Fall Arrest Planning: Clearance, Anchors, and Rescue

A harness and a lanyard do not protect anyone on their own. A fall arrest system only works if someone answered three questions before the worker tied off. Will the worker hit anything before the system stops them? Will the anchor hold? How will they get down afterward? This is the planning side of fall arrest, for lead workers, competent persons and anyone who sets up tie-off points. The figures here are rules of thumb and legal minimums. The label on your equipment and your qualified person have the final word.

What You Will Be Able to Do

• Work out free fall from where the anchor sits.
• Add up total fall distance for a lanyard and for a self-retracting lifeline.
• Explain why the same fall can be quoted as 13.5 feet or 18.5 feet.
• Calculate the extra drop in a swing fall.
• Match anchors to arrest, positioning and restraint.
• Write the main parts of a rescue plan.

Start With Free Fall

Free fall is how far you drop before the system starts to slow you down. OSHA's limit is 6 feet. Free fall depends on the length of the connector and on where the anchor sits compared to your dorsal D-ring, which is about 5 feet above your feet.

Use this formula for a fixed-length lanyard:

Free fall = lanyard length + distance the D-ring sits above the anchor

If the anchor is above the D-ring, subtract that distance instead.

Worked example: A worker ties a 6-foot lanyard to an eyebolt 1 foot above the deck.

1. The D-ring is 5 feet above the deck.
2. The D-ring sits 4 feet above the anchor.
3. Free fall = 6 + 4 = 10 feet.
4. That breaks the 6-foot limit. Move the anchor up, or use equipment rated for a low anchor.

Add Up the Total Fall

Once you know the free fall, add the rest:

1. Free fall. From the step above.
2. Deceleration distance. How far the shock absorber or brake extends while stopping you. OSHA's limit is 3.5 feet.
3. Harness stretch and D-ring shift. The harness stretches and the D-ring slides up your back. About 1 foot is common.
4. Worker height. Your feet hang about 5 feet below the D-ring, so it matters where you start measuring.
5. Safety margin. Extra room so you do not touch whatever is below. Three feet is common. Some makers state 2 feet.

Lanyard Example

With a 6-foot shock-absorbing lanyard anchored at D-ring height, measured below the walking surface:

SRL Example

An SRL anchored overhead usually locks within about 2 feet and stops you in a further 2 feet or so.

An SRL anchored low or at foot level behaves very differently. It may need a leading-edge model and much more clearance, so read the label.

Why You May See 18.5 Feet

Some charts quote about 18.5 feet for the same lanyard. That is not a conflict. It is the same fall, measured from the anchor rather than from your feet.

1. Lanyard: 6 feet.
2. Deceleration: 3.5 feet.
3. D-ring to feet, plus stretch: 6 feet.
4. Safety margin: 3 feet.
5. Total below the anchor: 18.5 feet.

The anchor sits about 5 feet above the walking surface, so 18.5 - 5 = 13.5 feet below your feet. Before you use any chart, confirm the point it measures from.

Check the Whole Path

Measure to the first thing you would hit, and that may not be the ground. A beam, a machine, a stack of pallets, a lower roof or a scaffold all count.

Worked example: You work from a platform 15 feet above a floor, but a pipe rack sits 11 feet below the platform.

1. A 6-foot lanyard needs 13.5 feet.
2. The real clearance is 11 feet, so the lanyard is not safe, even though the floor is 15 feet down.
3. An SRL anchored overhead needs about 8 feet, so it fits.

Other things can increase the distance:

• Weight. Gear is rated for a maximum weight including clothes and tools. Many systems are rated up to 310 pounds. A heavier load stretches further, or may need a different rating.
• Horizontal lifelines. These sag when loaded, which can add several feet. A qualified person must design them, and that design gives the clearance.
• Rope stretch. Long vertical lifelines stretch more than short ones.

Swing Falls

If your anchor is off to the side, you do not fall straight down. You swing back toward a point under the anchor, like a pendulum. You can slam into a wall or column, and you also drop further than you might expect.

Worked example: An SRL is anchored 10 feet above the roof surface, and you are working 15 feet to the side of that point.

1. Line paid out: square root of (10 x 10 + 15 x 15) = square root of 325 = about 18 feet.
2. When you swing under the anchor, the line hangs straight down, 18 feet below it.
3. That point is 18 - 10 = 8 feet below the roof surface, before you count deceleration or body length.

Ways to control swing falls:

• Keep your anchor as nearly overhead as you can.
• Move the anchor as you move the work.
• Use a horizontal lifeline or a trolley, so the tie-off point travels with you.
• Follow the maker's limit on how far you may work to the side.

Anchors

Before you tie off, ask what the anchor is, what it is rated for and who approved it.

The last row is guidance rather than a written rule. OSHA's main construction fall protection rules have no restraint section, so its letters suggest that minimum and tell employers to consider the forces from walking, slipping or sliding. For steel erection, restraint anchors must meet the fall arrest rule. In practice, many employers simply use 5,000-pound anchors for everything, which removes the doubt.

A good anchor:

• Is part of a sound structure, or an engineered anchor installed to the maker's instructions.
• Is separate from anything holding up a platform or suspended worker.
• Sits at or above D-ring height, where possible.
• Lines up over the work, to limit swing.
• Has no sharp edge that the line could run across.

Poor choices include conduit, sprinkler pipe, handrails, roof vents, guardrails, ladder rungs and light fixtures. A beam strap around a sound steel beam can be a good anchor if it is rated for the job and the beam is known to be strong enough.

Other system rules worth knowing:

• Lifelines and lanyards generally need a 5,000-pound breaking strength. SRLs that limit free fall to 2 feet or less need 3,000 pounds.
• In general, each worker uses a separate vertical lifeline.
• Horizontal lifelines are always designed under a qualified person.
• The harness attachment point goes in the center of the back near shoulder level, or above the head.

Rescue Planning

OSHA requires employers to provide for prompt rescue, or to make sure workers can rescue themselves. The rule does not give a number of minutes. Many employers plan to reach a fallen worker within about 6 minutes, and an industry standard points in the same direction. The point is the same: minutes matter.

A person hanging still can lose consciousness as blood pools in the legs. Workers who are hurt, cold or knocked out are at the greatest risk. OSHA warns that this can cause serious or fatal injury if the worker is not rescued promptly.

What the Plan Needs

Write a plan for each location and task, not one plan for the whole company.

1. How you will know. Who sees the fall, and how they call for help when working alone is not allowed.
2. Who rescues. Named and trained people, on site during the work.
3. How. The specific method and gear for this location.
4. Access. How rescuers reach the worker, such as by lift, ladder or a line from above.
5. Emergency medical care. How to call for it, what address to give, and where an ambulance can reach.
6. Practice. A drill with the real equipment, so that you find the problems early.

Calling 911 alone is seldom enough, because outside responders may not arrive quickly or have the right gear for your site. Find out what your local responders can really do.

Rescue Options

While you wait, a conscious worker should keep moving their legs. Relief straps let the worker stand in a loop and take pressure off the leg straps.

After the Rescue

Older training said not to lay a rescued worker flat. Later reviews, including work published by the UK Health and Safety Executive, found no evidence for that advice. Give normal first aid. If the worker is unconscious, keep the airway open and start CPR if needed. Call emergency services for anyone who has been suspended, even if they feel fine, and tell responders how long the person hung.

Then take the gear out of service, and review the incident before anyone goes back up.

Common Mistakes

Check Your Understanding

1. You anchor at D-ring height with a 6-foot lanyard. What is the free fall, and is it allowed?

About 6 feet. That is right at OSHA's limit, so it is allowed if there is enough clearance below.

2. One sheet says 13.5 feet of clearance, and another says 18.5 feet, for the same lanyard. Who is right?

Both can be. One measures below the walking surface, and the other below the anchor. Check the reference point.

3. You are 20 feet to the side of an overhead anchor that sits 15 feet above you. How much extra drop could a swing add?

The line is 25 feet long. Swinging under the anchor puts you 25 - 15 = 10 feet below your starting level. Move the anchor.

4. A general contractor says, "If somebody falls, we'll call the fire department." What would you ask?

How long they would take, whether they can reach a hanging worker at this site, and who rescues the worker before they arrive. That answer alone is not a plan for prompt rescue.

5. A coworker reaches a rescued worker who is awake and wants to sit him upright for 30 minutes before laying him down. What should you do?

Use normal first aid and let him lie down if he needs to, while monitoring him. Call emergency services.

Key Takeaways

• Free fall depends on connector length and anchor position, and OSHA caps it at 6 feet.
• A 6-foot lanyard needs about 13.5 feet below the walking surface, and an SRL overhead needs about 8 feet.
• Figures measured from the anchor are bigger than those measured from the surface.
• Measure to the first object you would hit, and watch for swing falls.
• Fall arrest anchors need 5,000 pounds per worker or a 2:1 design under a qualified person.
• Restraint and positioning have their own numbers, and they differ between construction and general industry.
• Write a rescue plan for each task, and practice it.