Demag AC 160-5 lowers construction materials for Zervreila concrete dam

Fanger Kran AG tackles impressive job while surrounded by the High Alps

Anyone who has driven their car on a narrow and steep mountain road knows that this requires undivided focus and attention. So it should come as no surprise that doing the same but with a five-axle crane is a one-of-a-kind scenario that comes with extreme challenges for both operator and machine.

“That’s why we decided to use our Demag AC 160-5 for this job. With its extremely compact design and outstanding maneuverability, it was perfectly suited for the mission – both in terms of getting to the dam and of taking care of the corresponding work,” reports Fanger Head of Cranes & Transport Josef Waser. In addition, the crane had the power required to carry out the lifts at the Zervreila concrete dam in the Swiss canton of the Grisons.

Tunnels as the proverbial eye of the needle

Before that, however, the AC 160-5 had to be prepared for the multi-hour trip to the work site. For example, the counterweight base plate had to be removed in order to reduce the weight to less than 60 tonnes, which was necessary given the mountain roads that would be involved. The plate was loaded, together with the required counterweight and other accessories, onto two trucks that undertook the trying journey together with the crane – and it was a journey that truly came with unique challenges for the Fanger team. The route was not only peppered with tight curve radii, but also with tunnels that demanded absolute precision. “Sometimes we only had a few centimeters between the crane and the tunnel walls, meaning that our operator was threading the machine through the eye of the needle, so to speak” Josef Waser reports. And even though the team at Fanger is used to navigating this type of difficult route on the way to work sites in the Alps, they decided to use a signalperson to make sure everything went smoothly this time around.

Lifts with a radius of 27.5 meters

This enabled the crane and trucks to reach the concrete dam safely and on time, after which the team quickly set up the AC 160-5 despite the extremely tight space conditions – a mere six meters between the guardrails, to be precise. And in theory only: “We couldn’t extend the outriggers all the way to the edge of the dam due to safety reasons, so we were limited to an actual width of 5.4 meters after consulting with the responsible engineer,” Josef Waser reports. However, these conditions allowed the Demag AC 160-5 to truly shine with the IC 1 Plus control system and a small outrigger spread of 5.3 meters, proving that choosing it for the job had been the best possible decision: Lowering the load 130 meters down was no problem thanks to the powerful hoisting gear with a direct line pull of up to 9.9 tonnes, and the maximum wire rope length of 330 meters meant that the crane had more than adequate reserves for the job.

In order to be able to lower the suction excavator components, a pontoon, pipes, and other material – some of which weighed up to 7.8 tonnes – 130 meters down onto the reservoir, the crane was equipped with a 32.9-meter main boom and 46 tonnes of counterweight. “Due to the dam’s convex contour, we had to work with a radius of up to 27.5 meters. However, that wasn’t a problem whatsoever for our Demag AC 160-5,” reports Josef Waser, who is happy with the Demag crane’s performance and with the excellent service provided by the Demag team, with whom he has a good longstanding relationship: “It’s always good to know that we can count on good and fast service in any situation,” he highlights. Like with the vast majority of cases, however, everything went smoothly with the job, so that the crane operator was able to complete all the lifts by himself in a single day.

Zweibrücken, Germany – July 1st, 2021