Overpass Bridge, Wanneroo, Perth
The Ancon Unilift Lifting System, with its Cone Anchors and unique Locking Klaw Lifting Clutches, was used to provide secure lifting points during the transportation, rotation and final installation of multiple complex precast concrete piers supporting the new Joondalup Drive overpass bridge in Wanneroo, Perth, Western Australia.
With traffic levels surging due to ongoing development in Perth’s north-west suburbs, the interchange of Wanneroo Road and Joondalup Drive was becoming a pinch point, with growing congestion and gridlock predicted by the end of the decade. To improve safety and journey times, the $50 million development creates a new 4-lane overpass for Joondalup Drive with a new roundabout below it to ease congestion on the existing Wanneroo Road.
The challenge for our engineering team and precast contractor, Permacast, was to transport and install the enormous 36.8 tonne precast concrete piers in record time, with minimal disruption to the already very busy signalized intersection in WA.
Being cast horizontally in Permacast’s precast yard, the giant piers needed to be rotated and transported to site to be ready for installation. Besides the weight of the units, the progress of work on site introduced additional challenges as the space was restricted.
An additional requirement from the client was to maintain a clean, smooth finish to the unique crosshead piers’ surface, which meant no lifting points could be located on the exposed areas of concrete. This effectively limited the anchor location options to the upper and lower heavily reinforced faces and restricted the number of fixing points available to each face.
After going through multiple options, it was decided that rotating the giant precast units from their horizontal position to the vertical position should take place at the yard. The rotation was done in mid-air to prevent any damage to the piers when contacting the ground. Whilst this made installation on site easier, as the piers could simply be lowered into their final positions, it resulted in additional shear forces for the anchors.
Leviat was involved in this project from its early stages and supported the bridge designer, precaster and the construction team throughout the design process. The piers went through multiple revisions, which altered the weight and shape of the units, ultimately influencing the lifting design. Our technical team responded to the initial request within just 6 days, with a comprehensive lifting solution based on cast-in Ancon Unilift Cone Anchors with a Working Load Limit of 20 tonnes and a length of 340mm. The lifting anchors were used in conjunction with the unique 20-ton rated Ancon Unilift Locking Klaw.
The initial proposal included four face-mounted cast-in anchors for demoulding plus four additional anchors to the external surface to assist with the rotation. With the rejection of surface mounted anchors, our technical team developed an alternative configuration for the face-mounted anchors by using the cone anchors in the top and bottom of the pier for all lifting procedures including demoulding and rotation. This overcame the problem with anchor points on the external surfaces and avoided the need for extra face-mounted castings, which would have been difficult due to the limited space and heavy existing reinforcement. Our team could prove that the anchors, in combination with the Locking Klaws, could safely transfer the shear loads that were introduced.
To overcome the challenge of mid-air rotation, the technical team designed a special rigging system which provided the rotational movement needed safely and without the need for additional anchors.
The project proved a great success, with the units being manufactured, demoulded, rotated, delivered, and safely installed on the Wanneroo site without issue. Detailed lifting diagrams were produced to ensure that all lifting operations could be carried out quickly and safely, with minimum disruption to traffic flow at the junction.
The project demonstrates our experience and knowledge in lifting heavy concrete castings and its ability to find new and innovative solutions. We quickly responded to changes in specifications and site conditions, helping to make this a successful project. It coincides with the company’s recent rise to Industry Partner Membership of the National Precast Concrete Association Australia (NPCAA), underlining its increasingly important role within Australia’s precast industry.
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