Luffing jib cranes from the German company Liebherr-Werk Biberach are playing a central role in the ‘space race’ in Dubai, enabling work to be carried out effectively and speedily on sites where there is little or no room for tower cranes to operate.
Much of the construction work within Dubai city – where numerous major projects are under way both in the new and old areas – centres around working in highly confined spaces, while managing relations with neighbours and ‘just-in-time’ logistics.
This is where the Liebherr luffing jib cranes come of use, for their innovative design allows them to operate with maximum flexibility and reliability. Some of the landmark projects where these cranes are currently being used in Dubai are the Golden Sands Tower and the Damas Tower.
Golden Sands Tower
Two Liebherr 112 HC-L luffing jib cranes are at the heart of Golden Sands Tower, a 41-storey hotel apartment block project located on Sheikh Zayed Road. The structure, which is another six storeys away from reaching its design height, is scheduled for completion in early 2007.
For the project manager, Nashat Louis, of main contractor Al Shafar General Contracting, the luffing jib cranes are part of the solution to the very tight constraints he faces in terms of space.
“Site access is not easy at all,” he says. “We have to operate in a small space with no ground yard and everything has to be brought in on a ‘just-in-time’ basis from a busy road. When we have completed the tower, we will face an even bigger challenge in using a large area of the space that we do have to build the multi-storey car-park.”
With occupied residential blocks situated very close on either side of the site, and an upmarket hotel close-by, work is restricted to from six in the morning to six in the evening.
Al Shafar crane engineer, Anton Wanis feels that the cranes have performed the job they were brought in to do on this project. He says: “These twin cranes are the vitally important part of the job and the only way to carry it out, when you have just 60 m between the two neighbouring buildings.”
Concrete is pumped from the ground and the cranes are used to handle all materials – from concrete for internal columns to steel, fixtures and fittings. Able to slew through 360 degrees with a load at a radius of just 8 m, the cranes are able to overlap, increasing their flexibility.
The cranes need to be raised every 10 m or three floors, and for this a trio of 2.5-tonne saddle beams are used: one on which the cranes sits and a second higher-up to hold it steady. The third saddle beam is available to be installed in preparation for lifting the crane.
Raising the crane takes just over a day: 24 hours to disengage the saddle beam and about three hours to lift the crane, a job carried out by the second crane.
Wanis has a 12-man team dedicated to crane operation. He is already looking ahead to the completion of the Golden Sands Tower project and decommissioning of the two luffing jib cranes, the final act in the logistical exercise to beat the space issue.
He is already in the planning stages of what he feels will be a very difficult job. Two derrick cranes – one large and one small – will be hauled into place. The large crane will lower the luffing jib cranes to the ground. Then it will be disassembled and the smaller crane used to lower it down. Finally, the small derrick crane will be dismantled and brought to earth via the site passenger lift.
Jumeirah Beach Residence
Wanis – who is responsible for a second construction project, a four-tower job on the Jumeirah Beach Residence (JBR) – says that effective operation in a confined area is not the only reason for going down the luffing jib crane route. At the JBR project, craning operations are split 50-50 between four tower and four luffing jib cranes.
“We have four external cranes and four internal climbing cranes and here the main issue is one of cost,” he said, “The internal climbing cranes were used because we can make a very big saving on costs.”
Liebherr cranes are also being used on one of the last plots to be filled in along Dubai’s Sheikh Zayed Road: the Damas Tower. The project calls for the construction of two towers, each 45 storeys high and containing 447 flats, and is scheduled for completion in 2007.
Work on the first tower began eight months before the second phase of the programme started using a Liebherr tower crane for lifting. The second, however, was constrained by space limitations as the site is situated between the first Damas Tower and an existing block, with just 50 ft clearance either side.
“It’s the same everywhere in Dubai construction now: space is a really important issue,” says Sami Ahmed Khalil, projects manager with main contractor Bin Zayed Contracting.
“We were alright with a tower crane on the first tower, but space restrictions meant that on the second, we had to use a luffing jib crane.”
A Liebherr 112 HC-L luffing jib crane was ordered for the project through local distributor Inma. According to Khalil, these are being specified for their ability to operate in very confined spaces.
With a steep luffing jib angle (15 to 70 degrees) these cranes are able to avoid on-site obstruction with other working areas and slew through 360 degrees under load at only 7 m slewing radius.
He adds “This type of crane is important in Dubai, as being able to work in very confined spaces and has become a deciding factor for us all.”
The project used raft foundations and the concrete work is carried out in-situ. The single luffing jib crane is used to lift all materials, he says.