Engineered Tensioned Cable Systems
Engineered access where conventional methods aren't possible.
A tensioned cable system, sometimes called a zip line or tight line, is a wire rope tensioned between two engineered anchorages, with a trolley that runs along it carrying suspended loads. Travel along the line is controlled by a hydraulic winch, and the line is routed to clear obstructions such as power lines and operating plant.
Moving Loads Where There Is No Access Route
On rockfall and slope stabilisation works, the systems deliver heavy construction materials directly to work areas on steep ground. Where accumulated rockfall or debris has to be cleared from a location with no vehicle access or safe manual handling route, they carry it out in bagged loads. They can also move plant into areas that would not otherwise be accessible, allowing higher production drilling plant to be used in place of lighter equipment. The same approach suits mine sites where highwalls, pit walls or benches have been cut off from conventional access.
Designed and Engineered In-House
Design starts from the loading and receiving locations and the ground profile between them, the ground conditions at each terminal, overhead constraints such as power lines and live plant, and how long the system will remain on site.
For Fremont Canyon, the design load combined a full bulk bag of wet rock with the trolley, lifting gear and hoist. A dynamic factor of 1.3 was then applied, giving a design load of 1.95 t. Rope tension was checked with the load at midspan and 1 m from each anchor. This gave a maximum tension of 57.5 kN on a 22 mm Geobrugg GEOBINEX wire rope, and a factor of safety of 7.0 against its minimum breaking strength. The resulting anchor reactions formed the basis of the anchor design at each terminal.
Operational Advantages
Repeatable load cycles between fixed loading and receiving points, suited to sustained material movement rather than one-off lifts
Loads travel unaccompanied, so crews are not carrying or escorting material across the slope
Works run in parallel, so material movement does not hold up the main programme
Fremont Canyon Power Plant
At Fremont Canyon Power Plant in Wyoming, approximately 535 m³ (700 cubic yards) of accumulated rockfall had to be removed from behind the plant before a replacement lower barrier could be built. There was no vehicle access, the newly installed upper barriers occupied the only access corridor, and power lines made helicopter support almost impossible. Geovert installed a 52.5 m tensioned cable system to carry bagged debris over the power lines and operating plant to the front of the facility. A spider excavator positioned the material, rope access crews loaded each bag, and removal ran in parallel with barrier installation.
