4.1 Fall distance and fall geometry

The position of the anchorage affects both how far the user may fall and the direction in which the fall occurs.

The farther the user can fall before the system begins to arrest the fall, the greater the free-fall distance and the total distance required to stop the fall.

Where the system and task allow, the anchorage should therefore be positioned to minimise the free-fall distance.

Anchorage above, level with or below the user

An anchorage positioned high above the user will normally reduce the possible free-fall distance.

An anchorage positioned level with or below the user may allow a greater free-fall distance before the system begins to arrest the fall.

This affects, among other things:

• the total fall distance,
• the load on the system,
• the required clearance,
• the risk of striking the structure,
• the risk of a swing fall.

It is therefore not enough simply to ask whether the anchorage is strong enough.

You must also consider where it is positioned in relation to the user and the direction of the possible fall.

Fall factor as a simplified model

Fall factor is sometimes used as an educational model to describe the relationship between the possible fall distance and the length of the part of the system available to absorb the fall.

It can help illustrate why a low anchorage may create a less favourable fall.

However, fall factor alone does not tell you the actual fall distance or the forces that will occur.

The real situation is also affected by factors such as:

• product design,
• anchorage position,
• system length,
• energy absorption,
• elongation,
• user movement,
• workplace geometry.

Always use the manufacturer's instructions for the actual product when assessing the limitations of the system.

Remember

Anchorage position affects how far and in which direction you may fall. Minimise the free-fall distance.