Developing Rotterdam's skyline

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(1)CTBUH Journal International Journal on Tall Buildings and Urban Habitat. Tall buildings: design, construction and operation | 2012 Issue II. Capital Gate, Abu Dhabi Securing Iconic Structures Environmental Performance of the TTDI Developing Rotterdam’s Skyline Talking Tall: The Skyscraper Index Debating Tall: Is UNESCO Going Too Far? Tall Buildings in Numbers: Occupiable Telecommunication & Observation Towers.

(2) Inside News and Events 02 This Issue Steve Watts, CTBUH Trustee 04 CTBUH Latest Antony Wood, CTBUH Executive Director 05 Debating Tall: Is UNESCO Going Too Far? 06 Global News Highlights from the CTBUH global news archive. Case Study. CTBUH. 12. Case Study: Capital Gate, Abu Dhabi. 46 Helsinki: Developing a Finnish Vernacular for the High-rise? Antony Wood. Jeff Schofield Author Jeff Schofield, Associate RMJM Floor 27, Monarch Office Tower PO Box 6126 Dubai UAE t: +971 4 702 7626 f: +971 4 329 6444 e: j.schofield@rmjm.com www.rmjm.com. Jeff Schofield Since moving to RMJM Dubai in 2005, Jeff Schofield has lent his design expertise to a variety of large scale building developments, including mixed use, hospitality and high-rise projects.. 48 CTBUH Young Professionals Committee Launches Ambitious Agenda Kevin Brass. As an Associate at RMJM, Jeff leads the effort in providing sustainable solutions to all design projects in the office. He has developed a holistic approach to design that integrates sustainability, structure and architectural expression with the built form, in order to provide meaningful solutions for high-quality building designs. Jeff seeks to design in a contemporary yet contextual manner, to create modern sustainable buildings using the latest technology. g his Jeff currentlyy lives and works in Dubai. He began career in New York City and pursued his professional practice for more than 15 years in Paris, France. Jeff has projec pro jectt management managem mana gement ent an and d desi d esign gn exp experi erienc ence e on on a project design experience range of high profile projects. Jeff has specific experienc i e in i sustainable sustain i abl ble design design i and d project proje j ctt experience manage man agemen mentt of of larg llarge-scale arge-s e scal cale e publ p ublic ic pro projec jects ts thr throug oughou houtt management public projects throughout Europe, U.S.A and the Middle East.. 49 CTBUH Research Development Initiative: An Update Payam Bahrami 51 CTBUH on the Road CTBUH events around the world.. 18. 24. 32. Securing Iconic Structures Sean Ahrens & Stephen Yas The Environmental Performance of the TTDI Suraksha Bhatla & Joanna Gonçalves. Sean Ahrens. Stephen Yas. Aon Fire Protection Engineering Security Division 1000 Milwaukee Avenue, 5th floor Glenview, IL 60025 United States. 51 Diary Upcoming tall building events. t: +1 847 461 9359 f: +1 847 953 7793 sean.ahrens@aon.com www.aonsecurity.com. Stephen Yas, Design Principal MulvannyG2 (Shanghai) Architecture Ciro’s Plaza Suite 1905 388 Nanjing Xi Road Shanghai 200003 China. Developing Rotterdam’s Skyline Frank van der Hoeven & Steffen Nijhuis. Sean A. Ahrens Sean leads the security consulting practice at Aon FPE with over 19 years of experience, a majority of which has been in a security consulting function. He has been responsible for providing security threat and risk analysis, contingency planning, loss prevention, and force protection design and planning. Sean has provided design and construction administration for government, public, and private entities that encompass telecommunications, security, surveillance, and access control systems. He is well versed in the various trade and local authority issues impacting projects, and has specialized professional competence in security, access control systems, and force protection systems.. 52 Reviews Review of new books in the CTBUH Library. Stephen Yas Stephen has over 35 years experience working internationally. He specializes in architecture, urban design and interior design for large mixed-use projects. As design principal in the Shanghai office of MulvannyG2 Architecture, he is the design leader in china for the firm. Prior to MulvannyG2, Stephen leads his own firm in Chicago for 22 years. Prior to that he was a senior designer at SOM Chicago and Lohan Associates, as well as working in England and the Middle East.. 52 CTBUH in the Media Selection of media coverage 53 Comment Feedback on the past journal issue 53 What’s on the CTBUH Web? Featuring new content now available on the website. 38 Tall Buildings in Numbers A Look at Occupiable Telecommunication & Observation Towers 40 Design Research University of Nottingham 42 Talking Tall: The Skyscraper Index Andrew Lawrence. In 2005, the Abu Dhabi National Exhibitions Company (ADNEC) was created to drive forward the development of Abu Dhabi’s events sector. Plans were created with RMJM to build a state-of-the-art exhibition centre which would be the largest in the Gulf region and provide world class facilities for live events to flourish in Abu Dhabi.. • The vertical and horizontal cross-sections of the tower are all unique First of its Kind There are several innovations within the project’s design, including the dramatic 18-degree westward lean, which has earned it the title of “world’s furthest leaning manmade tower” from the Guinness book of world records (see Figure 1). It is also the first building in the world to use a pre-cambered core with a built-in lean of 350 millimeters that has been engineered to straighten with the addition of the upper floors. And it is the first building in the world to use vertical post-tensioning of the core to counter movement and support stresses created by the building’s overhang.. It was strongly felt that the entire development required a signature tower, a cutting-edge structure with a futuristic design,. aesthetic splendor and technical excellence to celebrate human achievement and reflect the dynamism of Abu Dhabi. Capital Gate is the result. The tower’s curvaceous shape draws strongly on the sea and desert – two elements that have great resonance in Abu Dhabi. The building’s form is meant to represent a swirling spiral of sand, while the curved canopy, known as the “splash,” which runs over the adjoining grandstand and rises on one side of the building, creates a wave-like effect,. CTBUH C CTB CT TBU TB UH H Jo JJou Journal ou o urna rn rn naal | 2011 20 011 11 11 Issue Isssue Is Iss su ue IIII ue. “In sophisticated urban planned environments, security should be subtle, but allow for the potential for heightened threats. The key is to find a suitable balance between security and preserving the designer’s vision. A security program for any structure should employ a variety of controls to deter, delay, detect, deny and respond to threats, as well as mischievous or potential accidental acts.” This paper emphasizes the importance of integrating security programming into building design, allowing for different uses and threat levels for the life of the building. Security strategies will be evaluated that can be applied to any building, as well as review procedures to address concerns early in the design process, especially in politically and economically charged international environments. General concepts and approaches to building security will be examined, demonstrating the benefit of collaboration between architects and security professionals at an early stage to meet the project’s goals without detracting from the planner’s vision for the project. The “Fortress” To the untrained eye, this graphic (see Figure 1) may appear “fortress” like. However, in its most basic format, the diagram describes the security program for building at any security level. Early dialogue between security professionals and the designer can limit the fortress or bunker aesthetic by careful placement of technical security, including cameras, setbacks, gates, fencing and spatial provisions for security staffing. In many cases, consideration is not given to the potential for a future modification to the building, such as the addition of a casino, parking garage, skate park or theater, which may increase the potential for malevolent acts. The addition of new tenants, such as a dignitary or VIP, may require a change in the security status not considered in the original design process. The modification of the physical and architectural security component is the most important, most expensive and, therefore, most difficult to modify post-design. Done early in the design process there is significant indirect and direct return on investment that can be achieved by preplanning.. When planning a facility, design professionals need to think outside-the-box. Although fear of terrorism typically drives the mindset for iconic building security, there are other more likely threats, including workplace violence, domestic spill over issues, intellectual theft, property theft and other malicious acts against persons or property that can affect the building and its occupants. Unforeseen dangers can create significant security challenges for building owners post-design and may detract from the marketing, image and status of the project. Planning for a single threat may not be effective and may miss potential threats in the future. The best approach is to create generalized controls designed to address a broad range of threats. Unlike other building elements, there are no standards for the provision of security based on building occupancy. As a result, the evaluation and development of security controls is purely based on a quantitative risk and consequence analysis which evaluates all aspects of the proposed building, not simply such critical assets as electrical and telecommunications systems. Conducting a risk and consequence analysis will assist the. 18 | Securing Iconic Structures. 32. The construction also adopted a variety of leading-edge approaches to create the desired result, including:. • Asymmetric shape – no two rooms are the same (see Figure 2); every single pane of the 12,500 panes of glass on the façade is a different size although each pane is triangular • Floor plates change shape and orientation to create the distinctive “overhang” moving from “curved triangular” to “curved rectangular,” while increasing in overall size and migrating from east to west as they progress up the tower • Capital Gate is one of few buildings in the world that use a diagrid structure; it also features two diagrid systems, an external diagrid defining the tower’s shape and an internal diagrid linked to the central core by eight unique pin jointed structural members. • All 8,250 steel diagrid members are different thicknesses, length and orientation ®. Figure 2. Typical hotel floor plan © ADNEC. CTBUH Journal | 2011 Issue II. Capital Gate, Abu Dhabi | 13. CTBUH Journal | 2011 Issue II. designer with understanding the exposure to threats. For example, a building near a proposed or existing mall will make criminal incidents more likely. In similar fashion, integrating a train or metro into a large high-rise project could increase exposure to chemical or explosive attacks, while the creation of a building near a government facility or embassy may escalate the tertiary terrorism risk. The type of building and its tenants may also affect risk rating, which can change over time. Understanding the risks early in the process will assist organizations in making decisions. The planner should ensure that the security analysis provides specific guidance and recommendations on vehicular access, security placement of cameras, access control and the overall security compartmentalization program. From a security perspective, designers need to think about the “what-ifs.” They need to have a vision. That does not necessarily mean implementing controls from day one, but designing provisions into the architecture so security controls can be easily and quickly adopted in the future if higher threat scenarios arise. The downside of shortsighted preplanning is evident in the airports built 20 years ago. The functions and usage of airports have changed dramatically. The free flowing public environment of yesterday is now a series of mazes and security compartmentalization. which could have been avoided, if only designers had taken a more open-minded approach during the design process.. Preparing for the Future To prepare for tomorrow’s uncertainties, today’s international planners should start by evaluating the site and potential setbacks and standoff distances from the façade of the building. Even with constricted site layouts, there are opportunities that can be explored. Setback can be achieved through a number of programming elements. To increase the affect of clear space, the perception of setback can be somewhat masked through architectural programming, such as the creation of multi-tiered planting areas, water features, structures and natural boulders. The proposed US Embassy in London employs an enveloped glass façade and a water feature to support security. The water feature provides a visual element to the project, but it also creates a defined perimeter and clear zone. When developing building placement, roadways should be carefully evaluated. Centralized or limited roadway access is preferred, while incorporating standards and requirements for emergency access. In some cases, emergency access roadways will need to be secured and may create a conflict with first responders. Proper signage and clear access routes can limit frustration by people who are not familiar with the site, which could. be a key to minimizing negative interactions with security. Site confusion can lead to anger. Roadways are integral to the project, but simple and cost effective techniques, such as using a serpentine access road, can create elegant and effective solutions to reduce the potential for a vehicle to approach a building at high speed. Counter terrorism and counter surveillance techniques are extremely beneficial to identifying an aggressor. For this reason, building layout, whenever applicable, should afford natural sight lines to allow the detection of an intruder. As a result, landscaping is extremely important. Trees and other foliage that can obscure sight lines should be discouraged. Lighting, the number one deterrent to crime, may become obscured by growing tree canopies. As a result, lighting plans and photometric should take into account tree growth over the life of the tree and the effect on the light distribution. By doing this more effective light placement can be identified. Hotels will often employ a porte cochere, which can expand setback from the primary structure while providing continuity in architecture and limit the perception of distance from the entry to the building. Setback is more than maintaining vehicle proximity, setback increases natural lines of sight as well as the area that must be traversed prior to accessing a facility, while supporting the potential for early detection of an aggressor. Designs should limit components that may be used by aggressors for criminal acts. Loose rocks of substantial size could be used to break windows to gain entry to a building or be picked up as a makeshift weapon in an ambush scenario. If rocks are integral to design, they should be kept small or be large enough that they can’t be easily picked up.. The Worst Case Scenario When designing setback and site placement, consideration should be equally afforded to the planning for emergency vehicles and muster points for evacuating tenants. Muster points need to account for the expected mass of people and should be as far away from ®. Figure 1. The “fortress” © Aon CTBUH Journal | 2011 Issue II. Securing Iconic Structures | 19. Developing Rotterdam’s Skyline. Frank van der Hoeven. Steffen Nijhuis. Authors Frank van der Hoeven, Associate Professor Steffen Nijhuis, Assistant Professor Delft University of Technology Faculty of Architecture Julianalaan 134 2628 BL Delft The Netherlands t: +31 15 278 9805 e: F.D.vanderHoeven@tudelft.nl e: S.Nijhuis@tudelft.nl www.graduateschool.abe.tudelft.nl. Frank van der Hoeven Prof. van der Hoeven is an associate professor of urban design at the Faculty of Architecture at the Delft University of Technology, the Netherlands. He conducted his PhD research in the field of underground space technology and multifunctional and intensive land-use. The core of his work deals with urban design issues related to mixed-use development: transit-oriented development, urban greenhouse horticulture, the use of underground space, high-rise urban areas and climate change. Currently he combines his associate professorship in urban design with the position of Director of Research of the Faculty of Architecture.. 54 Meet the CTBUH Kevin Brass. Features. The Concept. • Four hundred and ninety foundation piles were driven 20 to 30 meters underground to support the structure and counter stresses. The piles, which were initially in compression during construction to support the lower floors of the building, are now in tension as the stresses caused by the overhang have been applied.. Securing Iconic Structures. t + 86 21 6032 0100 f + 86 21 6217 8525 e: Stephen.Yas@mulvannyg2.com www.mulvannyg2.com. 18. By integrating with the National Day Grandstand – one of Abu Dhabi’s most historic structures – Capital Gate underscores the bond between the traditional and modern that is characteristic of Abu Dhabi’s developmental approach.. Figure 1. Typical section © ADNEC. Sean A. Ahrens, Practice Leader/Manager. Research. reflecting the building’s proximity to the water and the city’s sea-faring heritage.. Throughout history, a strong link has existed between iconic architecture and exhibitions. One of the best known examples is Paris’ Eiffel Tower, which was built as a visual symbol of the Exposition Universelle, World’s Fair of 1889. More recently cities like Seville have used powerful and innovative architecture as a way to highlight the cultural significance of their exhibitions.. 12 2 | Cap Capital pit ittaal ita al Gate, Gate aatte tte, e, Abu Abu bu Dha Dh Dhabi haab h habi bii. Authors. 12 Capital Gate, Abu Dhabi Jeff Schofield. “From the beginning of concept design, the architects and engineers integrated many passive and active sustainable systems into Capital Gate, its most visible sustainable feature is the “splash,” which twists around the building towards the south to shield itself as much as possible from direct sunlight.”. Steffen Nijhuis Prof. Nijhuis is an assistant professor of landscape architecture at Delft University of Technology (the Netherlands). His PhD research, entitled “Landscape Architecture and GIS,” focuses on the application of geographic information science in landscape architectonic research and design. The core of his work deals with theories, methods and techniques in the field of landscape architecture and urban design, visual landscape assessment and visual knowledge representation. He is leader of the architecture and landscape research program, series editor of RiUS and advisor to governmental and regional authorities in the Netherlands.. 55 CTBUH Organizational Structure & Member Listings. “The framework as presented carries the potential to underpin a city’s guidance on tall building development. This framework presents the context of a tall building design, providing a more balanced evaluation of a design proposal compared to studies that focus solely on individual tall buildings.” The planning and construction of tall buildings is often controversial, polarizing the public debate on architecture and urban life. In many cases the emotional discourse focuses on aesthetics and view corridors, more than city planning or economics. This paper introduces a framework that analyzes the visual impact a developing skyline has on a city and its surrounding region, using Rotterdam as a case study. By studying the height and completion year, identifying the tall building cluster as it is perceived visually and conducting a GIScbased visibility analysis, the framework provides context to tall building designs. The results make the assessment of individual projects more scientific and balanced, removing many of the emotional elements that often enter into the discussions. Introduction Research on the visual impact of tall buildings has the potential to make or break a tall building proposal. In the UK, debates over the appropriateness of projects in London and Liverpool are focused on view corridors, with UNESCO threatening to remove world heritage designations from historic complexes if the new developments damage their aesthetic impact (see “Debating Tall”).. Concerns about the appropriateness of tall buildings in the urban environment, the quality of the architecture and the impact on local real estate markets is increasingly reflected in municipal and metropolitan policymaking. Prominent cities with a longstanding tradition of urban management, building regulations and zoning plans often feel the need for additional instruments to control the development of what is described by McNeill as “an extremely complex spatial phenomenon” (McNeill, 2005). Scientific. literature, however, often neglects the substantial impact skyscrapers and their visual footprint can have on urban life. “The significance of these buildings – in terms of height, levels of human occupancy, aesthetic impact and popular representation and use – is in need of careful geographical interpretation.” (McNeill 2005) In 2007 the Netherlands Institute for Spatial Research (Lörzing et al. 2007) published an investigation on the visibility of the proposed Belle van Zuylen tower. At 262 meters the Belle van Zuylen tower would become Holland’s tallest residential building and the centerpiece of Leidsche Rijn, the new city district, west of Utrecht. But the Netherlands Institute for Spatial Research analysis showed that the Belle van Zuylen could be seen from most of the “Green Heart,” the semi-rural region enclosed by the cities of Rotterdam, Amsterdam, The Hague and Utrecht. The report was the last blow for the proposed development – construction was cancelled soon after the release of the report (Lörzing 2011). The Belle van Zuylen case is a fine example of using research for tactical purposes through the selective presentation of findings. The study did not present the Belle van Zuylen in its true context. The joint visual impact of all the tall buildings in the region on the Green Heart was not considered, nor how much that impact would change as a result of the construction of the Belle van Zuylen. If the study had included these elements, it may not have caused such stir. In fact, a nearby television tower, the 367-meter Gerbrandytoren tower, built 42 years earlier, dominates the visual impact of the area. A framework that helps to picture the context of a proposed tall building can potentially neutralize public and political debates that so often lead to polarization. This framework is based on three key elements: Rotterdam’s tall building development Rotterdam is one of the prominent European tall building cities with a mature tall building policy in place (see Figure 1). Several databases, including the CTBUH’s The Skyscraper Center, make it clear that only four. Figure 1. Rotterdam as a prominent west European tall building city © authors 30 | Developing Rotterdam’s Skyline. CTBUH Journal | 2011 Issue II. CTBUH Journal | 2011 Issue II. western European cities possess this type of mature skyline: London, Paris, Frankfurt, and Rotterdam. The leading position of Rotterdam is furthermore underscored by DEGW’s report on London’s Skyline, Views, and High Buildings commissioned by the Greater London Authority (GLA). The London policy document uses the same four European cities to compare established European practices of tall buildings policymaking: London, Paris, Frankfurt, and Rotterdam. The tall building policy document that emerged in the Netherlands is called hoogbouwbeleid or hoogbouwvisie. The Dutch policies resemble a number of policy documents recently produced in the United Kingdom and Germany. Height regulation is a key component of all these tall building policies. Height also translates into visibility. A modern history Over the years, the city of Rotterdam has carefully cultivated an image as a “city of architecture.” But “historic” architecture is not Rotterdam’s strong point. Few buildings were left standing after the bombing and fire of May 1940. The few buildings that survived were relatively modern buildings from the 1920s and 1930s. The city had to rebuild its center from scratch. Planners seized this opportunity to experiment with architecture and urbanism, which is why the Rotterdam city center now contains numerous monuments and icons from the modern and modernist period, sometimes referred to as “reconstruction architecture.” Discussions about the appropriateness of tall buildings surfaced from time to time, but never reached the emotional levels experienced in cities with a historic center. Tall buildings are now generally accepted and most are concentrated in the city center. While Rotterdam as a whole uses modern and modernist architecture to promote itself, tall buildings are an essential ingredient in the profile of the city: the skyline, including the famous Erasmus Bridge, has become the city’s iconic image (Ulzen 2007).. Rotterdam’s semi-official tall building history portrays a 100-year prelude from the late 19th century, with the completion of the 42-meter Witte Huis, built in 1898, to the so-called “first wave” of high buildings in the mid-1980s. Prominent city planners suggest that the city at the turn of the century was on the verge of a “second wave” of tall buildings, which would feature supertall buildings (Maandag 2001). However, this tale cannot be underpinned with facts. Neither the height nor the location of the high buildings dating from this early period relate to the municipal policy on high-rises. It was only in the 1970s that the current tall building area in the middle of the city center began to emerge. Essential data on tall buildings can be easily presented by means of a scatter plot. In the case of Rotterdam, the building height and the year of completion were plotted, including the primary use of such buildings. The beauty of Rotterdam’s scatter plot lies in the clear patterns that emerge. In her book Form Follows Finance, Carol Willis explains that the end of a tall building wave is typically marked by the construction of the “tallest building so far.” If we would consider these “tallest buildings so far” as anomalies and disregard them, the development of the Rotterdam tall building cluster is characterized by a remarkable continuity. However, if Carol Willis’ insights are applicable to Rotterdam, then the year in which the tallest building so far was completed could be used as the breaking points between tall building waves. Three such buildings stand out in Rotterdam: the Faculty of Medicine of the Erasmus University, also known as Hoboken (1969, 112 meters), the Delftse Poort (1991, 93 and 151 meters) and the Maastoren (2009, 165 meters). If the tall building history of Rotterdam is indeed characterized by waves, then these buildings are indicative of three such waves, as represented in the scatter plot (see Figure 2). The end of the wave is determined by the latest and tallest building in a development cycle. A first wave of tall building construction began in Rotterdam in the early 1970s and a second wave followed in the late 1980s and early 1990s. This second wave is not only defined by architectural height. The ® Developing Rotterdam’s Skyline | 31. “Although commonly classified as a typology of high-energy demand, tall buildings can be beneficial in hot, humid climates. Considering both urban and building scales, the typology enhances the exposure of the built form to wind flow, generates more wind at the ground level and provides desirable shadows upon the immediate surroundings. ” Suraksha Bhatla & Joanna Gonçalves, page 24. CTBUH Journal | 2012 Issue II. Inside | 3.

(3) Developing Rotterdam’s Skyline. Frank van der Hoeven. Steffen Nijhuis. Authors Frank van der Hoeven, Associate Professor Steffen Nijhuis, Assistant Professor Delft University of Technology Faculty of Architecture Julianalaan 134 2628 BL Delft The Netherlands t: +31 15 278 9805 e: F.D.vanderHoeven@tudelft.nl e: S.Nijhuis@tudelft.nl www.graduateschool.abe.tudelft.nl. Frank van der Hoeven Prof. van der Hoeven is an associate professor of urban design at the Faculty of Architecture at Delft University of Technology, the Netherlands. He conducted his PhD research in the field of underground space technology and multifunctional and intensive land-use. The core of his work deals with urban design issues related to mixed-use development: transit-oriented development, urban greenhouse horticulture, the use of underground space, high-rise urban areas and climate change. Currently he combines his associate professorship in urban design with the position of Director of Research of the Faculty of Architecture.. Steffen Nijhuis Prof. Nijhuis is an assistant professor of landscape architecture at Delft University of Technology, The Netherlands. His PhD research, entitled “Landscape Architecture and GIS,” focuses on the application of geographic information science in landscape architectonic research and design. The core of his work deals with theories, methods and techniques in the field of landscape architecture and urban design, visual landscape assessment and visual knowledge representation. He is leader of the architecture and landscape research program, series editor of RiUS and advisor to governmental and regional authorities in the Netherlands.. “The framework as presented carries the potential to underpin a city’s guidance on tall building development. This framework presents the context of a tall building design, providing a more balanced evaluation of a design proposal compared to studies that focus solely on individual tall buildings.” The planning and construction of tall buildings is often controversial, polarizing the public debate on architecture and urban life. In many cases the emotional discourse focuses on aesthetics and view corridors, more than city planning or economics. This paper introduces a framework that analyzes the visual impact a developing skyline has on a city and its surrounding region, using Rotterdam as a case study. By studying the height and completion year, identifying the tall building cluster as it is perceived visually and conducting a GIScbased visibility analysis, the framework provides context to tall building designs. The results make the assessment of individual projects more scientific and balanced, removing many of the emotional elements that often enter into the discussions. Introduction Research on the visual impact of tall buildings has the potential to make or break a tall building proposal. In the UK, debates over the appropriateness of projects in London and Liverpool are primarily focused on view corridors, with UNESCO threatening to remove world heritage designations from historic complexes if the new developments damage their aesthetic impact (see Debating Tall, page 5).. Concerns about the appropriateness of tall buildings in the urban environment, the quality of the architecture and the impact on local real estate markets is increasingly reflected in municipal and metropolitan policymaking. Prominent cities with a longstanding tradition of urban management, building regulations and zoning plans often feel the need for additional instruments to control the development of what is described by McNeill as “an extremely complex spatial phenomenon” (McNeill, 2005). Scientific. Figure 1. Rotterdam as a prominent west European tall building city 32 | Developing Rotterdam’s Skyline. CTBUH Journal | 2012 Issue II.

(4) literature, however, often neglects the substantial impact skyscrapers and their visual footprint can have on urban life. “The significance of these buildings – in terms of height, levels of human occupancy, aesthetic impact and popular representation and use – is in need of careful geographical interpretation.” (McNeill 2005) In 2007 the Netherlands Institute for Spatial Research (Lörzing et al. 2007) published an investigation on the visibility of the proposed Belle van Zuylen tower. At 262 meters the Belle van Zuylen tower would become Holland’s tallest residential building and the centerpiece of Leidsche Rijn, the new city district, west of Utrecht. But the Netherlands Institute for Spatial Research analysis showed that the Belle van Zuylen could be seen from most of the “Green Heart,” the semi-rural region enclosed by the cities of Rotterdam, Amsterdam, The Hague and Utrecht. The report was the last blow for the proposed development – construction was cancelled soon after the release of the report (Lörzing 2011). The Belle van Zuylen case is a fine example of using research for tactical purposes through the selective presentation of findings. The study did not present the Belle van Zuylen in its true context. The joint visual impact of all the tall buildings in the region on the Green Heart was not considered, nor how much that impact would change as a result of the construction of the Belle van Zuylen. If the study had included these elements, it may not have caused such stir. In fact, a nearby television tower, the 367-meter Gerbrandytoren tower, built 42 years earlier, dominates the visual impact of the area. A framework that helps to picture the context of a proposed tall building can potentially neutralize public and political debates that so often lead to polarization. This framework is based on three key elements: Rotterdam’s Tall Building Development Rotterdam is one of the prominent European tall building cities with a mature tall building policy in place (see Figure 1). Several databases, including the CTBUH’s The Skyscraper Center, make it clear that only four. CTBUH Journal | 2012 Issue II. western European cities possess this type of mature skyline: London, Paris, Frankfurt, and Rotterdam. The leading position of Rotterdam is furthermore underscored by DEGW’s report on London’s Skyline, Views, and High Buildings commissioned by the Greater London Authority (DEGW 2002). The London policy document uses the same four European cities to compare established European practices of tall buildings policymaking: London, Paris, Frankfurt, and Rotterdam. The tall building policy document that emerged in the Netherlands is called hoogbouwbeleid or hoogbouwvisie. The Dutch policies resemble a number of policy documents recently produced in the United Kingdom and Germany. Height regulation is a key component of all these tall building policies. Height also translates into visibility. A modern history Over the years, the city of Rotterdam has carefully cultivated an image as a “city of architecture.” But “historic” architecture is not Rotterdam’s strong point. Few buildings were left standing after the bombing and fire of May 1940. The few buildings that survived were relatively modern buildings from the 1920s and 1930s. The city had to rebuild its center from scratch. Planners seized this opportunity to experiment with architecture and urbanism, which is why the Rotterdam city center now contains numerous monuments and icons from the modern and modernist period, sometimes referred to as “reconstruction architecture.” Discussions about the appropriateness of tall buildings surfaced from time to time, but never reached the emotional levels experienced in cities with a historic center. Tall buildings are now generally accepted and most are concentrated in the city center. While Rotterdam as a whole uses modern and modernist architecture to promote itself, tall buildings are an essential ingredient in the profile of the city: the skyline, including the famous Erasmus Bridge, has become the city’s iconic image (van Ulzen 2007).. Rotterdam’s semi-official tall building history portrays a 100-year prelude from the late 19th century, with the completion of the 42-meter Witte Huis, built in 1898, to the so-called “first wave” of high buildings in the mid-1980s. Prominent city planners suggest that the city at the turn of the century was on the verge of a “second wave” of tall buildings, which would feature supertall buildings (Maandag 2001). However, this tale cannot be underpinned with facts. Neither the height nor the location of the high buildings dating from this early period relate to the municipal policy on high-rises. It was only in the 1970s that the current tall building area in the middle of the city center began to emerge. Essential data on tall buildings can be easily presented by means of a scatter plot. In the case of Rotterdam, the building height and the year of completion were plotted, including the primary use of such buildings. The beauty of Rotterdam’s scatter plot lies in the clear patterns that emerge. In her book Form Follows Finance, Carol Willis explains that the end of a tall building wave is typically marked by the construction of the “tallest building so far.” If we would consider these “tallest buildings so far” as anomalies and disregard them, the development of the Rotterdam tall building cluster is characterized by a remarkable continuity. However, if Carol Willis’ insights are applicable to Rotterdam, then the year in which the tallest building so far was completed could be used as the breaking points between tall building waves. Three such buildings stand out in Rotterdam: the Faculty of Medicine of the Erasmus University, also known as Hoboken (1969, 112 meters), the Delftse Poort (1991, 93 and 151 meters) and the Maastoren (2009, 165 meters). If the tall building history of Rotterdam is indeed characterized by waves, then these buildings are indicative of three such waves, as represented in the scatter plot (see Figure 2). The end of the wave is determined by the latest and tallest building in a development cycle. A first wave of tall building construction began in Rotterdam in the early 1970s and a second wave followed in the late 1980s and early 1990s. This second wave is not only defined by architectural height. The  Developing Rotterdam’s Skyline | 33.

(5) 1930. 1950. 1970. 1990. 2010 200m. KPN toren Space Tower. Maastoren 160m Delftse Poort. Erasmus bridge 2nd wave 120m Hoboken. building height. Euromast. 1st wave 80m. pre-wave 50m year of completetion white: residential or mixed-use high building black: non-residential high building dot: panorama/communication tower or bridge pillar. Figure 2. Scatter plots of the architectural height and the year of completion of Rotterdam’s tall buildings, without and with so-called tall building waves. Figure 3. Rotterdam, Weena Boulevard. The architecture dominated by the use of mirrored glass façade. The Delftse Poort (1991) is on the left. periods before and after 1989–1992 display many qualitative differences relating to tall building policy, architectural design, internationalization and the functional use of tall buildings. In 1993, the Rotterdam Municipal Council launched its first tall buildings policy (Hoogbouwbeleid) in a structured attempt to steer the development of tall buildings in the city (Dienst Stedenbouw + Volkshuisvesting 2000). The architectural quality of tall buildings from the era between 1969 and 1991 was dominated by the use of mirrored glass. 34 | Developing Rotterdam’s Skyline. façades (see Figure 3). Some examples of brutalism were built as well during this time. The Delftse Poort (1992, 93 and 151 meters) was the last design with mirrored glass façades. These styles disappeared, and the building designs became more diverse. The most prominent example of brutalism, the PTT Telecom building, a 51-meter tall tower built in 1970, was demolished in 2007, removing it from the skyline altogether. In a parallel development, foreign architects and internationally-operating Dutch architects became more involved in the design of tall buildings in Rotterdam. Until the mid-1990s, tall buildings were predominantly designed by local architects, with the exception of SOM and its three identical 95-meter tall Europoint towers built between 1975 and 1978. Since then, international architects have played a major role in tall building design in Rotterdam. The buildings designed by international architects include Murphy Jahn’s Fortis Bank (1996, 104 meters), Renzo Piano’s Toren op Zuid (2000, 96 meters), WZMH’s Millennium Tower (2000, 149 meters), Norman Foster’s World Port Centre (2001, 138 meters), Mecanoo’s Montevideo (2005, 152 meters), KCAP’s Red Apple (2009: 128 meters), Alvaro Siza’s New Orleans (2010; 158 meters), OMA’s De Rotterdam (2013, 149 meters) and the list is growing. The presence of these international architects is particularly felt in the design and construction of the tallest and most prominent buildings in the tall building cluster. Finally, there has been a marked difference in the use of tall buildings. Before 1990, the tallest buildings were office or university buildings. Many new tall buildings and proposals are now planned for residential uses (Klerks 2005). Figure 2 illustrates this clearly. Looking at the scatter plot, there is an interesting lack of buildings between the 110- and 120-meter mark, and a slight drop between 80 and 85 meters. Based on this observation we have identified in earlier research three distinctive height categories in Rotterdam (van der Hoeven 2004): a. above 120 meters; b. between 80 and 120 meters; c. below 80 meters.. Visibility of Rotterdam’s tall building cluster The visual appearance of the city’s skyline is determined by the size and the shape of the area where a cluster of tall buildings is developing. To determine the grouping a simple outline can be drawn that links the outer buildings considered part of the cluster (see Figure 4 and 5). If a new building is erected within the outline it will not change the width of the city’s skyline, regardless of the angle from which it is viewed. Any building erected outside the outline extends the skyline, as seen from a specific angle. In the case of most buildings it is clear whether or not they belong to the cluster due to their proximity to the other buildings. The current Rotterdam tall building policy assumes that tall buildings in the Central District, the Centre, the Nieuwe Werk and the Kop van Zuid are part of one continuous area. The question remains if the tall buildings west of this area, Park and Europoint, belong to the area that makes up the visual skyline. From some angles these buildings west of the center are visually part of the cluster and from other angles they are obviously not. A simple technique can be applied to visualize this. The area from which a building appears to be part of the cluster is determined by drawing two lines that connect the building in question with the two buildings that mark the borders of the cluster. If the angle between the two lines is larger than 90 degrees, then the area in which the building appears as part of the cluster dominates over the area in which it is visually separated from the cluster. Based on this method, it appears that the buildings in the park area should be considered as part of the cluster: Hoboken (1969, 112 meters) and the Euromast (1970, 185 meters). The three Europoint buildings are clearly not part of the Rotterdam tall building cluster. Adjacent to the clusters of buildings above 120 meters, and between 80 and 120 meters, a large number of buildings were built with heights ranging between 50 and 80 meters. All these buildings were reviewed to assess whether they are part of the cluster. A third outline is the result of this action. All three outlines are displayed in the overall map.. CTBUH Journal | 2012 Issue II.

(6) Central District. Central District. Centre. Centre. Erasmus MC Europoint. Erasmus MC. Nwe Werk. Eurasmus bridge. Europoint. Nwe Werk. Park Euromast. Figure 4. The 2015 multi-layered Rotterdam tall building cluster. True, the current tall building development within the overall cluster is driven by strategic projects such as the Rotterdam Central Station area development and the Kop van Zuid development. Standing within the cluster these two areas may appear as important sub-clusters. Looking from the outside however, it is almost impossible to visually separate them from the rest of the tall buildings, as illustrated by Figure 4. The profile differs significantly from the tall building zoning that ruled the development of tall buildings between 2000 and 2010 (see Figure 5). That original tall building zoning was based on traditional urban design concepts such as building alignment, setback principle, boulevard and “visual axis.” But using the visibility of the skyline as a means to identify the cluster suggests that the city could allow developments in a much wider area than originally envisioned in the city’s guidance on tall buildings.. GISc-based Visibility Analysis The visual impact of a single tall building was for the first time successfully reviewed (Lörzing et al. 2007; Lörzing 2011) in the case of the 262-meter Belle van Zuylen tower, proposed in 2007 near the Dutch city of Utrecht. The challenge faced in Rotterdam is more complex. In question is the joint visual. CTBUH Journal | 2012 Issue II. Erasmus bridge. Park Euromast. Kop van Zuid. Kop van Zuid. Figure 5. Map of the “official” Rotterdam tall building zones 2000–2010. impact of 130 tall buildings. In order to analyze and represent the visibility of the tall buildings in Rotterdam, a comprehensive GISc-based view shed method was applied (Rød et al. 2009; Nijhuis 2009; Germino et al. 2001; and Nicolai 1971). The accuracy of this analysis depends on the digital landscape model (DLM), and the rule for judging visibility (Fisher 1991, 1993; Riggs and Dean 2007). According to Riggs and Dean (2007), the average level of agreement which can be achieved is up to 85%. These findings suggest that it is better to express the analysis results in terms of probability (Fisher 1995, 1996). However, to achieve the highest degree of reliability, an accurate barrier model, or digital landscape model, was constructed consisting of a digital elevation model (DEM) in combination with topographic data. The basis is a high-resolution elevation model, the Actueel Hoogtebestand Nederland (AHN-1, 1997–2003), which is precise to about 15 centimeters per square meter. The location, architectural height and year of completion of the tall buildings were derived from the Emporis database (Emporis 2010) and added to the digital topographic map. The resulting digital landscape model was corrected using recent aerial photographs, field visits and street view imagery (Google Earth 2010). A number of key parameters influenced the result of the GISc-based viewshed analysis.. When examining tall buildings, the vertical size – specifically, the area of the façade – and weather conditions play a crucial role in prediction of probable visibility (Nicolai 1971). To put it more precisely, the visual range of objects in the landscape depends on (Duntley 1948; Middleton 1952): a. the apparent contrast between the object and its background b. the angles of the object c. its shape and vertical area d. the contrast threshold at the level of luminance (type of day) e. the conditions and technique of observing f. the eye level and related curvature of the earth (Duntley 1948) An important factor for determining the maximum visual range of distant objects is the meteorological optical range at different weather conditions. Observations from the Royal Netherlands Meteorological Institute (KNMI) show that the meteorological optical range by full daylight varies from nearly zero up to more than 10 kilometers (KNMI 2010). However, the average ranges of 12 kilometers (50% of the time), 20 kilometers (25%) and 28 kilometers (10%) are typical for Dutch circumstances (Nijhuis 2012; Nicolai 1971). For the analysis we calculated the maximum visual range of the tall buildings under . Developing Rotterdam’s Skyline | 35.

(7) different meteorological conditions by full daylight and involved vertical area (lengthwidth proportion < 5), vertical shape (rectangular) and contrast value (objectbackground ≥ 2 %). The cumulative view sheds from the analysis show the probable visibility at a meteorological optical range of 20 kilometers and takes into account the curvature of the earth.. Visibility buildings > 50 meters Full daylight: meteorological optical range 20 km (25% of the time) in relation to vertical size and area of the building. At a distance of 10 to 20 kilometers the human eye has problems observing a group of buildings as separate objects. The buildings tend to blur into one. So far we have not able to adjust the analysis to incorporate this effect. The GISc-based visibility analysis results show two important aspects of visual information with regards to tall buildings: visual coverage and cumulative visibility (Nijhuis 2009). The output is meant to be descriptive rather than normative. Visual coverage is about where you can see tall buildings in the open landscape; the cumulative visibility is about how many tall buildings you can see. Or, to put it differently, the results represent the intensity, or amount of tall buildings in the skyline of the city. The visibility analysis of Rotterdam’s tall building cluster reveals that their combined visual coverage reaches various places out of town at distances as far as 5 to 20 kilometers. Within the city large bodies of open water, including the river, harbors and lakes, offer similar opportunities to see many tall buildings simultaneously. However, in most of the city the skyline cannot be seen. Discussions on the visual impact of tall buildings should therefore make a careful distinction between the visual impact of the skyline on the cityscape and the very different impact on the landscape.. Development of the Skyline The accompanying maps show the visual coverage and effect of the tall buildings that are currently considered part of the cluster at vital moments in the development of the Rotterdam skyline: 1970, 1992, and 2015. Figure 6 shows the visual impact of all 130 current and future buildings over 50 meters. The next graphic illustrates specific selections. Figure 6. Visibility of all tall buildings in the municipality of Rotterdam. of these tall buildings, based on the outline of the tall building cluster and on the year of construction using 1970, 1992, and 2015 as thresholds (see Figure 8). The results indicate that the visual coverage of tall buildings outside the city was more or less established in 1970. Extending the Euromast, with the so-called Space Tower, to a height of 185 meters, contributes to this result. The cumulative visibility is getting “thicker” through the years. Tall buildings can be seen from more places inside the city, but outside the city the 1970 areas from where tall buildings can be seen does not seem to be growing. This implies that the 1970 skyline of the Rotterdam cluster was dominated by individual and small groups of singular tall buildings. Landmarks are likely to be weak references by themselves. Their. recognition requires sustained attention. However, in reality this usually does not happen. Attention is highly influenced by the angles of the building, as well as how far away it is, and how much it merges with the horizon. A slight increase of visual coverage over the years can be observed, especially north-west and south-west of the Rotterdam agglomeration, up to 1992 and onwards. However, the dominance of the cityscape. Figure 7. The Rotterdam cluster: visibility of the tall buildings built in 1970, 1992 & 2015. 36 | Developing Rotterdam’s Skyline. CTBUH Journal | 2012 Issue II.

(8) dramatically increased over the years and is expressed by the increasing magnitude of cumulative visibility of tall buildings. In recent decades the cluster effect of tall buildings in the skyline became the dominant factor in the visual impact. Starting north and south from Rotterdam in 1970 the visual accumulation of tall buildings in the open landscape developed into a city-embracing pattern in 2015. Although each new tallest building design faces public and political scrutiny, the fact is that the visibility pattern in Rotterdam is already established. Each new development has a decreasing impact as long it is confined to the established tall building cluster.. developments in a much wider area than originally envisioned in the city’s guidance on tall buildings. The visual coverage of the buildings that make up the current Rotterdam tall building cluster is roughly equal to the coverage of the buildings that were already in place in 1970. The skyline of Rotterdam has clearly become denser as a cityscape as many more buildings can be seen simultaneously in the surrounding territory. As a result each new development has a decreasing impact as long it is confined to the established tall building cluster. . The context for the development of tall buildings in urban areas can be effectively evaluated by analyzing the historical development in relation to the patterns that emerge from architectural height, year of completion, location in the city, and the functional use of the tall buildings. The framework as presented carries the potential to underpin a city’s guidance on tall building development. This framework presents the context of a tall building design, providing a more balanced evaluation of a design proposal compared to studies that focus solely on individual tall buildings. The mapped Rotterdam tall building cluster differs markedly from Rotterdam’s zoning that was in place between 2000 and 2010. This suggests that the city can allow. 1992. CTBUH Journal | 2012 Issue II. KNMI. 2010. Daggegevens van het Weer in Nederland 1951 t/m 2010. Metingenweerstation Schiphol: Meteorologischzicht. De Bilt. LÖRZING, H., A. HARBERS, AND M. BREEDIJK. 2007. De Zichtbaarheid van de Belle van Zuylen-toren. Den Haag: Ruimtelijk Planbureau. LÖRZING, H. 2011. “Visions of Belle van Zuylen.” In exploring the visual landscape.” In Advances in Physiognomic Landscape Research in the Netherlands, edited by S. Nijhuis, R. Van Lammeren, and F. Van der Hoeven, 303–15. Amsterdam: IOS Press (RiUS 2). MAANDAG, B. 2001. Rotterdam Hoogbouwstad (Rotterdam High-rise City). Rotterdam: Dienst Stedenbouw + Volkshuisvesting, OntwikkelingsBedrijf. MCNEILL, D. 2005. “Skyscraper geography.” Progress in Human Geography, 29/1: 41–55.. References Conclusions. KLERKS, J. 2005. ”New Metropolitan Living and the Skyscraper in a European City.” CTBUH Technical Paper. Accessed September 1, 2009. http://www.ctbuh.org.. DEGW. 2002. London’s Skyline, Views, and High Buildings, SDS Technical Report 19. London: DEGW Plc. DIENST STEDENBOUW + VOLKSHUISVESTING. 2000. Hoogbouwbeleid 2000-2010. Rotterdam. DUNTLEY, S. 1948. “The Visibility of Distant Objects.” Journal of the Optical Society of America 38(3): 237–49. EMPORIS. 2010. Commercial Real Estate Information and Construction Data. Accessed December 1, 2010. http:// www.eporis.com. FISHER, P. 1991. “First experiments in viewshed uncertainty: the accuracy of the viewshed area.” Photogrammetric Engineering and Remote Sensing 57: 1321–27. FISHER, P. 1993. “Algorithm and implementation uncertainty in viewshed analysis.” International Journal of Geographical Information Science 7(4): 331–47. FISHER, P. 1995. “An Exploration of probable viewsheds in landscape planning.” Environment and Planning B: Planning and Design 22: 527–46. FISHER, P. 1996. “Extending the applicability of viewsheds in landscape planning.” Photogrammetric Engineering and Remote Sensing 62 (11): 1297–302. GERMINO, M., W. REINERS, B. BLASKO, D. MCLEOD & C. BASTIAN. 2001. ”Estimating visual properties of Rocky Mountain landscape using GIS.” Landscape and Urban Planning 53: 71–84.. MIDDLETON, W. 1958. Vision through the Atmosphere. Toronto: University of Toronto Press. NICOLAI, J. 1971. De Visuele Invloed van Woonplaatsen op Open Ruimten. Met Enkele Toepassingen op het Midden van West-Nederland. Delft: Technische Universiteit Delft. NIJHUIS, S. 2009. “Het visuele landschap.” In Werkboek Bouwstenen Structuurvisie Noord-Holland 2040. Analyses en Verkenningen 3/3. Haarlem: Province of Noord-Holland. NIJHUIS, S. 2012. Landscape Architecture and GIS. Geographic Information Science in Landscape Architectonic Research and Design. Delft: Technische Universiteit Delft. (in preparation) RIGGS, P. AND D. DEAN. 2007. “An Investigation into the causes of errors and inconsistencies in predicted viewsheds.” Transactions in GIS, 11: 175–96 RØD, J. AND D. VAN DER MEER . 2009. “Visibility and dominance analysis: assessing a high-rise building project in Trondheim.” Environment and Planning B: Planning and Design 36(4) 698–710. VAN DER HOEVEN, F. 2004. “Te hoog gegrepen.” Rooilijn 10: 497–503. VAN ULZEN, P. 2007. Imagine a Metropolis, Rotterdam’s Creative Class, 1970-2000. Rotterdam: 010 Publishers. WILLIS, C. 1995. Form Follows Finance, Skyscrapers and Skylines in New York and Chicago. New York: Princeton Architectural Press.. 2015. Developing Rotterdam’s Skyline | 37.

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