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Black limousines inch their way along a narrow backstreet in Tokyo.
Their glossy bulk looks out of place as they squeeze between the electricity
poles and cramped bars, ramshackle wooden offices and tiny shops that line
the street. Then the limousines reach home. Above a broad marble staircase
and behind double plate-glass doors is a vast research complex with its
fashionable atrium and corporate brasserie dominating an extravagantly spacious
reception area. There are more such contrasts nearby. In a district dense
with dull apartments, a gleaming office block climbs above its neighbours.
A little farther away, a pair of blue-glazed buildings tower over the railway,
making even the passing bullet trains look shabby.

The same story could be repeated at least twice more across Tokyo. And
to any Japanese, the five names of these buildings’ corporate owners – Shimizu,
Taisei, Kajima, Takenaka and Obayashi – symbolise wealth and power. For
decades, they have been the biggest construction companies in Japan and
now they are among the wealthiest in the world. But these impressive buildings
are only partly a show of corporate status. They also demonstrate their
owner’s ability to refashion the environment. In keeping with their staggering
wealth, they harbour ambitious ideas for remaking cities, including plans
for structures that are larger than anything ever built on Earth.

Shimizu and Taisei have the wildest dreams. Shimizu has plans for a
gigantic pyramid that would stand more than 2 kilometres high. Its TRY
2004 building would occupy about 8 square kilometres of land and provide
offices and homes for a million people. Taisei goes even further with a
fantastic superskyscraper, known as X-Seed 4000 and shaped like Mount Fuji,
that climbs to 4 kilometres. But both these ‘cities in the air’ are so revolutionary,
that neither could possibly be built before the middle of the 21st century.

More interesting for the near future are the plans from Kajima, Takenaka
and Obayashi. Their structures may be quite small by Shimizu and Taisei’s
standards, but they will still be twice the height of the Sears Tower in
Chicago – currently the world’s tallest building at 443 metres. What is
more, there are no major technological problems to prevent them being built
soon. Kajima even claims that work could have started on its 800-metre building
if the Gulf War had not diverted so much money to the US.

Could plans for megabuildings like these eventually transform the
world’s biggest cities? The answer is, perhaps. Behind the Japanese desire
to build ever higher is some simple arithmetic. Japan is vastly overcrowded
and land prices there are the highest in the world. In 1991 the market value
of the whole country was calculated to be enough to buy the entire US and
all its listed companies, with plenty of cash to spare. In Tokyo, land prices
can scarcely be believed. In 1990 the plot of land where the Imperial Palace
stands in central Toyko was estimated to be worth more than the whole of
California. The result, explains Kisho Kurokawa, one of Japan’s most famous
architects, is that even staggeringly ambitious buildings employing highly
sophisticated engineering are still cheap. ‘Companies pay 90 per cent of
their money for the land and only 10 per cent for the building,’ he says.
‘No one cares if the building is expensive because it is a small part of
the cost.’

Japan’s construction companies are also well aware that Tokyo will not
be alone in being overcrowded and overpriced. Land prices in Hong Kong are
already heading for the sky, and even Bangkok is becoming expensive. By
the end of this century, 50 per cent of the world’s population will live
in cities and over 300 million people will live in 21 megacities, each with
a population of over 10 million. None of these cities will be in Europe,
but Tokyo, with a population of 28 million, will be the biggest of them
all and, quite possibly, the leader in providing the next century’s construction
techniques and urban architecture.

If Japanese companies do begin to draft the architecture of the world’s
megacities, then it will not happen tomorrow. Japan is in the middle of
a recession and it has a new government. Massive projects are on hold and
engineers researching futuristic building designs have had their budgets
cut. But demographic and economic forces are still on Japan’s side. Once
the stock market takes off again, international developers could be reading
the kind of hype to be found in Takenaka’s brochure. ‘We plan to create
a synthetic, yet totally comprehensive environment which will unite both
urban functions and nature with the goal of developing the vertical utilization
of urban space,’ it boasts, alongside pictures of its Sky City 1000.

Takenaka’s artificial city looks like a giant cooling tower as it climbs
1000 metres into the clouds. The plan is for 14 layers of self-contained
settlements that together accommodate 35 000 residents and 100 000 office
workers. Each storey contains a communal area in the centre, exposed to
wind and sunlight, and planted with natural vegetation. Around the perimeter,
rising 56 metres, is terracing for homes, shops and offices.

One advantage for the inhabitants of Sky City is that they would not
have to worry about earthquakes – the structure’s sheer mass makes it insensitive
to ground movements and wind, says Masato Ujigawa, chief researcher at Takenaka’s
technical research laboratory. But Ujigawa admits that the project may go
too far, too fast, for some people. The company may have to go ‘for a smaller
step first’, he says. ‘The concept is so unfamiliar that people just can’t
imagine what it would be like.’

Kajima offers a more familiar look. Its skyscraper – 200 metres shorter
than Sky City – will not use any unproven technology. ‘We’ve produced a
completely practical design,’ says Toshihiko Kubota, one of the project’s
senior engineers. And they weren’t taking any chances with the name either
– it’s called DIB-200, Dynamic Intelligent Building of 200 storeys.

The structure consists of 12 cylindrical modules 50 metres across and
200 metres long, which are stacked one on top of the other to form four
towers that rise to different heights from the corners of a quadrangle at
the base. One tower is two modules high, two towers are three modules high,
and the fourth tower consists of four modules and climbs the full 800 metres.
An unexpected advantage of designing the building as four towers is that
the gaps between reduce the wind loading on the structure.

The modular design is an engineer’s dream, helping keep down costs and
making technical problems more manageable. But the final design looks as
if it owes more to engineering pragmatism than architectural flair. The
two architects for DIB-200, Sadaaki Masuda and Scott Howe, an expatriate
American, are not disturbed by that criticism, however. Masuda admits that
they could do little to influence the overall appearance of DIB-200 once
the module had been designed and the parameters agreed. He believes his
company is right to want a technically feasible scheme that, however ambitious,
is realistic by today’s standards. Howe sees their contribution as helping
to make the building a pleasant place for a population equivalent to that
of a medium-sized town.

The first two tiers provide office space for about 50 000 people, on
the third tier there will be a hotel with 2500 rooms, while the top tier
is a residential block for more than 300 homes. Despite the structure’s
extraordinary height, Howe talks of ‘putting some horizontal into the building’,
of ‘artificial ground levels and no bottlenecks moving up and down the building’.
People will use high-speed lifts to shuttle between tiers, slower ones to
reach individual floors. Though Kajima is sticking with proven technology,
it is taking conventional lift design to the limit with cables as long
as 600 metres to provide the building’s most direct service. Between tiers,
horizontal ‘sky lobbies’ will link the towers, and contain shops, sports
and cultural centres.

Set alongside the solid, organ-pipe look of Kajima’s building, Obayashi’s
Millennium Tower truly looks like a building for the 21st century, elegant
and slender. The company signed up Norman Foster, the British architect,
in an effort to come up with a pragmatic design for a high-rise tower. Among
Foster’spast achievements is the Hong Kong an Shanghai Bank, sited in the
heart of the British colony, whose structural design in reinforced concrete
and steel dominates the building’s architecture. His work with Obayashi
adopts a similar approach.

Vertical city

Millennium Tower is a cone with its main supports exposed, climbing
800 metres above Tokyo Bay. A central core runs the height of the tower
and 12 helixes, braced by vertical girders, spiral its external surface.
The core and helical frame, both in steel, are linked horizontally at intervals
to provide what Keizo Shimizu, the project’s general manager, describes
as a rigid ‘tube-in-tube’ structure. The arrangement helps the tower to
resist the large forces generated by wind and earthquakes.

The floors that tie the two tubes together also enhance the structure’s
stability by transferring most of the building’s weight to the helical
shell, says Shimizu. Because this vertical load is thus distributed over
a wide area at the base of the cone, which has a diameter of 130 metres,
the building becomes even more difficult to budge. ‘It’s like standing with
your feet apart,’ he explains.

Restricting sway was an essential part of the design brief because the
tower is expected to accommodate 17 000 office workers and 2000 residents
on the 150 floors that make up its first 600 metres. The top 200 metres
is a communications pylon. Fast lifts, driven by linear motors, will shunt
people between ‘sky centers’, 30 floors apart. ‘It’s a vertical city,’
says Shimizu.

And if Millennium Tower looks as if it is poised for takeoff, Obayashi
will even be able to tell residents where they should be going – the Moon.

Although Obayashi ranks just fifth among Japan’s construction companies,
it has given its engineers and architects licence to think really big.
Their dream is to build Lunar City in a crater on the Moon. By 2050, it
is expected to be home for 10 000 people and a Mecca for tourists.

There will also be communal leisure centres where even confirmed couch
potatoes will be tempted to take advantage of the Moon’s low gravity and
try some physical exercise, assures Oba-yashi’s guide to the future. ‘Hang-gliders
can go a long way with just a little sprint. Man-powered aeroplanes are
a reality. And safe landings are guaranteed with the smallest of parachutes.’
If Japan’s construction companies ever start work on Lunar City, or any
of their futuristic buildings for the Earth’s megacities, a safe landing
is certainly something they will have to worry about.