Madsen Giersing (MG) was engaged by Clough to assist in the construction of a 470 m span pipeline suspension bridge across the 500 m deep Hegigio Gorge in the PNG Southern Highlands.
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 brige comprises three catenary cables; two horizontal and one vertical joined together by a series of wire stays and cross beams. Two parallel runway beams connect the series of cross beams together, which allow 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 northen abutment.
Madsen Giersing design various structures to provide access during construction including 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 design to allow the south tower A-frame to be raised using a reeved system specifically designed for this purpose.
In order to launch the bridge, 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, each comprised of 70 strands. These structures included a guide tower, cable reel and deflector towers.
Madsen Giersing designed two trolleys for installation of the oil pipelines; one to pull the pipelines across the bridge and the other to allow personnel access along the bridge in order to install pipe clamps at the cross beams.
Hegigio Gorge, Papua New Guinea
Oil Search Limited