Tensioned lines

Horizontal lifelines

The main consideration when setting up a horizontal lifeline is the effect of angle loading on the system. The load on the lifeline and the anchors may be up to three times the load imposed on it.

Drag the sliders to see how span and sag combine into anchor tension — small sag means big force.

• ✓Solid anchor points should be selected at each side of the lifeline.
• ✓Intermediate anchors placed a maximum of 5 m apart.
• ✓The lifeline should run freely through the intermediate anchors (not knotted).
• ✓The rope should be hand tensioned through the descender.
• ✓The maximum allowable incline is 15° — anything above 15° should be treated as a vertical lifeline.
• ✓The lifeline should be rigged as high as possible in relation to the user to minimise potential falls.

Horizontal tensioned traverse lines

A horizontal tensioned traverse line will normally comprise two separate ropes running side by side in a horizontal plane, each rope separately anchored at both ends.

The operative or casualty should have two attachments to the ropes and maintain them at all times during the traverse. This can be achieved by attaching a short cow's tail to both ropes and then attaching a long cow's tail into both ropes.

Other equipment may assist movement along the traverse:

• A back-up device placed on one rope, trailing behind the operative to help control the descent down the first half of the traverse.
• A handled ascender to assist during the second, upward half.

Your instructor will show you these techniques and illustrate their limitations and potential dangers.

Operatives should be aware that unnecessary dynamic movement whilst traversing will place additional peak loads on the anchor point and associated connectors — possibly exceeding their designed Working Load Limit (WLL) or Safe Working Load (SWL).

Work restraint capability

These systems may also be used to offer a Work Restraint capability. Ensure the system does in fact prevent an operative from entering a falling hazard zone. Where such a system is in place, ensure all operatives are familiar with the maximum length of cow's tail / lanyard to be used on the system. It is acceptable to utilise a single rope in these situations.

Diagonal tensioned traverse lines

Diagonal tensioned traverse lines redirect the path of a descent or ascent from the vertical to a diagonal plane. They are used in addition to the operative's working and safety ropes, or the double-rope systems used for hauling and lowering.

• Similar in construction to horizontal lines — two separate ropes side by side, each separately attached to independent anchors at both ends.
• One end of the traverse ropes can be attached via suitable descender devices to enable the system to be tensioned or slackened.
• If tensioned, the angles created when loaded should be considered (deflection will be small and a high load will be exerted on the anchors).

Use as work positioning

The operative should descend or ascend their ropes in the normal way, whilst having two extra attachments to both traverse ropes. Rope can be taken in and out through the rope adjustment devices at any point during the ascent or descent — enabling the operative's position to be altered in both vertical and horizontal planes.

Use for rescue

The same system of double security should be employed — the casualty should be lowered on two independent systems whilst maintaining two attachments to the tensioned traverse lines.