Solution Summary: Leading Edge Fall Protection System
Pre-punching holes in steel columns for horizontal lifelines and wire guardrails.
Description:
Leading Edge Fall Protection System incorporates a prevention through design (PtD) component that requires the specification of pre-punched holes in structural steel columns for cable guardrails and horizontal lifelines above shoulder level to prevent worker exposure to fall hazards when installing metal decking. This preplanning process specifies fabricators to punch holes at a specific height and then requires a qualified person to review the site-specific design of these columns before they are erected. Cables are then attached through the holes to construct the lifelines and form the guardrails once the decking is placed.
During the installment of metal decking, workers spread metal sheets over narrow structural beams to form the building's flooring, constantly creating a new working surface called the "leading edge." Because no viable solutions were available for decking operations, the rule on structural steel erection, Subpart R of OSHA's construction regulations, allows specially trained workers installing metal decking inside a controlled decking zone with fall hazards of less than 30 feet or two stories to work without fall protection. Workers not installing decking are not allowed inside this controlled zone. Thus, the Leading Edge Fall Protection System (see figure 1) is designed to control the unique fall hazards posed by leading edge work.
Figure 1. Leading Edge Protection System (Photo courtesy of CPWR)
This leading edge fall protection system, adopted by original CPWR material (see 'Availability'), can be implemented in the following steps:
Step 1
Before delivery, preplan and work with the fabricator to pre-punch holes in steel columns at three levels: 84, 42 and 21 inches above the decking levels. 84-inch holes are for horizontal lifelines. 42- and 21-inch holes are available for attaching guardrails at the perimeter or for the interior edge protection as needed.
Step 2
Before the fall protection system is installed, a Qualified Person should review the site-specific design. OSHA, 29 CFR 1926.32(l) defines "Qualified Person" as "one who, by possession of a recognized degree, certificate, or prefessional standing, or who by extensive knowledge, training and experience, has successfully demonstrated his ability to solve or resolve problems relating to the subject matter, the work, or the project." In special circumstances, a registered professional engeineer should evaluate or design the system.
Step 3
Choose one of three different methods to install the horizontal lifelines, depending on the individual site conditions.
Method 1: Once the pre-punched columns have been erected, install the lifelines from aerial lifts. In this instance, workers must be tied off to the aerial lift.
Method 2: Before the columns are erected into place, attach retractable lifelines to the columns to provide fall protection for the worker who is installing the leading edge fall protection system. A tag line is attached to the lifeline hook so that, after erection of the pre-punched column, the worker can pull out the line from the ground and attach it to his/her body harness. The worker can then climb the pre-punched column and perform the work of installing the lifelines with 100% fall protection.
Method 3: Before the beams are put into place, attach a Beam Post System, available from commercial suppliers, to the beam (see figure 2). This Beam Post method provides a pre-engineered horizontal lifeline system. The system is erected on the ground and is ready to use when the beam is lifted and secured in place. Safety net cables, where appropriate, can also be placed in the web of beams on the ground and lifted into place.
Figure 2. Pre-engineered horizontal lifeline system attached to an I-beam. (Photo courtesy of 3M)
Step 4
Attach the lifelines (cables) through the 84-inch high pre-punched holes parallel to the direction in which the leading edge is moving and a third cable perpendicular to the first two cables, with the two ends attached to these cables (see figure 3).
Figure 3. Cable configuration. (Photo courtesy of CPWR)
Step 5
Attach lanyards with shock absorbers to reduce the maximum arresting force and to minimize strain on the horizontal lifelines and on the worker (see figure 4). The lanyards can be connected to all three horizontal cables to provide fall protection for workers installing the decking. This arrangment prevents the tangling of lanyards that occurs with conventional waist-high systems. Retractable lifelines should not be used because they should only be attached to a fixed anchorage point. Horizontal lifelines are not a fixed anchorage point.
Figure 4. Body harness, lanyard and shock absorber for tying off to leading edge fall protection. (Photo courtesy of Super Anchor Safety)
Risks Addressed:
Workers risk falling off the unprotected sides of the work zone's leading edge and through floor openings in the deck. Falls from height typically result in severe injuries or death.
With conventional horizontal lifelines, the worker's personal fall protection lanyard is attached below shoulder level, creating a fall distance that could allow the worker to hit the deck below. Workers may also entangle their lanyards when connected to the same horizontal lifeline.
How Risks are Reduced:
Installing cable guardrails at the specific required height designated by the pre-punched holes on the steel column can eliminate the risk of a fall over an exposed open side. When constructed correctly, guardrails can prevent a worker from falling from elevated workplaces. Guardrails provide a physical barrier between the worker and the fall hazard.
Designating pre-punched holes 7 feet above the decking level, higher than the conventional horizontal lifeline height, allows a personal fall protection lanyard to be attached above shoulder level, decreasing the fall distance and the likelihood that a falling worker will strike the deck below.
Although conventional fall protection methods such as installing guardrails and safety nets are effective for many structural steel erection tasks, they are impractical for leading-edge decking work. Guardrails cannot be attached at the leading edge because the decking work zone is constantly moving forward as new decking is laid down. Safety nets, which must be placed under the work zone, are not practial for use with the constantly moving work surface. In addition, in most cases, the required 25 feet of clearance for safety nets is not available due to the metal deck on the floor below. The lack of clearance between the nets and the floor means that a worker could fall and strike the structure, equipment, or floor below.
Additional Considerations:
OSHA 1926.502(b) provides safety and health regulations for construction pertaining to guardrail systems.
Center of Gravity
The height of the guardrail (42") is designed to protect workers with their center of gravity below the top rail. A worker with a center of gravity above the top rail is in danger of falling over the guardrail if he comes in contact with the guardrail. A person's center of gravity is typically around their midsection. If a worker's center of gravity is above the top rail, that person should stay back at least 6 feet from the guardrail. An alternative is to extend the guardrail upwards. Guardrails can be extended to 45 inches high.
A recent innovation in railings, which is typically seen in atrium style hotels, places an addition to the top tail positioned outward and upward 10 to 12 inches and at a slope of 30 to 35 degrees from vertical.
Installing Guardrails
Installing guardrails can be a dangerous activity. While the worker or workers are installing the guardrail there is typically no fall protection for possible fall hazards until the guardrail installation is completed. It is best to pre-plan and engineer anchorage points or horizontal lifelines for the installation workers to tie off restraint systems or personal fall arrest systems for protection while the guardrails are installed.
Equipment Mixing and Mismatching
Employers and employees must both realize that components of a system may not be interchangeable. No component of a fall arrest system should be substituted or changed unless fully evaluated and tested by a competent person or the equipment manufacturer. When purchasing a fall protection system, it is best to purchase a complete system from a reputable manufacturer or authorized dealer.
Equipment Inspection and Storage
Fall protection equipment should be inspected frequently and before each use to ensure damage has not occurred. Hardware should be inspected for corrosion, burrs, sharp edges, chemical damage, too much wear, discoloration, deformation, and cracks. Software should be inspected for fraying, unsplicing, unlaying, kinking, knotting, roping, broken or pulled stitches, abrasion, chemical damage, or sections that are too old, too worn, or too dirty. Any equipment found with excessive damage should be marked "Do Not Use" and removed from service. Follow manufacturer's instruction on inspecting.
Fall protection equipment must be stored correctly and according to manufacturer's instructions. Store equipment away from heat, light, dampness, oil, chemicals or other damaging conditions.
Contributors:
Le, Jean Christophe, MPH - CPWR - The Center for Construction for Research and Training
Availability
Spider by Brand Safway
To obtain information, visit SpiderLine Temporary Horizontal Lifeline System
or contact 1-877-774-3370 spider@spiderstaging.com
Capital Safety (3M)
To obtain information, visit SecuraSpan™ I-Beam Horizontal Lifeline System
or contact 1-800-328-6146
NIOSH Workplace Solutions Sheet
The National Institute of Safety and Health (NIOSH) has published a series of “Workplace Solutions”, which are easy-to-understand recommendations from NIOSH research results. Related to this Construction Solution, please find more information on:
Preventing Falls from Heights through the Design of Embedded Safety Features and Supporting Prevention through Design (PtD) Using Business Value Concepts
CPWR - The Center for Construction Research and Training
To obtain information, visit Leading Edge Protection System - A Manual for Installation and Use
or contact 1-301-578-8500
