Terex boom launch boon for Tokyo job

Undertaken by urban lifting specialists Human Ohya, the job involved the dismantling and lowering of a tower crane that was perched on top of a 70m-tall office building belonging to client firm Shimizu Corporation.

Apart from the safety concerns inherent in operating on the congested and narrow street where Shimizu Corporation is located, the main challenge was to conduct the lift quickly to limit traffic disruption, a task made tricky by Tokyo’s road regulations.

However to minimise disruption Human Ohya decided that the work could be completed in one day with the proper planning and the right equipment.

The company’s president Kazuhiko Ohya explained: “Due to our local road regulations, cranes cannot be driven with their boom on. Working in confined areas, it is often impossible to operate an auxiliary crane to help assemble the boom, so we are familiar with using a boom launch system.

“In addition, our team’s expertise in jobsite planning is paramount for a perfect synchronisation of the vehicles needed to transport the lifting equipment to jobsites in Toyko’s city center.”

On the morning of the lift Human Ohya drove the AC 350/6 to site, with its main boom, luffing jib adaptor, three jib sections, independent boom launch system, outrigger plates, secondary winch, counterweight hook block and part of the 75.1t counterweight needed for the job following behind on five trucks.

Firstly the truck carrying the boom launching system was moved into position before it’s four hydraulic stabilisers were deployed, raising it from the back of the truck.

Once at the required height, the truck was driven from below the boom launching system to make room for the truck carrying the AC 350’s main boom. The boom was then attached to the boom launching system using steel hooks that fit into to purpose-built slots on the boom’s outer casing.

After the AC 350/6 was driven under then attached to its boom, it self-rigged the rest of its 75.1t counterweight complement before the riggers fitted the jib adaptor and secondary winch, allowing the folding luffing jib system to be fitted at ground level.

“As the only system of its kind available, the Terex Easy Rigging System certainly makes a big difference,” said Ohya. “Avoiding work at height, it’s a great benefit to the safety of our team as well as making the job much faster and easier.”

Once fully set up the crane lifted the tower crane’s components, weighing up to 5t and up to 28m long, from 15m back from the roof edge down to ground level.

Ohya added: “We used a 48m luffing fly jib at 29m working radius with 75.1t counterweight during the dismantling process with the AC 350/6’s main boom deployed at 54.2m.

“In Tokyo there are many jobs that would not be possible without the use of a boom launch system, but the Terex Easy Rigging System was also paramount to completing set-up rapidly within our timeline in such a tight area.

“Thanks to its short slewing radius and compact outrigger spread, the AC 350/6 is just right in this kind of environment.”

The entire job was completed in under 24hrs.