata and 0.790 (Peponis et al. 1989). Karaköy regions have become more accessible The intelligibility values of the areas and more preferred areas; thus, new functions around the three bridges are higher compared and buildings have been constructed.

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This study is an attempt to contribute to the Configurational Theory of Architecture.’ literature by explaining the influences of bridges edited by Space Syntax. London, United on urban morphological characteristics and Kingdom: Cambridge University Press. street network configurations. Furthermore, the Retrieved February 3, 2015 (http://discovery. metro bridge-rail system of the Golden Horn ucl.ac.uk/3881/1/SITM.pdf). Metro Bridge has had less impact on the pattern Hillier, W. R. G., Yang, T., and Turner, A. of the settlements when it is compared with the (2012) ‘Normalising least angle choice impact of the vehicular bridges. The primary in Depthmap-and how it opens up new reason for these lower values is that there is perspectives on the global and local analysis no distinct, continuous pedestrian route in the of city space.’ Journal of Space syntax, 3(2), north-west direction. However, just as with 155-193. the Galata and Atatürk bridges, it is expected Jacoby, K. (2006) ‘What is space syntax: Does that with some new planning decisions (new the urban form of the city affect the level routes connected to the main sidewalks and of burglary and crime.’ Royal Institute of new functions around the Golden Horn Metro Architecture Stockholm. Bridge), the settlements around the bridge will Knowles, A. K. (2002) ‘Past Time, Past Place: become more accessible and integrated spaces. GIS for History.’ Knowles, A. K., and Hillier, A. (2008) ‘Placing history: how maps, spatial data, and GIS are References changing historical scholarship.’ ESRI, Inc.. Kuban, D. (1996) ‘İstanbul Bir Kent Tarihi.’ Al_Sayed, K., Turner, A., Hillier, B., Iida, Türkiye Ekonomik ve Toplumsal Tarih S., and Penn, A. (2014) ‘Space syntax Vakfı, İstanbul. methodology. A teaching textbook for the Kubat, A. S. (1997). The Morphological MSc Spatial Design: Architecture & Cities.’ Characteristics of Anatolian Fortified Towns. Bartlett School of Architecture, UCL: Environment and Planning B: Planning and London. Design 24(1):95–123. Bilgehan, Z. (2015) ‘UNESCO Artık Kubat, A. S. (1999) ‘The morphological Daha Anlayışlı.’ Retrieved (http://www. history of Istanbul.’ Urban Morphology, hurriyet.com.tr/unesco-artik-daha- 3(1), 28–41. anlayisli-28179189). Larkham, P. J. (2005) ‘Understanding Urban Cekmis Gorgulu, A., and Hacihasanoglu, I. Form?’ Urban Design 93:22–24. (2012) ‘Water Crossing Utopias of Istanbul : Lee, C., and Moudon, A. V. (2006) ‘Correlates Past and Future.’ Istanbul Technical of Walking for Transportation or University, Faculty of Architecture 9(2):67– Recreation Purposes.’ Journal of Physical 88. Activity & Health 3:77–98. Retrieved Erbey, D. E. (2009) ‘Haliç ’ te Dönü ş üm ve (http://216.92.169.205/alr/alr/files/jpah_6_ Tarihsel Süreklilik.’ Osmanlı Bankası Arşiv lee.pdf). ve Araştırma Merkezi Moudon, A. V. (1997) ‘Urban Morphology as Gregory, I. N., Kemp, K. K., and Mostern, an Emerging Interdisciplinary Field.’ Urban R. (2001) ‘Geographical Information and Morphology 1:3–10. historical research: Current progress and Peponis, J. (1990) ‘Space Syntax.’ Environment future directions.’ History and Computing, and Behavior 4(12):17–29. 13(1), 7– 23. Peponis, J., Hadjinikolaou, E., Livieratos,C., Gregory, I. N., and Healey, R. G. (2007) and Fatouros, D.(1989) ‘The Spatial Core ‘Historical GIS: Structuring, mapping and of Urban Culture.’ Ekistics 56(334/335):43– analysing geographies of the past.’ Progress 55. in Human Geography, 31(5), 638–653. Vardar, N. (2014) ‘Tüm Itirazların Ardından Hillier, B. (1989) ‘The Architecture of the Haliç Köprüsü.’ Retrieved (http://bianet. Urban Object.’ Ekistics 56(334/35):5–21. org/bianet/toplum/153027-tum-itirazlarin- Hillier, B. (1996) ‘Space Is the Machine: A ardindan-halic-koprusu).

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