Kaitoke Flume Bridge
Under construction by Brian Perry Civil, this 52m long Network Arch Bridge will carry a new seismic resilient Kurimoto pipe over Te Awa Kairangi (Hutt River) in the Kaitoke Regional Park. The pipe bridge conveys water from the Hutt River Kaitoke intake to the Te Marua storage lakes. The existing flume bridge will be replaced by the new, more resilient bridge to ensure the safe supply of drinking water for the Wellington region.
A lot of preparation work was required before the new bridge could be installed in place. 900m3 of rock and vegetation was cleared from the northern slope and 400m3 of rock and vegetation were cleared from the southern slope of the valley to prepare for the installation of horizontal anchors to the rock face. This challenging work was done by abseilers supported with a small crawler crane. Over 200 horizontal rock anchors were installed, each drilled 6m into the rock face for earthquake stability and resilience.
Twenty vertical rock anchors were installed to widen the access road for larger machinery to access the site to both construct the new bridge and demolish the old bridge.
Each bridge abutment is made of six reinforced concrete piles embedded in the rock, with a capping beam tying them together. The bridge (superstructure) lies on bearings and a concrete slab, allowing sliding motion in severe seismic events. The web forge bridge walkway will have railings at two levels and a sliding joint at the abutments to connect to the northern and southern walkway ramps.
BPC installed a Favco M860D luffing tower crane for the works, which is the largest tower crane owned in New Zealand. With a 22m tower and 64m luffing boom it has the capacity to lift 11T at 62.5m radius or 32t at 32m radius. Its work at Kaitoke includes lifting a 10t piling rig at 60m radius to the other side of the river on temporary stagging to perform the works, installing the 30t bridge steelwork, and removing the old concrete bridge sections during demolition.
Awards
- 2023 Crane Association of New Zealand People's Choice Award - Tower Crane Install
