Specularite Gully Bridge Build. Winner of the 2022 CCNZ category 1 national award

The Lake Dunstan trail is part of the network of cycle trails throughout Central Otago. Running along the western shores of the lake, it links Cromwell to Clyde. A significant challenge for cyclists on the trail is Specularite gully, a rocky crevasse named after the remarkable schist rock with specularite inclusions.

Abseil Access won the tender to design and build this unique structure alongside the other trail building teams. Due to limited access to the site, all materials and tools had to be flown across lake Dunstan by helicopter, including the heli-portable pneumatic drill rig, compressor and grout plant.

The Main cable anchors were drilled 9m into the hard schist rock to provide a working load capacity of over 300kN. The 28mm IWRC main cables support 15 tons of deck, a 240kN live load, or a snow load of 25tons.

The 11m high timber towers were darkly stained to blend into the environment, and the steel components are Corten weathering steel. The wind cables are catenary and capable of stabilising the deck in winds up to 230km/hr.

The total turnaround time from concept to handover was four months.

Works for this project included:

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