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.
The driver’s compartment sits at one side of a platform measuring about 10 meters by 4 meters. In the middle are the four giant winches — each wound with thick steel wire cables — that control both the height of the jib and the hook that dangles from it. Straddling the whole platform are the two arms of the jib, which are held in place by two giant hinges.
The driver’s compartment is simple. A small room about 2 meters long by 1 meter wide, it has a seat — not unlike a bus driver’s — in front of which are three rotatable handles that control the crane. Floor-to-ceiling glass gives Ozawa a view up to the jib and down to the hook — when, that is, his view is not obstructed, which is most of the time. For that reason his cabin is also equipped with a small television screen, which displays a continuous video feed from a camera on the tip of the jib, pointing down. The camera, which can zoom in on the hook, is essential for positioning the hook and checking whether a load is secure.
“I can switch the TV on to normal television broadcasts during my breaks,” said Ozawa with a smile.
He also pointed out the air conditioner, saying, “The cabin is made of steel, so in summer it’s like an oven.” A small radiator at his feet helps keep the temperatures bearable in winter, too.
After 90 minutes of hoisting bits of steel into place, Ozawa has a 15-minute break, from 10 a.m. It would take about that long for him to get down to the ground, so he spends it in his seat.
The crane is not equipped with a toilet, but there is a funnel-topped tank, into which he can urinate. More serious toilet matters must wait until midday, when he comes down to the ground for another meeting and lunch.
In the afternoon it is more of the same. A 15-minute break at 3 p.m. punctuates four straight hours of essentially solitary labor.
Doesn’t he get lonely?
“Not really,” he said. “I’m in constant radio contact with the guys on the ground, giving and receiving signals about what to lift and when.”
Perhaps the second most important quality in a crane operator — besides being not afraid of heights — is an ability to work in a team.
“You need to be able to establish a rapport with the tobiko,” explained one of Ozawa’s colleagues.
It’s the tobiko, who are known in English as crane chasers or dogmen, that fix, or “sling,” the loads to the crane’s hook. (Tobi means black kite — as in the bird — which the workers were said to resemble when they used to jump between construction beams.) The tobiko indicate to the driver exactly where they want him to lower the hook by placing a bright orange witch’s hat on the spot before quickly wrapping each of two leads around the load when the hook arrives.
A quick “ko gohei” spoken through a helmet-mounted radio, is enough to inform Ozawa that the load is fixed and the hook or ko (child; the tip of the jib is called the oya, or parent) is ready to “go ahead” or be hoisted up.
How “go ahead” was shortened to “gohei” is anybody’s guess. The term for lowering the load also comes from English: “ko sura,” or “slack away.”
Despite their passing resemblance to indestructible anime robots, construction cranes are vulnerable to the elements. Wind speeds of more than 5 meters per second, heavy rain and even a hint of lightning are enough to have things shut down.
“I’m safe as long as I stay in the cabin,” Ozawa said when asked what would happen if the crane was struck by lightning, placing his faith (and life) in the effectiveness of the crane’s earthing wires.
The other danger is of course earthquakes. Toda Corporation has an earthquake-predicting device similar to the one used by national broadcaster NHK. If it detects an earthquake with a seismic intensity of more than 3, a warning is radioed from the company’s headquarters directly to its crane drivers.
“If you have time, you put the load down,” said Ozawa. If not, you ride it out — load and all.
And that means some serious swaying. While The Japan Times was visiting Ozawa atop his crane he was kind enough to deliver our cameraman’s equipment bag using his crane. As he swung the jib in so we could retrieve the bag from a wire net, the entire platform lurched forward before returning in a gentle sway.
“Every time you pick something up, the whole crane sways,” Ozawa said with a grin.
He nodded when asked if the swaying was worse during an earthquake. Any 3-plus temblor sees work stopped and the crane inspected before it can be resumed.
While cranes are themselves built to withstand a degree of swaying — whether it is load- or earthquake-induced — one of the skills crane drivers must master early on is the delicate art of stopping a load from swinging.
Every time a driver moves his or her jib, it causes the hook — whether it is laden or not — to swing naturally. If you’ve ever held a fishing rod with a sinker attached, you’ll get the idea.
Budding crane drivers are required to obtain special crane-driver licenses, for which they must pass government- mandated tests — and “swing stop” is one of the key skills tested.
It all comes down to being able to give the jib gentle flicks in the direction that the load is swinging — flicks that work to counteract the movement. Undetectable to anyone just watching the load, these shunts are essential, unless you want to turn a 10-ton girder into a demolition ball.
Skills like these are taught at schools such as the Tokyo Crane School in Katsushika Ward. One-week courses costing about ¥120,000 prepare students to sit the license examinations.
“A lot of our students just spend the day practicing swinging and stopping the load,” explained school instructor Koji Sato.
The tuition also covers instruction on government regulations regarding safety and crane operation, as well as a sizable dose of physics; there are lessons on everything from machine circuitry to the calculation of maximum loads using just the crane’s dimensions, engine size and cable diameter.
With crane driver salaries starting from between ¥250,000 and ¥350,000 per month, the lessons are popular, and Tokyo Crane School takes up to 500 students each year.
There are two types of crane licenses, those for mobile (generally truck-mounted) cranes, and those for fixed cranes. Climbing jib cranes, like the one used by Ozawa, are classed as fixed.
Which brings us to the vexing question of how, exactly, these cranes “climb” up to the top of buildings.
For the Shibaura site, Ozawa is using what is known as a “floor-climbing” crane. Once the Meccano-like building frame has been assembled around the crane to a height of six floors (just below the height of the crane’s body), the crane begins a caterpillar-like ascent. At the fifth floor, horizontal legs are shot out from either side of the mast. Attached to the building’s floor beams, these are then used as feet from which the mast pulls itself upwards using internal motors. When the base of the mast reaches the fourth floor — like a wine cork almost pulled from a bottle — it shoots out another set of horizontal legs, which latch on to beams there. By that time, the crane’s 30-meter mast is jutting up above the building and is ready to assemble another four floors. The upward crawling process, which takes about two days, can be repeated indefinitely, taking the crane up hundreds of meters.
The highest Ozawa has gone in a floor-climbing crane during his 15-year career is about 170 meters — at an apartment building in Minato Ward.
“You just have to get used to the heights,” he said.
The cranes that can be seen clinging to the sides of buildings are called “mast-climbing” cranes. They are able to add extra sections to the tops of their masts, and then climb up those — like an acrobat adding chairs to a chair tower he or she continues to scale.
Ozawa says he likes going back to see the buildings he’s made. “It’s satisfying to see them in use,” he says.
But before that can happen, it’s necessary for him and his fellow workers to pull one last trick from their sleeves: getting the crane down.
“I thought you’d ask that,” said one of Ozawa’s colleagues, as we talked in an on-site meeting room.
The construction crane — left apparently stranded on the top of the near-completed building — first pulls a smaller crane up to the roof beside it. In Shibaura, this will be a 100 t-m crane. Ozawa’s original 230 t-m crane will be dismantled and lowered to the ground by this smaller version piece by piece. When this is done, the 100 t-m crane will hoist up a 50 t-m crane, which will then lower down the pieces of the dismantled 100 t-m crane.
All very well, you say, but how do they get the 50 t-m crane down?
“We dismantle it and take the pieces down in the building’s elevator,” said the same colleague with a grin.
Ingenious! But, surely it would be quicker if Captain Kei Ozawa just flicked a special switch and launched the crane into the air, whence it would cruise into orbit to await the day when it would again be called on by mankind to, well, build something.
In a time of both misinformation and too much information, quality journalism is more crucial than ever.
By subscribing, you can help us get the story right.