Client : Clough Engineering
Location : Hegigio Gorge, Papua New Guniea
Year : 2005

In early 2005, Clough Engineering engaged Madsen Giersing to assist in the construction of a 470m span pipeline suspension bridge for Oil Search Limited. This bridge is located across the 500m deep Hegigio Gorge in the PNG Southern Highlands. Due to the complexity of the bridge, the remote location and the limited access around the abutments, innovative and unique design solutions were required to allow for the construction of the bridge.

The bridge comprises of three catenary cables, two horizontal and one vertical cable, which are joined together by a series of wire stays and cross beams. Two parallel runway beams connect the series of cross beams together, which allows access along the bridge via a trolley. The main cable is connected to a 33m high A-frame tower at the southern abutment and a 4m high tower at the northern abutment.

Madsen Giersing designed various structures to provide access during the construction. These included two temporary platforms bolted to the top of the south tower and two 12 storey 9m x 3m access towers. The access towers were also designed to allow the south tower A-frame to be raised using a specifically designed reeved system.

For the launching of the bridge, the horizontal cables, cross and runway beams, a restraint system was developed to allow the bridge to be launched in a safe and controlled manner. Several structures were designed to assist in forming, positioning and launching the horizontal cables, which consisted of 70 strands. These structures included a guide tower and cable reel and deflector towers.

For the installation of the two oil pipelines Madsen Giersing designed two trolleys. One to pull the pipelines across the bridge and the other to allow personnel access along the bridge in order to install the pipe clamps at the cross beams.

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