Hegigio Gorge Pipe Bridge
Hegigio Gorge, Papua New Guinea
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
Due to the remote location and limited access around the abutments, innovative and unique design solutions were required to allow for the construction of the bridge.
A restraint system was developed to enable the bridge, horizontal cables, cross and runway beams to be launched in a safe and controlled manner. Several structures were designed to assist in forming, positioning and launching the horizontal cables. These structures included a guide tower, cable reel and deflector towers.
For the installation of the two oil pipelines, MG 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
The bridge comprises three catenary cables, two horizontal and one vertical cable 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 33 m high A-frame tower at the southern abutment and a 4 m high tower at the northern abutment.
MG designed various structures to provide access during construction. These included two temporary platforms bolted to the top of the south tower and two twelve story 9m x 3m access towers. These access towers were also designed to allow the south tower A-frame to be raised using a winch reeved to the top of the tower.