Building cities overnight

With a population of 10.3 million people in the city itself and an estimated 23.8 million in the wider metropolitan area, the region surrounding Seoul is second only to Tokyo as the world's most highly populated area. In fact the total population of South Korea is put at just under 50 million people, so almost half of the country's inhabitants live and work in and around the capital city.

But the real issue for Seoul is not so much the city's size, but how fast it is growing. South Korea has a very low birth rate for a developed country at less than 10 births per 1000 inhabitants-much less than the US at 14 births per 1000 and well below the world average of 20.

Its population growthis almost at a standstill, but internal migration from rural to urban areas means Seoul's population is rocketing. According to the Seoul Metropolitan Government a staggering 7845 people migrate to Seoul each day at present-equivalent to 2.86 million people per year.

This kind of explosive growthis of course having an impact on every aspect of life, and one of the key issues is simply having enough homes for everyone to live in. The city of Seoul itself is incredibly dense with more than 17000 inhabitants per square kilometre-about three times denser than Singapore.

One of the reasons for this is Seoul's rocky terrain-there are eight mountains within the city limits-which has forced it to be so closely packed, with the centre more or less on the low-lying land around the Hangang River. this rugged geology is also the major barrier to building more residential space in the city itself, and the solution has been to construct more and more homes outside the city limits in so-called ‘satellite towns’.

Despite being ‘out of town’, residential space in the wider metropolitan area still tends to be high-rise, again because of the mountainous terrain. The apartment blocks tend to follow a well-established model, with between 20 and 30 storeys above ground and several more underground floors for car parking. this formulaic, production-line approach means construction is fast, which it needs to be!

New town

One of the biggest current Greenfield developments is Seikyo New Town, about 40 km south of central Seoul. The project is being run under the auspices of the Korean national Housing Corporation (KNHC), the government agency responsible for redevelopment and improving living standards.

Since being set up in the early 1960s KHNC has built more than 1.6 million residential units, many in large new town developments. Seikyo New Town is also on a large scale. The total development will cover just over 19 km² and will provide housing fro several hundred thousand people.

The development is divided into four phases and work got underway at the end of last year on phase one. this in itself is an impressive scheme-a 3.2 km² site which will eventually have 3570 apartment buildings constructed on it, providing housing for some 100000 people. These buildings will be put up at a blistering pace-this part of the scheme scheduled to take just three years, with completion due in 2009.

Despite being selected for development, the greenfield site for the new town is undulating and rocky, with only a few metres of topsoil before getting down to Korea's hard granites and gneisses. this makes the site preparation work alone a daunting task, but when iC visited the scheme in September, this work was already well advanced.

Kumkwang Engineering & Construction started work in December last year on the contract to clear a 886000 m² portion of the 3.2 km² Phase One site. Valued at KRW 46.8 billion (US$ 50 million), the job involves moving a total of 4.15 million m³ of material, of this about 1.17 million m³will be re-used as fill material to level the site, while about 2.87 million m³ will be removed.

The remaining 0.1 million m³ will also be kept on site, with the intention of crushing it for aggregates when construction of the apartment blocks gets underway. When complete this package of land will provide housing for about 500 families in 16 blocks.

A spokesman for Kumkwang E&C said work was progressing well, although there had been a slight disruption with the discovery of several pieces of Bronze Age pottery on part of the site. Although work was suspended in a small area, the overall schedule had not suffered.

The excavation itself is being carried out by subcontractor Asia Equipment, which is using a fleet of 17 Volvo EC 460B 45 tonne class crawler excavators for this arduous work. The other major suppliers on the contract are Furukawa for the surface drills used in the rock excavation and Scania for the on-highway trucks used to move material both around the site to stockpiles and also to haul it away.

Although the 2.87 million m³ of ‘waste’ that needs to be disposed of is a massive quantity of rock and soil, there is a ready market for such material in South Korea in coastal land reclamation projects.

Asia Equipment has been on site with its Volvos since may this year, and according to a company spokesman, the work was running smoothly, with the machines able to cope with the rigors of the job. “The Volvo excavators are much better than the previous machines we were using, but they were quite old Cat 245s,” he said.

Private sector

Although the massive Seikyo New Town is a KHNC project, residential property development is by no means the sole province of Government agencies. iC also visited the Poil Apartments

Scheme further in towards Seoul in Anyang City. this scheme is being developed by GS Engineering & Construction, one of 10 or so major construction and real estate groups active in Korea.

Although smaller than the city-scale Seikyo scheme, GS's project is still on a huge scale with a blisteringly fast timescale. Over a 30 month period from May this year to November 2009 the company plans to build 40 apartment blocks, with homes for 2540 families on its 141368 m² site. With 25 stories each plus three underground parking levels, the development will have a net floor space of some 450000 m².

Again the terrain is rugged and rocky, and the schedule allows only five months to for the site preparation work, which entails excavating and removing some 1 million m³ of material. All of this will be sold to land reclamation projects.

The excavation work is being carried out by Young Jin Heavy Equipment, which is using its own fleet of 12 Caterpillar and Volvo 30 tonne and 45 tonne crawler excavators, augmented with two rented Cat D11 dozers and three Furukawa surface drills.

The schedule is such that the working day lasts 12 hours from 5 am to 5 pm, with Young Jin taking just one day off every two weeks to get the project complete. this is the key reason why the company uses only new machines-all the excavators on the Poil Apartments were less than one year old. According to a company spokesman, by using equipment that is still within its warranty period, downtime arising from maintenance and breakdowns is minimised. this means the key maintenance work for the company are fairly straight-forward daily tasks like greasing.

Future work

Following site preparation, the tower blocks will start to rise this winter. The favoured construction technique in Korea is to build a central concrete core with climbing formwork on top of piled foundations.