Tokyo is one of the most crowded cities in the world and also one of the shortest on available land area. So how might this megalopolis develop in the future? The Discovery Channel recently aired a solution, originally conceived by the innovative Shimizu Corporation, which looks to ancient Egypt for an answer that, should it come to fruition, would require some Extreme Engineering.
The Tokyo Squeeze
According to studies conducted by the Tokyo Metropolitan Government the population of Tokyo has grown by 89,455 since 2002 and has currently reached a record high of 12,378,974 people, as of January 1st this year. Tokyo accounts for about 10 percent of Japan’s total population and has the largest population of any of the 47 prefectures. Interestingly however, Tokyo has a land area of a mere 2,187 square kilometers, which is 0.6% of the total area of Japan, making Tokyo the third smallest of the 47 prefectures. The 23-ward area has a population density of 5,613 people per square kilometer, making Tokyo not only the most densely populated area in Japan, but also one of the most inhabited areas per square kilometer in the world. Tokyo, quite literally, is bursting at the seams. Estimates for the year 2010 have put Tokyo’s daytime population at a staggering 29,000,000 and as the population skyrockets, Tokyo’s environmental state is set to degenerate commensurately. Anti-pollution acts have been fairly successful in regulating fuel-types for factory use and controlling exhaust emissions from gasoline vehicles, and thus environmental pollution resulting from carbon monoxide and sulfur dioxide has been somewhat stabilized. However reducing the average concentration of the contaminant by products of diesel engines: nitrogen dioxide, suspended particulate matter and photochemical oxidants has been largely unsuccessful. Coupled with this, Tokyo’s increasing volume of production and consumption is generating a burgeoning amount of municipal and industrial waste that intermediate and final treatment sites cannot cope with. Added to that, illegal dumping is on the increase and noxious pollutants from the waste are having an adverse effect on the environment.
As urbanization progresses in Tokyo, the greenery ratio regresses. Currently the greenery rate stands at 28% of the total ward area, but regular construction development and the reclaiming of land with surplus soil from construction sites, persistently encroaches on and shrinks natural land areas in Tokyo and further contributes to the phenomenon known as heat island. The heat island phenomenon involves rising temperatures around Tokyo and is caused by increasing energy consumption from urban activities and evaporating or decreasing water due to lost water surfaces and greenery. The city’s natural ground is being lost to towering monoliths and paved roads, the concrete and asphalt of which, when heated by solar radiation, also generates a great amount of radiant heat. For Tokyo to successfully accommodate the massive and imminent increase in urban population, in harmony with nature and the environment, an urban infrastructure renaissance of epic proportions would be needed, that goes far beyond the recent developments in Marunouchi, Shiodome, Roppongi and Shinagawa.
The Mega-City Vision
The Shimizu Mega-City Pyramid engineering concept first hit the drawing board in the early nineties. However due the recent broadcasting of the Discovery Channel’s “Extreme Engineering” program entitled ‘City in a Pyramid’, a tidal-wave of interest has once again been created in Shimizu’s inceptive vision. The Shimizu concept purports to address the aforementioned environmental problems in offering a detailed construction hypothesis that, if it were ever to make it off the drawing board and into Tokyo Bay, would be the largest engineering project ever attempted by man.
This three-dimensional city hanging within a pyramid shaped exoskeleton, would be 12 times higher than the Great Pyramid of Giza and on completion would peak at over a kilometer high, yet would appear to “float” on Tokyo bay. The Great Pyramid’s framework would include 55 smaller pyramids, each approximately the size of Egypt’s famed 4,500 year-old vestige. The City has been designed to facilitate residential living, industry and research as well as leisure and entertainment, within a self-sustaining environment, the actual construction of which would call for the use of some groundbreaking construction techniques, machines and materials, many of which will be world firsts. The sheer scale of constructing all sections of each facility would require robots, including humanoids, to be deployed as a pioneering auto-construction workforce – responsible for assembling the huge struts, trusses and overall segment assembly, from the seabed up. Automation of the construction process would be further facilitated by the use of uniform parts and materials – in theory Pyramid City could be the first city to essentially build itself.
All-in-all 1,000,000 people could be living, working and relaxing in this awe-inspiring creation within two dozen 80-story skyscrapers that would, conjecturally, hang on the inside of the pyramid’s skeletal framework, like peapods. 5,000 hectares of the gross developed area would be devoted to housing some 700,000 private residents. 2,400 hectares would be assigned to offices and commercial facilities, in which 800,000 people may be working at any one time. The remaining 1,400 hectares would be set aside for research, hotel and leisure establishments.
The perimeter of the City’s foundations above water level would be an incredible 2,800 meters and below the water 36 colossal cylindrical piers, driven deep into the seabed, would take the strain of Shimizu Corporation’s gargantuan edifice. Conventional engineering wisdom would be quick to suggest that the weight of such a construction, built using current materials, would simply disintegrate the foundations it was built on. The basic construction of Mega-City Pyramid would, in theory, be made up of hundreds of interconnecting octahedron units – each one 350 meters in perimeter. These units, the hollows shafts of which when combined in a tube-to-tube construction fashion, both vertically and horizontally, will permit expansion and enlargement of the exoskeleton and effectively allow the unrestricted construction of a three-dimensional space, as large as its particular function requires.
Each horizontal shaft would be 10 meters in diameter and 350 meters long and would house electrical and communication networks, commuter corridors and distribution networks, as well as two modes of transportation and observation windows. The diagonal shafts, each measuring 16 meters in diameter and 350 meters in length, would comprise plumbing and electrical networks, 2 elevator-esque transportation systems and a distribution network. The spherical nodes that would be located at the 55 points at which each octahedron unit intersects with another, would act as commuter transfer points and the 50 meter wide crystal glass globes would offer residents, commuters, workers and visitors an unrivalled panoramic vista of the bay area.
The engineering provisos would be however, that Mega-City Pyramid be strong enough to support the immense weight of the numerous interior skyscrapers and transportation networks, yet light enough to be supported by the 36 piers submerged deep in Tokyo Bay’s nadir. One possible solution to Mega City’s weight issue could be the introduction of carbon nanotubes as a primary building material. It was in 1991, when Sumio Iijima of the NEC laboratory in Tsukuba, used high-resolution transmission electron microscopy to observe carbon nanotubes, that this field really started to take off. Carbon nanotubes, as Iijima found, are made up of carbon atoms linked together to form tubes several nanometers in diameter (one nanometer is one billionth of a meter.) Carbon nanotubes are as hard as diamonds, durable and their tensile strength is 25 times that of most metal alloys available today. An ideal nanotube can be thought of as a hexagonal network of carbon atoms that has been rolled up to make a seamless cylinder. Carbon nanotubes are unique nanostructures with remarkable electronic, mechanical and strength properties. Interest from the research community first focused on their remarkable electronic properties, however as other useful properties have been discovered, particularly the disproportionate strength of the carbon material, interest has grown in potential construction applications. The vast array of struts, nodes, towers and piers that would comprisise Mega-City Pyramid could well be bolstered by nanotube technology, the overall weight of which would be 100 times lighter than if regular building materials were used for construction.
A Carless City
As envisioned by the Shimizu Corporation, there would be no cars, buses or trucks in this city and all modes of transport would utilize environmentally friendly forms of energy. Personal Rapid Transport pods, which are non-polluting, computer driven vehicles, will travel throughout the hollowed interconnecting trusses. This system comprises small lightweight cabins propelled by linear-induction motor (LIM) devices placed at regular intervals along the sidewalk. There would be 26 PRT lines running throughout the city at speeds of up to 40 km/h. The PRT’s would depart from the city’s access points or nodes at one-minute intervals and the system would effortlessly transport 190,000 people per hour around the various facilities.
Residents, commuters and visitors could also move through the city’s hollow exoskeleton via accelerating walkways, the access to which, as with all of Mega-City Pyramid’s transportation networks, being via the nodes. Unlike regular moving walkways, this system, in theory, would actually propel the passenger from a speed equivalent to that of a slow walk to jogging speed. As the horizontal footpads pass through the first turn, the geometry of the belt changes and commuters could be zipped along distances of up to a kilometer, ensuring that everyone would arrive at their appointment on time – if not a little wind-swept.
Sixty-four diagonal shafts would house an alternative transportation system called CCT (Continuous Circulatory Transport). This system is based on the common elevator, the difference being however that these elevators would not ascend and descend vertically, but rather would incline or decline along a diagonal gradient. These “inclinators” would have a maximum capacity of 50 people and could haul passengers at speeds approaching 40km/h. Commercial stocks and supplies, as well as regular post and other deliveries would be distributed throughout the city via another CCT system adapted for vertical and horizontal conveyance. The system would incorporate fully automated loaders at each node to facilitate the distribution of goods to their respective destinations, without the need for human intervention.
A Self-sustained Metropolis
Shimizu Corporation has placed a self-sustainable natural environment at the heart of its visionary proposition, perhaps in part because if an infrastructure the size of the proposed Mega-City Pyramid were plugged into Tokyo’s power grid, there would be blackouts across the nation, on a scale never seen before. For the Shimizu vision to be viable, due to the prodigious scale of the project, it would have to find the means to power itself. A number of ideas have been pitched by scientists the world over, including the possible use of huge fuel cells that would powered by hydrogen derived from algae. However the likely solution would most probably be an amalgamation of, for example, fuel cells and other environmentally conscious technologies.
The total power of waves breaking on the world’s coastlines is estimated at 2 to 3 million megawatts. In favorable locations, wave energy density can average 65 megawatts per mile of coastline. Located in Tokyo Bay, The City may well have to be equipped to convert waves to watts. Floating or pitching devices generate electricity from the bobbing or pitching action of a floating object. These objects could be mounted to a raft-like vessel floating in Tokyo bay or alternatively fixed to the City’s 36 sub-aqua piers. Other electricity-generating techniques could be incorporated, such as those that make use of the natural rise and fall of water that has been contained within shafts. The rising and falling water column drives air into and out of the top of the shaft, powering an air-driven turbine. Alternatively, a series of channels mounted on the City could be used to concentrate the waves, driving them into elevated reservoirs. Water flows out of these reservoirs and is then used to generate electricity, using standard hydropower technologies.
The entire exoskeleton of the pyramid could be coated with photovoltaic film to harvest sunlight for electricity. The huge crystal glass covered nodes could also serve as natural light source transmitters and by passing concentrated sunlight through optical fibers, these globes could efficiently bathe every corner of the City in natural sunlight. The City’s water could be recycled through on-site bio-reactors and these reactors could be powered by electricity generated from, of all things, garbage incineration.
There are no shortage of innovative design, construction and power-generating solutions for the Shimizu Mega-City Pyramid concept, of which many, although not immediately attainable, offer a fascinating insight into what might be waiting just around the corner for Tokyo and construction technology in general. Dr. Toshiaki Fujimori from Shimizu Corporation, who was interviewed on the Discovery Channel’s “Extreme Engineering” – ‘City in a Pyramid’ program said, “We’re not counting on building it right away, so in that sense it’s a dream. But by pushing this dream, we are pushing the progress of technology as well.”
J-Select wishes to thank the Discovery Channel, for their kind assistance with this article.
photos courtesy of discovery channel
Story by Jonathan Day
From J SELECT Magazine, June 2004