City Expansions and the Vertical Urbanization approach

Cities have always attracted people with it’s vibrance, energy, and most important — opportunities. This has always put tremendous pressure on the city’s resources leaving no option for it but to expand. A city has three options — expand horizontally, build new cities, expand vertically. Each approach has it’s pros and cons. Let’s discuss this in more detail.
Expanding horizontally from it’s epicenter has been the basic nature of city’s growth. Back in 1898, New York expanded to become today’s Greater New York, a 5 borough mega-city. Cities in India such as Delhi, Mumbai expanded to create New Mumbai, New Delhi and so on. This expansion method has always enforced an upper limit on the city’s population. In 200 AD, Rome was able to grow and sustain up to 1.2 million citizens. Today, the number of residents in Mumbai and New York are about 21 million, Shanghai about 23 million. Almost all big cities have saturated to this threshold. Tokyo engulfed it’s suburbs and had a population growth to about 37.8 million residents. 27 million of these residents are in the surrounding suburbs. This tells us a city has scope to expand but would always saturate at an upper limit.
The second approach of growth is to build new cities. Morocco’s Zenata program is evidence of building such new cities, smart cities around citizens and their needs. This approach is to seed in a new town that not just has homes but also universities, hospitals, jobs, amenities etc. This project helps two populated cities in Morocco — Casablanca and Rabata a room for expansion, a room that is well planned and thought through. This approach though very high on investment if carried out carefully could result in a very sustainable and smart city. The Urban Planners would have the liberty to take best decisions that would have long lasting impacts.

And now the third expansion approach, Vertical Urbanization. If geography supports, city has room to grow vertically up. China is the best example here, one who has aggressively adopted this approach to manage it’s growing cities. Each year 25 million of it’s rural population are migrating to the cities. There are now over 160 cities in China with a population of over 1 million, according to China Today. To understand with reference point of view, US has about 10 cities with population of over 1 million. To manage this rate of growth, China has started building “vertical cities”. Today, China has the largest number of tall buildings in the world, surpassing US. It has more than 1,500 building above 150 meters and 26 supertall skyscrapers.

American firm, Gensler has designed the Shanghai Tower, the world’s second-tallest building by height (behind Dubai’s Burj Khalifa). This spiraling building takes the amenities of the horizontal city block — homes, shops, offices, galleries, multiplexes — and stacks them on a vertical plane. It is constructed with advanced reinforced glass with a high tolerance for shifts in temperature, that insulates humidity and has 8 vertical sky gardens. Taking advantage of it’s 2,073 ft mega tall height, Shanghai tower has 1,200 vertical-axis wind turbines capable of generating up to 350,000 kWh of supplementary electricity per year.

So these three approaches tell us how the cities have grown in the past and continue to grow in today. And we have to consider livability and sustainability in our planning to ensure success in the long run. Which approach is best suited for which city depends on its geography, governance, transport infrastructure, real estate and many other factors. If mega tall buildings are planned we need to ensure they have sky gardens and equivalent of city parks as well as wind turbines and solar panels for green energy. We have the choice to make the near future cities more sustainable, resilient and livable.

Reference — 
https://www.theguardian.com/cities/2014/oct/30/china-obsession-vertical-cities-skyscrapers-urbanisation-megacity
http://du.gensler.com/vol6/shanghai-tower/#/vertical-urbanism