The Wolff of complex heavy lifting

As a manufacturer involved in the rental business, Wolffkran is able to ensure product and service quality throughout the supply chain, from its factories in Germany to constructions sites around the world.

According to Martin Kirby, managing director, Wolffkran Arabia, this advantage enables Wolffkran to engineer crane systems cost effectively for the highest requirements of safety and efficiency by engaging with consultants and contractors in the initial stages of projects.

“We like to get involved in very challenging projects early on because we have the competencies to execute them. Over 100 years of experience in the tower crane industry has enabled us to guarantee 99.7% crane availability and uptime along with 24/7 support and service,” says Martin. 

“Longevity of equipment is very important in the rental business. We’re the only crane rental company in the Middle East that has ownership of the brand, which has advantages in terms of the technical support and service, quality control, and health and safety compliance. It’s common to see Wolffkran cranes operating around the world for over 30 years at a site. Two of Wolffkran’s 30-ton cranes, the 600EC models, have been operating near the Bahrain port every day for the last 25 years,” he adds.

Martin Kirby, managing director, Wolffkran Arabia; Dr. Mohamed Abouelezz, general manager, MENA and South East Asia, Wolffkran ISS; and Jeffrey Watson, operations director, Wolffkran Arabia.

One of Wolffkran’s specialties that’s gaining demand in the UAE is installing and operating cranes in tight spaces – close to towers, roads and metro lines, where the critical zone is narrow and safety is the primary concern. A current project in Dubai that reflects this expertise is the Museum of the Future. The project required free standing cranes because of the design of the building and its proximity to the Dubai Metro Red line where the critical zone is 5m.

“We’ve got decades of experience in engineering and operating cranes in confined spaces, usually very close to railway lines and roads. In Dubai, we’ve executed a lot of jobs beside metro stations, which helped build confidence with the Roads and Transport Authority (RTA). We believe we were chosen for the job because only we could offer a solution to operate high, free standing cranes at the site. We engineered the lifting systems cost effectively with complete control of the operation and without the pressure to offer cheap products or reduced service and support,” says Martin.

Wolffkran executed a twofold lifting plan for the Museum of the Future project, involving three tower cranes erected, swapped and jacked up in three different stages. As a crane solution provider, Wolffkran provided the base designs and method statement to erect and dismantle the cranes safely. Wolffkran also integrated the SMIE anti-collision system and handled the logistics involving mobile cranes in coordination with other divisions of Kanoo Group, specifically Johnson Arabia, which has been operating a fleet of mobile cranes for more than 20 years. Wolffkran employed its own in-house trained crane operators.

The first stage of the crane operations, which started in April 2017, had an initial crane configuration of three saddle jib cranes – all Wolffkran 6531.12 models with maximum load capacity of 12 tons – operating for the first six months.
For identification purposes, the three cranes were named TC1, TC2 and TC3.

The crane farthest from the Emirates Towers Metro station (TC1) had a jib length of 50m and height under hook (HUH) of 32.6m. The crane closest to the Metro station (TC2) was erected with a jib length of 45m HUH of 23.6m. The crane at the centre (TC3) had a jib length of 50m and HUH of 42.8m.

Wolffkran erected the three tower cranes in three days, one crane a day. The TC1 and TC2 cranes were installed on 2.5×2.5m bases, and the TC3 was installed on a 2.9×2.9m base. As Wolffkran’s crane bases are interchangeable among all its crane models, installing large bases, initially, enabled the jacking of the cranes as well as swapping the cranes on the same bases with progress in construction.

Jeffrey Watson, operations director, Wolffkran Arabia, says: “We employed smaller saddle jib cranes to create the concrete podium with 2–3 ton lifts. During the first stage, the smaller saddle jib cranes enabled us to lift with high speed and efficiency while saving power.”

The second stage of the crane operations began in October 2017 when the three saddle jib cranes were replaced with two 28-ton 355B luffing jib cranes (TC1 and TC2) and a 20-ton 8033.20 saddle jib crane (TC3). The TC1 and TC2 cranes had jib lengths of 50m and HUH of 45m. The TC3 crane had a jib length of 45m and HUH of 60.3m.

In the beginning of stage 2, the cranes lifted 11–12-ton panels. As construction progressed, they were jacked up to lift up to 20-ton steel parts. The cranes were operated for 20 hours every day, lifting between 9–15 tons of steel parts every hour.

“We swapped the cranes during the transition from stage 1 to stage 2 in less than 10 hours on a Friday by working in two shifts. So, it had a very low impact on the job. We jacked up the cranes gradually every three weeks to keep up with the rise of the building structure by coordinating with the project management team,” says Jeffrey.

From left to right: The 67.5m 355B luffing jib crane (TC2); 87.7m 8033.20 saddle jib crane (TC3), and 67.5m 355B luffing jib crane ( TC1) working on the final stage of the project. All the cranes have a jib length of 50m.

The third and final stage saw the HUH of the cranes increased gradually to 67.5m (TC1), 67.5m (TC2) and 87.7m (TC3). The jib of TC3 was extended from 45m to 50m. As the project nears completion for opening in 2020, the cranes are lifting material of up to 4 tons, and the Wolffkran Arabia team is evaluating various scenarios for dismantling the cranes.

Martin attributes this smooth operation to detailed project planning that evaluated all possible challenges from the beginning of project until its completion.

“We were thinking about dismantling the cranes before erecting them. Our method statement includes a detailed plan for dismantling the cranes after completion of the job. Planning the location of tower cranes should also take into account accessibility for mobile cranes for dismantling the tower cranes. If tower cranes are not designed and positioned correctly by anticipating the challenges of dismantling them after the construction is completed, the costs of dismantling them with mobile cranes will increase significantly,” says Martin.

Wolffkran Arabia ensured safety of the crane operations and safety at the site by employing the SMIE anti-collision system in addition to the in-built safety mechanisms on Wolffkran cranes. SMIE’s new generation of anti-collision systems, the SMIE ProSite, comes with new functions such as centralised visibility of global crane movement in real time, weather and crane activity history, remote bypass of anti-collision function, remote quarantine of out-of-service cranes, simplified management of zoning, and shared planning of crane activity. An LED touch-screen display gives the operator a comprehensive understanding of the working environment. Up to three anti-collision radio networks can be managed on a single system.

The SMIE ProSite anti-collision system is used to manage the three cranes and ensure job safety at the Museum of the Future construction site.

In addition to radio networks, the SMIE ProSite offers a secondary Wi-Fi network which enables site managers to manage crane settings from the site office or from a remote location via laptop or smartphone. The Wi-Fi network enables site managers to change settings of all cranes simultaneously and thus eliminates the need to climb cranes individually to change the crane parameters.

“The important requirement while using an anti-collision system, apart from preventing collision, is to prevent slowdown of a project. A reliable anti-collision system can improve both safety and productivity of a tower crane operation. It enhances the capabilities of a skilled crane operator, but the operator remains in control and acts as the first line of defence. We’ve found SMIE to be the most reliable anti-collision system, having used it previously in the UK. We’ve been using SMIE systems in the Middle East for the last two years,” says Martin.

A 355B luffing jib crane at ICD Brookfield Place.

Another field of expertise that puts Wolffkran in demand is erecting high tower cranes at later stages of construction, on the top of completed structures. An example is the Wolffkran crane installed on the podium of the 282m high ICD Brookfield Place tower under construction in Dubai International Financial Centre (DIFC).

Wolffkran was involved from the beginning of the project and started building a 355B luffing jib crane with jib length of 50m in June 2017. The crane set up for external climbing was erected from its base 25m below the ground. Currently, the luffing jib crane has a final HUH of 288 and is lifting loads up to 14 tons in the 1-fall configuration.

With increase in height of the crane during the last two years, it has been secured to the building with 14 tie-ins, each 18m apart. The highest tie-in is installed at 259.25m. The maximum load capacity, 28 tons, of the 355B crane will be utilised at the end of the project when the crane will be operated with a 2-fall configuration to dismantle another crane.

Wolffkran operates two 355B luffing jib cranes with jib lengths of 50m at the ICD Brookfield Place construction site. The crane on the left side has a final HUH of 288 from the ground level, and the crane on the right side has a final HUH of 256.5m from the podium. Both the cranes are lifting loads up to 14 tons in the 1-fall configuration.

In July 2018, Wolffkran Arabia was approached by the contractor to solve a peculiar problem. Steelwork on the backside of the building was lagging behind as the existing cranes couldn’t handle the increasing lifting requirements. The podium of the building had been completed 30m above the ground and the tower had risen to 150m. It was obvious that an additional crane was required.

However, there was no space available adjacent to the building to erect an external climbing crane. The time and space constraints also made in unfeasible to install an internal climbing crane. The only place left to install an external crane was on top of the podium floors, but the concern was whether it could handle the weight of a tower crane. It would require an engineering feat, one that Wolffkran was prepared to undertake having solved a similar problem on another project in Dubai, the Sky View Tower.

Wolffkran decided to use a second 355B luffing jib crane with jib length of 50m for the required load capacity of 14 tons. A steel grillage was constructed on top of the podium columns and 20 mast sections were erected on top of the steel frame before the first tie-in was installed at 80m. The slewing unit of the crane was installed at 90m. All these operations were achieved in five working days. Currently, the crane is at its final HUH of 256.5m from the podium.

The second 355B luffing jib crane at ICD Brookfield Place was erected by constructing a steel grillage on top of the podium columns. The first tie-in was installed at 80m, and the slewing unit of the crane was installed at 90m. The installation was completed in 5 working days.

“The conventional way of erecting a crane and climbing it gradually with several tie-ins would have increased time and costs, significantly. The need of the hour was to build a new tower crane to match the heights of the existing cranes and catch up with the steelwork. It took a lot of trust from all parties and we’re proud to have installed the crane and operate it within a week,” says Jeffrey.

Wolffkran Arabia is also busy at the One Za’abeel project where two 12-ton 180B luffing jib cranes and a 16-ton 224B luffing jib crane are being used to build the podium. All the three cranes have jib lengths of 50m and HUH of 54m. The free standing cranes were erected from bases 25m below the ground.

The company’s latest project is the Al Wasl Plaza at the Expo 2020 site where Wolffkran tower cranes are building the dome of the Plaza.

“Wolffkran is called on to handle crane operations in the toughest site conditions. That’s what brought us to the Middle East in the first place, when some of the top contractors in the region asked us to execute some very challenging jobs in 2007. We’re not in the race to have the largest fleet of cranes. We aim to be the top specialists for the most complex crane erection and heavy lifting operations,” says Martin.