JUNEAU, AK — The construction of the Juneau Creek Bridge, with a span of over 950 feet, is the centrerpiece of one of the largest infrastructure projects in Alaska. The bridge will significantly increase the traffic capacity on the Sterling Highway between Anchorage and the Kenai Peninsula and also improve safety. Traylor Bros, Inc. relies on two Liebherr LR 1300.1 SX Crawler Cranes that are playing a crucial lifting role during the assembly of the bridge sections.
The steel girders of the bridge are assembled on one side of the canyon and then gradually pushed over the deep Juneau Creek Canyon to Cooper Landing with hydraulic presses using the bridge launch technique. Using this technology, the massive individual sections can be positioned precisely without the need for complex scaffolding across the chasm.
"The most challenging lift for us was the first girders of the bridge," said Travis Ludlow, Crane Driver of one of the LR 1300.1 SX at Traylor Bros, Inc. "They were very heavy, and I had to rely on a lot of ground people because wind was coming in. We could see up to 40 mph winds. So I am very happy that we therefore have two Liebherr crawler cranes — one on each side of the project."
He is particularly pleased with the cranes’ Gradient Travel Aid for safely negotiating slopes, which is challenging due to the topographical conditions of the project. The crane’s control system automatically calculates the center of gravity and warns the operator before the crane leaves the safe area. While traveling, the operator receives real-time information about the permissible and actual gradient, and the crane’s overall center of gravity at all times. If necessary, the main boom angle can be altered so that the machine remains in the safe area.
Only solid steel girders are being used for the Juneau Creek Bridge. These allow for wide spans and a high load-bearing capacity with minimum material weight. The girders must be aligned with millimeter precision to achieve the necessary stability for the bridge. Traylor Bros, Inc. is carrying out this job with the two crawler cranes, so that the bridge can grow safely and efficiently across the canyon.
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"There were several factors that went into the decision to choose the LR 1300.1 SX," said Tyler Becker, Senior Field Engineer at Traylor Bros, Inc. "The reliability of the crawler cranes is incredibly important for our project site. We have a small window before the weather kicks us out. Any malfunctions would cause massive schedule delays. The LR 1300.1 SX works when we need it. It has the versatility and the capacity to handle all the lifts we need to do."
The bridge has to withstand the extreme weather conditions in Alaska: strong snowfall, biting winds, and great temperature swings. The seismic activities in the region were also considered in the technical calculations, in order to provide sufficient safety in the event of earthquakes. The remote location and the surrounding natural habitats required careful planning of the project so that the ecological impact could be minimized.
Steep slopes and limited access roads make the positioning of large bridge components extremely difficult. Traylor Bros, Inc. planned the whole deployment of the two crawler cranes in advance and also during the work using Liebherr’s 3D software Crane Planner 2.0. By simulating the lifts, the company is supported in taking all scenarios into account and also finding solutions for them in advance so that the bridge project can be completed safely, efficiently, and on time.
