Demag AC 500-8 erects tower crane in Stuttgart

20 June 2018

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You would be hard-pressed to find a place in Germany that is as busy and congested as the area around the main train station in Stuttgart. And that is exactly where Bietigheim-Bissingen-based crane service provider Wiesbauer had to erect a 90m-tall top-slewing tower crane for construction company STRABAG-Züblin and STRABAG-BMTI.

For the challenging project, Wiesbauer decided on its Demag AC 500-8 all terrain crane. Reasons included its compact design and associated maneuverability.

Getting the eight-axle unit through downtown Stuttgart was a relatively relaxed affair, but accessing the work site behind the Landesbank Baden-Württemberg (LBBW) buildings proved to be significantly trickier. Wiesbauer project manager Marco Wilhelm explains why:

“The area where we needed to be, behind the high-rise bank building, could not be accessed by our heavy goods vehicles directly, as the official access road passes over a bridge with a 30t limit, which could not take carry the weight of our vehicles.”

An alternative route had to be found for the crane and lowbed trailers. A private tunnel used by Landesbank and Deutsche Bahn, which also led to the setup location for the tower crane, was the obvious solution. It meant that one of the busiest intersections in all of Stuttgart had to be closed briefly at 05:00, so that the crane, assist crane and the lowbed trailers would be able to pass through the tunnel against the direction of traffic.

Once the vehicles were at the site, the Demag AC 500-8 was able to demonstrate its ease of assembly: It took the team a mere six hours to set up the crane with a WIHI-SSL 60° configuration, a telescopic boom length of 51.80m, a 66m luffing fly jib, and 120t of counterweight. This made it possible for the AC 500-8 to reach the required hook height of over 104m and lift tower crane components, which weighed up to 13.5t, at a radius of 43m. The crane’s lifting capacity values at large hook heights and radii were crucial for the Stuttgart assignment.

Before the actual lifts to erect the tower crane, a smaller assist crane lifted the components off the lowbed trailers and set them onto the ground so that they could be pre-assembled. Then the Demag AC 500-8 took over the erection work as the main crane. It had a number of unique challenges ahead of it.

Since the tower crane had to be placed between two office buildings right next to the large glass façade of the LBBW high-rise, extremely high operating precision was required. On top of this, all the tower crane components had to be positioned over and beyond the high-rise and the jib had to be assembled over the high-rise as well—no mean feat for crane operators Karlheinz Moll and Steven Ziellmann, who also had to contend with the fact that there was a wall blocking their line of sight. They had to rely on their BMTI fellow team members to guide them by radio. “And the two high rise buildings provided wind effects that had to be included in our lift plans,” said Moll and Ziellmann. Both needed to stay extremely focused throughout the entire project.

Fortunately, their experience and the precise controls that characterize the AC 500-8 meant that they had the situation under control at all times and were able to complete the job on time.