Vertical Cities in the Age of Hyper-Urbanization
Updated: Nov 24, 2020
by Joel Luna. Published in Technology Magazine, Asian Outlook on Engineering and Technology, by Asian Institute of Technology Solutions, November 2017.
The Urbanization Mega Trend
Rapid urbanization is a global mega trend. More than half of the world’s total population presently live in cities. The UN Report on World Urbanization estimates that by 2050, another 2.5 Billion will be living in Cities and 90% of this increase will be concentrated in Asia and Africa. People are flocking into cities by as much as 60 persons per hour in some countries such as India. And this tide of people moving into cities from the hinterland will continue.
A major reason for this is that cities, for all their flaws, generate economic productivity. Urban areas contribute as much as 80% of global GDP. The economic output is a result of the amplified level of productivity, creativity and efficiency brought about by the concentration of people and ideas. This level of productivity creates the attraction that pulls people from the hinterlands and find opportunity in the metropolitan areas.
This influx of people towards the urban areas creates tremendous strain on the city. The increase in capacity of the urban areas to service the rapid rise in population and economic activity is often outpaced by the level of urban growth. Often, the result of the mismatch is the rise of informal settlements, the insufficiency of infrastructure, over-congestion and a milieu of other city ills.
As people flock to the city, urban areas try to respond by increasing their capacity to absorb growth. Metropolitan areas have done this in a number of ways:
Suburbanization (expansion of the city into the countryside)
Land Reclamation (creation of developable land beyond the coastline)
Urban Infill development (utilization of undeveloped or underdeveloped parcels in the city)
Redevelopment/urban renewal (improvement in the capacity of built-up areas and/or improvement in an area’s productive output by a change in use or structure)
In an age of rapid urbanization, all the above interventions usually involve high density development, which typically translate as tall buildings, to offset rising land costs and to absorb increasing demand for built-up space. Even in suburban areas which have been characterized by low density, residential sprawl, pockets of mixed use higher density districts have emerged as alternative economic hubs to the traditional downtown.
Architects and urban planners have often envisioned cities composed of tall buildings as a way of housing their growing population. Often romanticized, tall buildings have triggered the imagination of visionaries and have actually led to inventions that have gradually enabled the realization of ever taller structures.
The Challenge of Tall Buildings
The Cost Challenge
Going vertical is often a reaction to scarcity of land, which translates to high land values. When unit building costs are less than unit land costs, it makes sense to build tall. But unit construction costs also tend to increase with each increment of height added to buildings. Thus, for any given site with a specific land value, there is a theoretical economic limit to building height, beyond which it may be more practical to simply buy more land than build taller. Theoretical, because land values are never static and they tend to increase over time. This combination of high land cost and high construction costs make tall buildings inherently expensive and beyond the affordability of the common citizens of the cities they belong to. The challenge therefore, in designing super tall buildings is in lowering the incremental cost as buildings get taller. Doing so will require innovations in structural design, vertical transport systems and mechanical electrical systems and regulatory controls that will facilitate progressively lower unit costs as buildings get taller. Perhaps inspiration can be gained from nature, and buildings can somehow require less materiality while increasing functionality even as the impact of gravity and wind increases as structures get taller.
Productivity and Resilience
High concentrations of people bring about the benefits of increased productivity, creativity and efficiency. Studies by Geoffrey West of Santa Fe Institute have revealed that cities exhibit super linear scaling where productivity and creative output increases exponentially as population and density increases. Even more interesting is West’s findings that per capita productivity also increases exponentially with population and density increase.
The flipside is that risks associated with urban agglomeration such as the spread of disease, crime, urban poverty, environmental damage and vulnerability to disasters, terrorist attack and social conflict are also compounded as population and density increases. History has shown, however that benefits have tended to outweigh these risks, and hence, cities continue to thrive through the ages. A major planning challenge is in addressing these risks and arriving at innovative measures that will mitigate and address the negative effects of urbanism without limiting the inherent capacity and potential of cities to contribute to the improvement and overall progress of society.
Inclusivity and Community
The tendency of tall buildings to be situated in expensive land and to be costly to construct raises a concern on whether tall buildings are just meant to cater to the affluent. A major criticism of suburban sprawl is the proliferation of single-use, gated enclaves that often cater to homogenous markets and income segments at the exclusion of the rest. Tall buildings often suffer from a similar flaw, often serving narrow, upscale markets in towers that are effectively gated communities tilted on their ends. If higher density is inevitable and verticality is the sustainable response to urbanization, then a true vertical city is one where its buildings are able to serve a good cross-section of society, where democratic and inclusive space can exist several meters above the street.
Even within the exclusive and homogenous domain of high rises, achieving a sense of community is also a challenge. Tall buildings offer limited opportunities for congregation, serendipitous encounters and the simple ritual of meeting neighbors that leads to the formation of extended social bonds that exist even in exclusive, gated communities. The concept of neighborhood or of community in the context of high rise living is yet to be defined. The mix happens at the street but not in the buildings. But if rapid urbanization will push people to live in ever taller buildings, then these future buildings will have to counteract the tendency towards isolation, loss of community and of social connectivity.
While vertical mixed use buildings offer a richer variety of uses compared to gated enclaves, the ultimate victory of a vertical city is when it is able to create socially-facilitative spaces within the buildings themselves in an interconnected fashion that foster the kind of community interaction that occurs naturally in the public streets and squares of many successful cities.
Signs of Hope: Elevating the public realm and emancipating the ground plane
A way to democratize the high-rise is if there is in finding a way to elevate the public realm, up within the floors of the buildings themselves. Attempts to achieve this include publicly accessible roof gardens, observation decks, building-integrated amenity spaces or the incorporation of civic uses such as museums, health clubs or libraries. Others attempt to offer cross-tower connectivity via elevated bridges as seen in Moshe Safdie’s Marina Bay Sands or in Surbana’s Pinnacle In doing, both in Singapore. With these elevated connections, the vertical city ceases to be simply a connection of unidirectional towers connected at the ground plane, (sort of a vertical cul-de-sac) and instead show the beginnings of a truly circulatable vertical mixed use development. All of these ideas could emancipate the ground plane, and allow the city to exist across multiple layered planes in 3 dimensions.
Innovative ideas from some architects such as WOHA, NBBJ, Ken Yeang, MVRDV and a few others proposed truly mixed environments within several floors of tower buildings, emulating the richness of fabric and activity in most cities. Numerous design explorations vertical agriculture using on multi-layered urban farms reframes cities to also become hubs of agricultural and not just commercial productivity. Dr. Ken Yeang likens the Vertical City as a row of urban blocks tilted on one end with parks, retail spaces, residential and office units in a seeming random patchwork that departs from the current practice of stacking single uses into a tower. Innovations in vertical transport will be necessary to handle not just the volume of people, but also to enable multi-directional mobility within buildings. As buildings become taller and denser, vertical transport will begin to take on the role of vertical mass transit. Already, ideas on vertical subways and magnetic levitation applied to elevators are being explored. Advancement in high capacity multi-directional elevator technology will enable the revolution in tall buildings, in much the same way that Otis’ prototype ushered in the era of the skyscrapers. Perhaps with the combination of structural design technology, vertical transport innovation and creative people-centric building design adopted to high-rises, a multi-layered city where 3-dimensional urbanism happens at multiple levels will be the next incarnation of the increasingly urban city.