Nikkei Business Online, one of Japan’s leading online business magazines introduced a construction site which is “floating” on Tokyo Bay -- the details of breakthrough construction of the 4th runway (called as Runway D) at Haneda Airport (Tokyo). Once ready, the airport can increase the capacity of international departure and arrival slots up to 60,000 times per year. Haneda will be capable to play an important role as one of major international airports near Tokyo, after Narita International Airport.

There were so much difficulties and limitations came up at the time of the planning the new runway, and that gave birth to "Hybrid Runway", which was the combination structure of landfill and steel jetty.

Why must have a part of runway constructed with jetty structure? The reason was environment consideration. A part of Runway D is touching to the mouth of Tama River; so if the base was completely landfill structure, it would have stopped the river flow. Jetty structure was the solution for protecting the nature.

Jetty consists of a myriad of steel pillars underneath and steel unit structures called “jackets” on them.

Depth of water in Tokyo Bay is about 14 to 19 meters and also, around 20 meters from under the sea is soft ground. To build robust jetty which is capable for supporting jumbo jet landing, steel pillars of 1.6 meters in diameter need to be hammered into 70 meters depth under the sea bottom.

Then “jacket”, weighs 1,300 tons, is placed on every set of six steel pillars. Width 63 meters, depth 45 meters and height 32 meters, a jacket size is equivalent to a 13 storage office building.

One of the most critical factors for steel-made jetty was "rust"; it should endure for at least 100 years in sea water. Various rust proof measures have been taken under jackets, such as covering with titan-made cover plates. These jackets are produced by Nippon Steel Corporation (http://www.nsc.co.jp/) and JFE Holdings (http://www.jfe-holdings.co.jp/).

Finally, 52 hectare extent of land has been created by enlinking 198 jackets, equivalent to 40 Tokyo Domes (baseball stadium). A road connecting terminal building and Runway D is also built with jetty structure and combining everything, 430,000 tons steel materials are used for this construction, which is equivalent to 100 Tokyo Towers!!

Total operating expenses required for this expansion work was one of the largest ongoing construction projects in Japan: 570 Billion JPY. However shockingly, provided construction period was just 41 months, almost a half of the period that usually this much size of project requires. There were Haneda Airport specific issues behind it.

The toughest challenge was "height limit" for the heavy machineries. Very next to the construction site of Runway D, there were live Runways A and C receiving jumbo jet landings once in two minutes at peak time. So the crane height was strictly controlled.

Construction work of Runway D continues 24 hours a day for 365 days. If the work completes according to the current schedule, the new runway will be on operation from October 2010.

Those who are interested in the construction site of jackets, please visit observatory facility available at the southern tip of Haneda Airport; jacket emplacement work is going to continue till February 2010 at 1 - 2 times in a week so if you are lucky, you will get very rare chance to eyewitness the moment “brand new land” is being created.

Based on Nikkei Business Online Magazine (Source: http://business.nikkeibp.co.jp/article/tech/20090806/201964/?bv)