Puzzle solver: Demag® CC 3800-1 lattice boom crawler crane lifts bridge components at freeway work site

84-meter-long main boom set up without Superlift counterweight

Advertisement

Setting up heavy cranes with a large lifting capacity demands one thing above all when setting up the main boom: Space. A lot of it. This can quickly become a daunting challenge at tight work sites where every meter literally counts. When replacing the old viaduct on the A45 Freeway that spans the Lahn River near Dorlar, Bietigheim-Bissingen-based crane service provider Wiesbauer solved this problem with the Demag® CC 3800-1, which made it possible to set up the 84-meter-long main boom without a Superlift counterweight, thus saving space.

“This work site required us to lift loads of 96 to 148 tonnes at radiuses of 40 to 64 meters, so there was no option but to use a crawler crane in the 650-tonne class despite the constrained space conditions,” Wiesbauer project manager Marco Wilhelm succinctly explains. The company decided on the Demag CC 3800-1 lattice boom crawler crane, which was then assisted by an AC 160-5 all terrain crane from the same manufacturer. However, before the CC 3800-1 could be brought to the job site, its work area needed to be prepared first: “The Lahn flows right along the work site, so the ground wouldn’t have been able to bear the heavy load exerted by our machine. That’s why the work area was prepared with a concrete foundation for the crane,” Marco Wilhelm explains.

255-tonne counterweight

This made it possible to safely set up the crane with an LSL 1 configuration featuring an 84-meter main boom, 36-meter Superlift boom, 50-tonne central ballast, and 225-tonne counterweight, with the counterweight in particular being absolutely crucial. “The extremely heavy counterweight enabled us to set up the main boom without an additional Superlift counterweight. Moreover, this was what made it possible to use the enormous crawler crane to pick up the loads at such a tight work site, as leaving out the Superlift counterweight actually increased the crane’s usable working area significantly,” Marco Wilhelm says. In fact, the Superlift counterweight was not needed until later during the lift.

Between river and railroad

Once the preparation work was done, the Wiesbauer team was ready to carry out all the lifts with the Demag CC 3800-1. In order to build the two bridge sections, it was necessary to perform the work in two different steps at two different work areas: The steel components had to be lifted over the Lahn river in one step, and over a parallel rail line in the other. In each step of the project, one steel cross beam and four longitudinal steel girders had to be put into position. All these lifts followed the same pattern: Due to the space limitations, the Demag CC 3800-1 crane picked up the steel beams – which were up to 54 meters long and weighed 96 to 148 tonnes – from the SPMT units without a Superlift counterweight. The crane then slew to a pick-up point where it would be possible to attach the ready-to-go Superlift counterweight frame and its counterweight of 325 tonnes to the Demag CC 3800-1 so that the latter would be able to work in bigger radii and, lift the beams to a height of around 22 meters and then set them down at the intended bridge points. The radii ranged from 40 to 64 meters. And due to their length, the beams were rigged to 20 and 25-meter-long spreader beams that made it possible to achieve the required precision for the lifts.

A tricky schedule

One of the priorities during the project was to minimize its impact on rail traffic, which is why the Wiesbauer team had to perform most of the lifts at night within very tightly defined time windows during which rail traffic paused. Despite these tight time windows and space conditions, however, the team was able to successfully complete both steps in a mere five weeks – and all of it including setup, lifting, disassembly, and then moving the crane to the other work area, including the corresponding setup and disassembly after lifting the last steel beam. “What our people achieved was really something,” Marco Wilhelm says while praising his team’s impeccable professionalism. Both the team members’ experience and the Demag CC 3800-1 crane’s powerful performance characteristics were to thank for the fact that the team was able to stick to the schedule – as were the outstanding weather conditions that also worked out in the challenging project’s favor.