Limitations Of Fall Arrest And Travel Restraint

Harnesses are only appropriate for certain conditions, such as maintenance after the roof is completed or re-roofing work, and they are not satisfactory when snagging hazards are present.

The use of fall arrest harnesses or travel restraint systems is not the preferred alternative for people working on roofs, as these methods have limitations including the following:

• Individual fall arrest anchors should have a capacity of at least 15 kN and roofs are generally not designed for such loadings; other anchorage points should withstand a load of 6 kN without failure.
• The location of fall arrest anchorage points on roofs cannot be located directly above head height.
• Fall arrest systems require a minimum of 5.5 m vertical clearance below the working surface to ensure the user does not hit the ground or another obstruction before the fall being arrested. This distance is required to be greater if static lines are used or ropes are slack.
• In contrast to guardrail or scaffolding, fall arrest and travel restraint systems require a high level of training and supervision to ensure their safe use.
• Ropes and lanyards can become tangled and snag on obstructions on the roof, particularly when a number of workers are located on the roof.
• It can be difficult to have an effective rescue procedure, to ensure users are rescued before injury occurs, without putting other people at risk.
• Persons suspended in harnesses after falling can lose consciousness or suffer modified cardiac rhythm if not rescued promptly and the rescue procedure should ensure persons can be rescued in less than 5 minutes.

Fall arrest systems must not be used unless specific training has been completed, that more than two people are located on site and any rescue procedure must not put other persons at risk.

The solo operation using fall arrest equipment is hazardous because there will be nobody to rescue a worker who could be unconscious and heavy. In some situations, at least two people may be required to safely rescue a person who has had a fall in a harness.

Systems that prevent a fall from occurring should be used in preference to fall arrest systems. Travel restraint systems are a higher order control in comparison to fall arrest systems because they prevent a fall actually occurring. However, travel restraint systems can be very difficult to set up and often impractical to use, particularly where corners of a roof require accessing or the roof has a number of penetrations.

Persons using travel restraint systems require a high degree of training, as do persons using fall arrest systems, but the training for these systems differs.

When used in isolation, fall arrest and travel restraint systems are nearly always unsuitable control measures for a complete roof installation, and it is extremely difficult to set up a fall arrest system so that the user will not hit an obstruction before the fall being arrested.

Fall arrest and travel restraint systems are generally only suitable for minor work such as:

• roof inspection (not on fragile roofs);
• installation of skylights and ventilation fixtures;
• installation and removal of perimeter guardrail systems;
• fitting ridge capping on metal roofs;
• replacement of some isolated parts of the roof;
• installations and removal of television aerials and other similar communication equipment; and
• painting and cleaning;