Swing Fall

What Does Swing Fall Mean?

A swing fall happens when a worker wearing a personal fall arrest system (PFAS) falls off an edge while working too far from the anchor point. This results in the worker moving in a back-and-forth motion while suspended in their harness.

Swing falls can be very dangerous, especially where there is a risk of the worker swinging into a nearby structure.

Swing falls are also known as pendulum swings or pendulum falls.

Safeopedia Explains Swing Fall

The Dangers of a Swing Fall

A swing fall might not sound like a serious major hazard – after all, it happens after a free fall has already been stopped. But they can cause serious injuries or become fatal.

These are three most significant risks when a worker enters a swing fall.

Collision with Objects and Structures

The greatest danger of a swing fall is the risk of colliding with structures, machinery, or other objects in the path of the swing. The horizontal velocity of a swing fall can exceed 20 miles per hour. Colliding with a solid surface at this speed can cause serious harm.

Construction sites also have unfinished structures, which can have sharp edges, protruding metal rods, girders, and other features that could aggravate the severity of injuries.

Lifeline Failure

During a swing fall, the lifeline can move back and forth along the edge. If the edge is unfinished, jagged, or sharp, this motion can cause the edge to saw through the lifeline. If the lifeline fails, it can result in a fatal fall.

Increased Fall Arrest Distance

When a worker wanders too far from their anchor point, their lifeline will pay out. If they fall, the lifeline will lock at a greater length than intended. This longer lifeline will result in a greater free fall distance, meaning the fall may not be arrested safely and the fallen worker could reach the ground.

What Causes a Swing Fall?

Working Too Far From the Anchor Point

Tying off to an overhead anchor point is ideal, but it still creates a limited safe zone for the user to work in. Wandering too far from the anchor point will increase the risk of a swing if a fall occurs.

Any location where the user’s lanyard or lifeline creates a 30 degree angle or greater (starting from the point directly below the anchorage) is outside that user’s safe zone. During a fall arrest, the worker will be pulled back toward the anchor point. If they are too far from that anchor point, this will create a pendulum effect, putting them at risk.

Tying Off at Foot Level

Swing falls can also happen when a worker cannot tie off overhead.

Tying off at foot level or waist level can be acceptable but is considered a last resort since it introduces additional risks. One of these is a longer free fall distance before the fall arrest system can engage and stop the fall.

In most cases, fall arrest systems should be designed to allow a maximum free fall distance of six feet. However, this isn’t always possible when tying off below the D-ring level on the harness. And the further the worker falls before the fall is arrested, the more sway there will be in the line. Given enough distance, that sway will turn into a swing.

Swing Falls and Fall Clearance Calculations

Fall clearance is the minimum distance required to safely arrest a fall from heights. Accurately calculating the fall clearance ensures that the worker will not come into contact with the ground or any obstructions below the work area during a fall.

If someone falls while working off-center from their anchor point, however, they may enter a swing fall. That possibility must be factored into the fall clearance calculation, as it significantly increases the distance needed to arrest the fall safely.

Free Fall Distance and Speed in a Swing Fall

The total free fall distance a worker must be able to clear before their PFAS slows and arrests the fall is determined by a number of different factors:

• Height of the anchor point
• Length of the lanyard or lifeline
• Free fall distance – The distance a worker will fall before the fall arrest system springs into action. It must be less than 6 feet and must prevent contact with a lower level.
• Deceleration distance – The length of the shock-absorbing lanyard when it is stretched to decelerate the fall. It must be no more than 3.5 feet.
• Dorsal D-ring height – The distance between the worker’s shoe sole and the D-ring on the back of their harness. The default is 5 feet, but must be adjusted for workers who are at least 6 feet tall.
• D-ring shift – Additional distance (assumed to be one foot) to accommodate the movement of the D-ring and harness when they are jerked upward by the fall arrest.
• Safety factor – An additional distance included to account for things that could go wrong (like an improperly fitted harness or a slight mistake in the fall clearance calculation). This is typically 2 feet, but can be 3 feet or more.

When a worker wanders beyond the 30-degree safe zone, this calculation is no longer accuate since the lanyard’s length will be much longer. Likewise, the further the worker moves away from the anchor point, the greater the free fall distance and speed will be.

To calculate the free fall distance and speed of a swing fall, follow these steps:

• A = The length of the line attached to the dorsal D-ring when it is directly below the anchor point
• B = The length of the line when the worker is at the furthest edge of the work area
• C = The difference between A and B, which represents the vertical free fall distance
• Swing speed (in feet per second) = C x 32 x 2 x 2

This represents the free fall distance multiplied by 32 feet per second per second – the effect of gravity on a falling object.

How to Prevent Swing Falls

Establish a Maximum Work Range

The closer the worker can stay to their anchor point, the less likely they are to experience a swing fall if they fall over an open edge.

A competent person should calculate the maximum work range from the anchor point. The employer should then train workers to understand the safe zone, how to work within it, and the risks associated with wandering outside of it.

Select a Suitable Anchor Point

The anchor point should be located above the worker’s head. Avoid creating a situation where anyone has to tie off at waist or foot level unless it is absolutely necessary.

The anchor point should be in a location that allows the worker to do their job without having to leave the safe zone.

Use Mobile Anchorage Where Needed

Mobile anchors move with the worker, expanding the size of the safe zone and allowing them to move across the worksite without extending their lifeline.

Keep the Lanyard or Lifeline Short

The longer the lifeline or lanyard, the greater the swing. Using a shorter line can restrict how far workers can travel from the anchor point and limits the pendulum effect if a fall does take place.

Use a Leading Edge SRL

A self-retracting lifeline (SRL) rated for leading edge applications is designed to withstand the sharp and unfinished edges that are characteristic of leading edge work.

While these types of SRLs won’t prevent a swing fall from happening, they can limit the resulting harm. Since the line is made of stronger materials, the sawing motion from the swing fall will not result in a snapped line – and a free fall to the lower level.