APPLICATIONS
		Access Platforms, Stairs, & Gangways
		Roof Top Fall Protection
		Guardrails
		Catwalks
		Crane Rail
		Confined Space & Rescue
		Horizontal Lifelines
		Vertical Lifelines & Ladders
		Personal Protective Equipment
	INDUSTRY
		Truck Fleet
		Steel & Foundry
		Machine Guard
		General Industry
		Municipalities
		Oil – Gas – Petrochemical
		Construction
		Aircraft Hangars
		Rail Car
	PRODUCTS
		Uni-Track
		Single Point Anchors
		Uni-Grab / Uni-Ridge
		Swing Gates
		Roof Hatch System

Horizontal Lifelines For Fall Arrest and Fall Restraint

Horizontal lifelines, also known as HLL systems, are important components in many of the fall arrest and fall restraint systems installed by DFP. Horizontal lifelines are common in work areas lacking overhead anchor points available for personnel tie–off. In its simplest form, the horizontal lifeline consists of a cable attached to two or more anchor points on a roof-top, crane runway, bridge or outdoor construction site, or any other elevated work area that poses a fall risk to personnel. When used in combination with personal protective equipment, a horizontal lifeline can arrest a fall, limiting the amount of force that is transferred both to the worker and the fall arrest system.

An OSHA compliant horizontal lifeline provides safe roof top access for maintenance and repair of a lighting system.

This same combination of horizontal lifeline, body harness, and lanyard can also function as a fall restraint system, limiting the At Risk Worker’s (AWR) ability to move close enough to fall over an unprotected edge. The fall restraint and fall arrest properties of horizontal lifelines make the HLL an integral part of many fall protection systems.

Advantages of Horizontal Lifelines

Horizontal lifelines can offer significant advantages over fabricated steel fall protection systems. Horizontal lifelines do not require the costly and time consuming fabrication and installation associated with steel platforms, walkways, and guard rail systems. HLL’s are lighter than fabricated steel solutions and impart smaller footprints on elevated work spaces. Constructed from stainless steel components, horizontal lifelines offer corrosion resistance and exceptional component longevity. Finally, fall protection safety specialists can design a horizontal lifeline system to accommodate the special characteristics of your elevated work space, from corners to the absence of pre-existing anchor points and more.

Horizontal Lifeline Applications

• + Bridge Maintenance
• + Construction
• + Structural Steel Erection
• + Roofing / Roof Top Maintenance
• + Window Washing
• + Railcar
• + Overhead Cranes
• + Aircraft Hangars
• + Loading Docks
• + Temporary Construction

AT DFP, we recognize that each fall protection scenario is unique, requiring a comprehensive hazard assessment and customized solution. From permanent HLL installations, to temporary, reusable, portable solutions, our safety engineers have the experience needed to help you fully comply with all OSHA fall protection regulations.

Compliance and Horizontal Lifeline Systems By Matthew Blackford

A horizontal lifeline (HLL) is a flexible line rigged in a horizontal plane secured at each end to an anchorage providing an effective fall protection solution for work requiring horizontal mobility along elevated surfaces. A worker connects to the line using a personal fall arrest system that moves with the worker between the two anchorages. By providing a sliding connection along the entire walkway the anchorage is kept overhead, reducing the hazard of dangerous swing falls that can occur if the worker moves to a location where the anchorage is no longer directly overhead.

Although installing a horizontal lifeline may appear to be as simple as stringing a line between two supports, determining the loads applied to the anchorages and the clearance required below the working surface in the event of a fall can be extremely complicated. In this respect horizontal lifelines are one of the most complex types of fall protection equipment.

To further complicate matters for the safety engineer, no U.S. standards currently address specific performance requirements for horizontal lifeline systems. Consequently, designers and manufactures are able to install systems as they see fit. It also puts the responsibility of determining what constitutes a safe system in the hands of the end user. It is important for the employer or safety engineer to understand the different types of HLLs that are available and the limitations of each type in order to make an educated decision during the selection process.

Horizontal Lifeline Classification

HLL systems may be classified as either permanent or temporary. A permanent HLL becomes an integral part of the anchoring structure and should be designed to function for an extended period of time. Permanent HLLs are usually constructed of metal components. Most synthetic fiber ropes are not resistant to long-term ultraviolet and environmental exposure.

Temporary HLL systems are pre-engineered packaged systems that should be supplied with complete instructions for installation and use, including the number of users allowed to be connected, the maximum allowable span length, clearance requirements and anchorage requirements. They are designed to be used for a short period of time, usually for protection during construction. When the project is complete the HLL can be removed and re-used at the next project. Both steel cable and synthetic rope are common materials used for temporary HLL systems.

HLLs can be also be classified as either single span or multi-span. This classification is independent of the system being permanent or temporary. The simplest type of HLL is a single span. Single span HLLs are limited in length by their dynamic deflection. Long spans result in large deflections that may not prevent the worker from hitting the ground in most applications. Having only two anchorage points, single span HLLs are limited to a straight line.

Multi-span HLL systems are not limited in length since they are supported at intermediate anchorages. The basic method of constructing a multi-span HLL is to thread the line through eye bolts or holes in the intermediate anchorages. This requires the worker to use a double-legged lanyard to "leap frog" across the intermediate supports to remain connected at all times. An additional disadvantage of this type of system is that the line must be within reach of the workers, which is impractical for applications such as railcar loading where setback requirements would place the lifeline beyond reach.

A more sophisticated type of multi-span HLL uses a specially designed intermediate bracket that retains the cable, but allows a special connector to pass over the bracket keeping the worker connected at all times. This could either involve routing the connector through an "S" shaped path that retains the line or a bracket and slider arrangement that allows hands-free bypass without requiring any action from the worker. Some of the available proprietary multi-span HLL systems can accommodate direction changes to make corners or bend around and under obstructions such as grain loading spouts and roof stacks.

The complexity and infinite number of configurations of a multi-span HLL system re-quires the use of a computer simulation to accurately calculate the system performance. The computer model must be backed up by "real world" testing to verify its accuracy.

Design Issues

Having a fall protection system in place does not necessarily mean employees are protected in the event of a fall. When and if a fall occurs the employer should be confident that the fall protection system is properly anchored and will prevent the worker from hitting an obstruction or lower level before the fall has been completely arrested.

Two primary factors must be considered in designing a horizontal lifeline.

• + The loads that are applied to the anchorages during a fall arrest situation must be known to design or verify the strength of the anchorages.
• + The deflection of the lifeline during a fall arrest situation must be known to ensure the worker will not contact an obstruction or lower level.

The deflection and loads are closely related. They are a function of several factors including the pre-tension in the lifeline, total length of the lifeline, length of the intermediate spans, number of workers connected and the properties of the lifeline material.

Anchorage requirements

The dynamic loads at the end terminations of a HLL system can be several times higher than the arresting force generated by the falling worker. This is a function of the geometry of a horizontal line during fall arrest. OSHA 29 CFR Part 1926, Subpart M, Appendix C states:

"Horizontal lifelines may, depending on their geometry and angle of sag, be subjected to greater loads than the impact load imposed by an attached component. When the angle of horizontal lifeline sag is less than 30 degrees, the impact force imparted to the lifeline by an attached lanyard is greatly amplified. For example, with a sag angle of 15 degrees, the force amplification is about 2:1 and at 5 degrees sag, it is about 6:1. Depending on the angle of sag and the line's el as-ti city, the strength of the horizontal lifeline and the anchorages to which it is attached should be increased a number of times over that of the lanyard."

This statement is taken from non-mandatory guidelines for complying with the mandatory requirements of Part 1926.502. It provides an overview of the relationship between the dynamic deflection and end loads of HLLs, but is not intended to provide any strength requirements for anchorages.

The specific requirements for HLLs in Part 1926.502(d)(8) state:

"Horizontal lifelines shall be designed, installed, and used, under the supervision of a qualified person, as part of a complete personal fall arrest system, which maintains a safety factor of at least two."

This paragraph clearly dictates that HLLs must be designed by a qualified engineer or manufacturer that has experience designing such systems. It also gives the engineer guidance for designing anchorages or stanchions that will be supporting the system. It does not give quantitative values for anchorage strength. The designer or manufacturer of a HLL system must provide documentation of the loads on the system for the purpose of designing or verifying the strength of the anchorages. The designer or manufacturer must also specify what type of equipment may be used in conjunction with the HLL as a complete system.

The load requirement for HLLs is often confused with the 5,000 pound OSHA requirement for personal fall arrest systems. For example, if the maximum arresting force on a worker’s lanyard is 1,800 pounds, each support must sustain a 1,800 vertical load, but also a horizontal load at the end anchorages that could be much greater than 1,800 pounds. Assume the end loads are three times the load on the worker’s lanyard, or 5,400 pounds, which is reasonable considering the information presented relating the dynamic deflection to the end loads. The required anchorage strength would be 10,800 pounds applying the requisite safety factor of two. This example illustrates how a 5,000 pound requirement for end anchorages would be inadequate for most HLL installations.

Clearance Requirements

The other primary factor that is critical to the design of HLL systems is calculating the dynamic deflection of the lifeline. Other factors that must be accounted include freefall of the worker, the deceleration distance of the worker’s shock-absorbing la n-yard or retractable lifeline and any other considerations that increase the worker’s fall distance. The sum of these factors must not be so great that the worker can contact an obstruction or lower level. The designer or manufacturer of a HLL system should provide a recommended minimum clearance value for permanently installed HLL systems and a method of calculating minimum clearances for temporary systems that can be installed in multiple configurations.

Evaluating Systems

When selecting a horizontal lifeline system there are several issues that should be considered.

• + Safety. The purpose of the system is to protect people from fall injuries. Other features are irrelevant if the system cannot do the job for which it is intended. Look for suppliers that are experienced in horizontal lifeline design.
• + Ease of use. Consider the type of work being done and determine which system will be the least cumbersome for the worker. If the system makes work inefficient it's more likely that the employee will choose to work unprotected.
• + Length of service. The system should be appropriate to the expected term of use. Using a temporary lifeline in a permanent installation may put employees at risk. The strength of the materials may be reduced by long-term environmental exposure.
• + Environment. Make certain the materials a suitable for use in harsh environments if there is exposure to corrosive agents, elevated temperatures or other severe conditions.
• + Adequate coverage. The primary advantage of a horizontal lifeline over a single point anchorage is the mobility it provides and the increased protection from swing falls. If the lifeline ends short of the work area the worker could be at risk of a swinging collision.
• + Performance data. Performance data should be provided as part of any complete fall protection system.
• + Training. Thorough instructions and on-site training ensures that the workers using the equipment know how to use the equipment safely.

Matthew Blackford is an R&D Engineer for DBI/SALA, 3965 Pepin Avenue, Red Wing, MN 55066; (800) 328-6146; Fax: (651) 388-5065

Horizontal lifeline with rope grab kit and fall protection skylight screens.

Mounted to a corrugated roofing material, a horizontal lifeline offers safe for roof top access.

Single Source Turnkey Responsibility

You receive single source responsibility for the design, engineering, fabrication, installation, training and certification of permanent and temporary fall arrest and fall protection equipment.

Fall Protection / Fall Prevention Training Programs

Glossary

FAQs

OSHA Fall Protection Compliance