Liebherr Cranes Involved in Replacing Germany's Second Longest Road Bridge

Wed July 31, 2024
Liebherr

The replacement of the Rader High Bridge in Schleswig-Holstein is one of the largest bridge modernization projects currently under way in Germany.

The bridge, built back in 1972, spans the Kiel Canal and is part of the A7 motorway. Measuring approximately 4,920 ft. in length, it is Germany's second-longest steel road bridge and plays an important role in the flow of traffic to and from Denmark and the Scandinavian peninsula.

The bridge is approaching the end of its useful life as a result of high volumes of traffic, meaning that a rebuild and simultaneous widening of lanes has become necessary.

Photo courtesy of Liebherr

A Liebherr LR 1250 crawler crane, manufactured in Nenzing (Austria) made the assembly possible.

Cranes in Operation in Water, On Land

Strong support for this major construction project is being provided by 18 Liebherr cranes from the rental fleet of Friedrich Niemann GmbH & Co. KG, based in Kronshagen near Kiel. Five fast-erecting cranes, two 65 K.1s and three 81 K.1s, are on site to assist with the foundations. The new bridge piers are being built with the help of six 125 EC-B and seven 150 EC-B flat-top cranes.

Conditions on site are responsible for some spectacular crane assemblies. The first crane to arrive on the construction site, a 125 EC-B, was assembled at the end of 2023. Assembly took place in the waters of Lake Borgstedt, where the crane stood on the first pier's pile cap secured by foundation anchors. This involved working with a Liebherr crawler crane from Nenzing (Austria). The 275.5 ton LR 1250 crawler crane required for the assembly was positioned on a floating platform between the crane site and the ferry used for transporting parts. The flat-top crane reached a hook height of 144 ft.

Three 125 EC-B cranes also were assembled using the 275.5 ton crawler crane, from its floating platform on the water. The cranes were initially assembled at a height of 98.4 ft. and then climbed to their final hook height of 164 ft. using hydraulic climbing equipment. This allowed them to work some 49 ft. above the height of the roadway.

A 150 EC-B 8 Litronic started off working on the bridge pier on land. But the progression of the site required the crane to be moved to a new location. At the end of June 2024 it was time: the flat-top crane was moved from the north side of the bridge to the next bridge column and reassembled in the water.

The disassembled crane was transported to its new location on a ferry and put back together again with the help of a 242 ton crawler crane on a floating platform. Once assembled, it climbed to a hook height of around 164 ft. and reached a jib length of 131 ft. The crane has the capacity to lift up to 8.8 tons.

Photo courtesy of Liebherr

Some of the K cranes on site slew under the bridge and are therefore set up with their towers retracted.

Liebherr Project Department, Rental Fleet Support Planning, Implementation

Precise planning was required in advance for the use of the cranes, and Liebherr's own project department for large and special projects (Tower Crane Solutions, TCS) provided valuable support. A major challenge lay in the cranes being assembled by the crawler crane on the floating platform.

As the permissible hook height of the crawler crane on the floating platform was restricted, the assembly height had to be kept as low as possible. However, a certain tower height was also necessary so that the cranes could be climbed. Various options and tower systems were therefore investigated in the run-up to the project in order to find the best solution.

The configuration of the tower combinations was another major issue prior to planning crane operations; it was essential to prevent the towers from colliding with the newly erected bridge piers and any potential tower deformations.

Consequently, the fast-erecting cranes are only partly utilizing their maximum hook height. The two 65 K.1 cranes are in use with their tower retracted as they slew under the bridge, and the three 81 K.1 cranes also are assigned to work under the bridge as well as at maximum height above it. The 13 flat-top cranes are assembled in a free-standing position on crosses and foundation anchors; some of them are set in concrete in the water. They are working with a hook height of between 160.7 and 223 ft.

The hydraulic climbing equipment has been provided by the Liebherr Tower Crane Center, the Liebherr partner for special crane hire, crane components and used machines direct from the manufacturer.

Weather conditions present an extra challenge during construction work. The Rader High Bridge is closed to empty lorries and cars with trailers from wind force 9 onwards (storms with wind speeds of 46 to 55 mph). If the wind picks up further, it can be closed to all vehicles over 8.2 tons. In the event of a hurricane (wind force 12), the bridge is closed completely. The wind conditions therefore had to be taken into account in the cranes' static calculations.

Photo courtesy of Liebherr

Onwards to the next bridge pier: The cranes move as the site progresses and are assembled in situ, as here in the waters of Lake Borgstedt.

New Build in Two Stages

The Rader High Bridge is located east of the town of Rensburg, approximately 18.6 mi. from Kiel and around 40 mi. from Flensburg. Traffic currently flows across the Kiel Canal, Rader Island and Borgstedter Enge (part of Borgstedt Lake) on four lanes and two hard shoulders. The bridge's piers stand both on land and in the water. Three piers are being erected in the water and require a foundation of 131 ft.-deep bored piles.

The new build is happening in two stages with traffic flowing along the existing bridge as well as the Kiel Canal, the world's busiest man-made waterway. The eastern half of the bridge is being built first, next to the existing bridge, and is expected to be opened to traffic in 2026. Following this, the original bridge will close and be demolished, with the western bridge section being built in its place. The new structure is being widened to six lanes and should be finished in 2031.

The bridge piers for the eastern replacement structure are being erected first. Steel parts for the substructure arrive as 13 ft. long components and are welded together on land to create elements up to 262 ft. in length. These are then pushed along towards the next pier using the incremental launching method, with one increment being one bridge segment. To do this, the piers have to be erected well in advance of the launching process.

Work has started north of the bridge and is progressing southwards towards Lake Borgstedt and across Rader Island in the direction of the Kiel Canal. There also is work under way to the south of the bridge, on the banks of the canal. The construction project is being carried out by a consortium headed by the Swiss construction company Implenia AG together with two Saxony-based companies Plauen Stahl Technologie GmbH and ZSB Zwickauer Sonderstahlbau GmbH.

Photo courtesy of Liebherr

A crawler crane on a floating platform is used for assembly. The disassembled crane is transported to its new location by ferry.

Segment Reaches First Pier

On June 28, the first bridge segment reached the first pier. This particular segment is 183 ft. long, 46 ft. wide and 19.7 ft. high. Hydraulic presses moved the segment, which weighs several tons, at a speed of 29.5 to 32.8 ft. per hour southwards towards the first pier. The replacement structure will consist of a total of 14 sections, with one advancement planned for every six to seven weeks.

Photo courtesy of Liebherr

The replacement structure for the eastern half of the bridge is being built next to the existing bridge and is scheduled for completion in 2026.