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Sunday, May 11, 2008
Reaching from the skies
Anywhere in urban Japan you're likely to see a great orange crane looming over you. But how do they get up there; how do they get down — and what's it like to be at the controls?
By EDAN CORKILL
One of the classic images from Japanese anime — immortalized in the famous post-apocalyptic "Neon Genesis Evangelion" franchise — is of a child-pilot sitting at the controls of a robot that's so huge it stands head and shoulders above the surrounding buildings. It's the key to the genre's escapist allure — the means by which even the most wimpy of adolescents can believe that they, too, can take on the world.
I would be the last to suggest that 34-year-old Kei Ozawa is in any way like a child, but seeing this "crawling jib crane" driver in his control box perched some 30 meters above a half-complete building near Tokyo's Tamachi Station — and with only the horizon stretched out before him — that is the image that springs to mind.
Hit the wrong button, if you are Ozawa, and the whole thing might start walking down toward Shinagawa. Well, not quite — although surely the potential for disaster is almost as great.
What really goes on up there? The chances are everyone in this urban world has at some point gaped up at a high-rise building under construction, with its topmost crowns of orange- and white-striped cranes, and thought: "How do they do that?"
Actually, the questions that occur to us earthbound crane-viewers are so predictable it is surprising that construction companies don't hang giant "cheat sheets" from their vertical enigmas:
This crane got up here by etc. Its job is etc. Upon completion of its job, it will get down again by etc.
Interest in construction cranes has climbed to new heights of late, particularly at the Tokyo office of The Japan Times. It was only partly to do with the tragic collapses in New York on March 15 and Miami on March 25 that our fascination was fueled. In fact it started from lunch breaks spent watching cranes across the street, where a 47-story building has now quite suddenly reared up. That fascination only grew with walks from Tamachi Station spent regarding another huge construction site nearby, where it turns out that the man at the helm of its giant crane is one Kei Ozawa.
Ozawa works for the Toda Corporation, one of the larger construction companies and which dates back to 1881.
Toda has done its thing all over Japan — from the graceful sail-shaped Yokohama Grand Intercontinental in Minato Mirai to the Oazo Building in Tokyo's Marunouchi business district — and some overseas too. The right to design and construct a new building for the Shibaura Institute of Technology, near Tamachi Station, was won in a competition last year, and work began on the project in January.
Ozawa has been on-site from the outset, and will remain there till the end of June. (The building itself will be complete by December.) If anyone can be said to be single-handedly making this eight-story edifice, with a total floor area of almost 13,000 sq. meters, it's him. Or at least, it's him when he's in the cockpit of his Evangelion-like crane.
"My primary job is to lift the girders and beams into place," the native of Kanagawa Prefecture explained.
The new building is of steel construction, with a few areas using pre-stressed concrete. That means it very much resembles a giant Meccano set. Planted smack bang in the middle is Ozawa perched in his crane. Like a stork bending down to build a nest at its feet, he gets his crane to pick up girders and beams one at a time, lift them high and then hold them in place while three or four workers fix them in position.
"The satisfaction of this job is seeing a whole building sprout up, little by little," he said.
Jib cranes like Ozawa's have a single, straight arm (called a jib), capable of moving up and down from an almost horizontal position to an almost vertical one. This means that a crane can work at a variety of distances from its base, or mast. The higher you raise the jib, the closer the load comes to the crane's vertical structure. Add to that the ability to swivel through 360 degrees and you have a machine particularly useful for working in Japan's congested cities, where operators are frequently required to deliver girders to sites sandwiched between existing buildings.
"After about a year you get used to the controls and can deliver loads to within a few centimeters," Ozawa said.
The size of a construction crane is measured in a hybrid unit called a "ton-meter" (t-m), which is calculated by multiplying the operational radius of the jib by the crane's maximum load in tons. For example, when his jib is extended to a radius of 32 meters, Ozawa's crane can lift 7 tons (or approximately one double-decker London bus, when it's empty). If the jib is lifted to a radius of 20 meters, its capacity increases to 12 tons (the same bus, filled to capacity). A median is taken between those two ton-meter calculations (7t × 32m = 224 t-m and 12t × 20m = 240 t-m) to give the crane a "standard rating," which in this case is 230 t-m.
"It's one of the larger cranes we have at Toda," explained Ozawa.
But bigger construction cranes do exist. The largest jib crane in the world is rated at 1,500 t-m, and it can lift a whopping 20 tons at 45 meters (and 50 tons at 30 meters). Four of those giants, which are manufactured by Ishikawajima Transport Machinery (one of Japan's three leading makers — the others being Ogawa Seisakusho and Kitagawa Iron Works), were used to construct Japan's tallest building, the 70-story Landmark Tower in Yokohama.
While crane-making companies such as Ishikawajima have operations overseas (joint ventures in China are predictably popular at the moment), the cranes themselves tend to stay in the country where they are manufactured. This is partly because laws regulating cranes differ between countries. Earthquake-prone Japan has some of the strictest regulations, requiring that cranes can withstand shakers with a seismic intensity of just over 5. So if a builder was prepared to pay for the transportation costs, a Japanese crane could conceivably be shipped and used overseas. (They'd need to bear in mind, though, that a 230 t-m crane like that used by Ozawa is so big it is generally transported, in pieces, on the backs of 25 trucks.)
Space issues also influence crane preferences. Japanese construction companies prefer jib cranes for their maneuverability in tight spaces, while companies overseas tend to go for "horizontal" or "tower" cranes, which have fixed horizontal jibs, giving them the appearance of giant letter Ts.
A regular "day at the office" for Ozawa starts at 8 a.m. The crane operator joins in with five minutes of exercises with his fellow construction workers before having a series of 10-minute meetings about the day's plans.
By 8:30 a.m. he's climbing up the 30-meter ladder that takes him to the crane's operating compartment. The ladder is equipped with a pretensioning safety rope, which, when attached to a D-ring on his belt, is able to turn a precipitous fall into a 2-meter bungee jump.