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Height Safety Under Construction

Published: 22nd Aug 2012

In the construction industry in the US, falls are the leading cause of worker fatalities. Each year, on average, between 150 and 200 workers are killed and more than 100,000 are injured as a result of falls at construction sites.

Management failure

Since we began work records, construction is the industry that carries the most concerns about height for employees. Accident reports show common situations where falls from height occur and illustrate that these events are usually due to poor management control, rather than equipment failure.

The most common factors involve failure to:

• Recognise a problem

• Provide safe systems of work

• Ensure that safe systems of work are followed

• Provide adequate information, instruction, training or supervision

• Use appropriate equipment

• Provide safe equipment Types of falls:

• Falls from ladders

• Falls from machinery

• Falls through roof lights

Falls through fragile roofs

Problem solving

OSHA recognises that accidents involving falls are generally complex events, frequently involving a variety of factors. Consequently, the standard for fall protection deals with both the human and equipment-related issues in protecting workers from fall hazards. For example, employers and employees need to do the following:

• Where protection is required, select fall protection systems appropriate for given situations

• Use proper construction and installation of safety systems

• Supervise employees properly

• Use safe work procedures

• Train workers in the proper selection, use, and maintenance of all protection systems

OSHA has revised its construction industry safety standards and developed systems and procedures designed to prevent employees from falling off, onto, or through working levels and to protect employees from being struck by falling objects. The performance-oriented requirements make it easier for employers to provide the necessary protection. The rule identifies areas or activities where fall protection is needed. These include, but are not limited to, ramps, runways, and other walkways; excavations; hoist areas; holes; formwork and reinforcing steel; leading edge work; unprotected sides and edges; overhand bricklaying and related work; roofing work; precast concrete erection; wall openings; residential construction; and other walking/working surfaces. The rule sets a uniform threshold height of six feet (1.8 m), meaning that construction employers must protect their employees from fall hazards and falling objects whenever an employee is at or above this level. Protection must also be provided for construction workers who are exposed to the hazard of falling into dangerous equipment. The OSHA rule clarifies what an employer must do to provide fall protection for employees, such as identifying and evaluating fall hazards and providing specific training. Requirements to provide fall protection for workers on scaffolds and ladders and for workers engaged in steel erection of buildings are covered in other subparts of OSHA regulations.

Controlled Access Zones

A Controlled Access Zone is a work area designated and clearly marked in which certain types of work (such as overhand bricklaying) may take place without the use of conventional fall protection systems - a guardrail, personal arrest or safety net - to protect the employees working in the zone. Controlled Access Zones are used to keep out workers other than those authorised to enter work areas from which guardrails have been removed. Where there are no guardrails, masons are the only workers allowed to enter. Controlled Access Zones, when created to limit entrance to areas where leading edge work and other operations are taking place, must be defined by a control line or by any other means that restrict access. Control lines should consist of ropes, wires, tapes or equivalent materials, and supporting stanchions. Each must be:

• Flagged or otherwise clearly marked at not more than six foot (1.8 m) intervals with high-visibility material

• Rigged and supported in such a way that the lowest point (including sag) is not less than 39 inches (one metre) from the walking/working surface, and the highest point is not more than 45 inches (1.3 m) - nor more than 50 inches (1.3 m) when overhand bricklaying operations are being performed - from the walking/working surface

• Strong enough to sustain stress of not less than 200 pounds (0.88 kilonewtons)

• Control lines should extend along the entire length of the unprotected or leading edge and should be approximately parallel to the unprotected or leading edge

• Control lines also must be connected on each side to a guardrail system or wall When control lines are used, they should be erected not less than six feet (1.8 m) nor more than 25 feet (7.6 m) from the unprotected or leading edge, except when precast concrete members are being erected. In the latter case, the control line is to be erected not less than six feet (1.8 m) nor more than 60 feet (18 m), or half the length of the member being erected - whichever is less - from the leading edge. Controlled Access Zones, when used to determine access to areas where overhand bricklaying and related work are taking place, are to be defined by a control line erected not less than ten feet (3 m) nor more than 15 feet (4.6 m) from the working edge. Additional control lines must be erected at each end to enclose the controlled access zone. Only employees engaged in overhand bricklaying or related work should be permitted in the Controlled Access Zones. On floors and roofs where guardrail systems are not in place prior to the beginning of overhand bricklaying operations, Controlled Access Zones should be enlarged as necessary to enclose all points of access, material handling areas, and storage areas. On floors and roofs where guardrail systems are in place, but need to be removed to allow overhand bricklaying work or leading edge work to take place, only that portion of the guardrail necessary to accomplish that day's work should be removed.

Systems and practises

1. Guardrail systems Guardrail systems should be surfaced to protect workers from punctures or lacerations, and to prevent clothing from snagging. The ends of top rails and midrails must not overhang terminal posts, except where such overhang does not constitute a projection hazard. When guardrail systems are used at hoisting areas, a chain, gate, or removable guardrail section must be placed across the access opening between guardrail sections when hoisting operations are not taking place. At holes, guardrail systems must be set up on all unprotected sides or edges. When holes are used for the passage of materials, the hole should not have more than two sides with removable guardrail sections. When the hole is not in use, it must be covered or provided with guardrails along all unprotected sides or edges. If guardrail systems are used around holes that are used as access points (such as ladderways), gates must be used or the point of access must be offset to prevent accidental walking into the hole. If guardrails are used at unprotected sides or edges of ramps and runways, they must be erected on each unprotected side or edge. Midrails, screens, mesh, intermediate vertical members, solid panels, and equivalent structural members should be capable of withstanding a force of at least 150 pounds (667 newtons) applied in any downward or outward direction at any point along the midrail or other member. 2. Personal fall arrest systems These consist of an anchorage, connectors, and a body belt or body harness and may include a deceleration device, lifeline, or suitable combinations. If a personal fall arrest system is used for fall protection, it must do the following:

• Limit maximum arresting force on an employee to 900 pounds (four kilonewtons) when used with a body belt

• Limit maximum arresting force on an employee to 1,800 pounds (eight kilonewtons) when used with a body harness • Be rigged so that an employee can neither free fall more than 1.8 m, nor contact any lower level

• Bring an employee to a complete stop and limit maximum deceleration distance an employee travels to 1.07 m

• Have sufficient strength to withstand twice the potential impact energy of an employee free falling a distance of 1.8 m, or the free fall distance permitted by the system, whichever is less Personal fall arrest systems must be inspected prior to each use for wear damage and other deterioration. Defective components must be removed from service. Dee-rings and snaphooks must have a minimum tensile strength of 5,000 pounds (22.2 kilonewtons). Dee-rings and snaphooks should be proof-tested to a minimum tensile load of 3,600 pounds (16 kilonewtons) without cracking, breaking, or suffering permanent deformation.

Snaphooks should be sized to be compatible with the member to which they will be connected, or be of a locking configuration. Unless the snaphook is a locking type and designed for the following connections, they should not be engaged a) directly to webbing, rope or wire rope; b) to each other; c) to a dee-ring to which another snaphook or other connecter is attached; d) to a horizontal lifeline; or e) to any object incompatible in shape or dimension relative to the snaphook, thereby causing the connected object to depress the snaphook keeper and release unintentionally. OSHA considers a hook to be compatible when the diameter of the dee-ring to which the snaphook is attached is greater than the inside length of the snaphook when measured from the bottom (hinged end) of the snaphook keeper to the inside curve of the top of the snaphook. Thus, no matter how the dee-ring is positioned or moved (rolls) with the snaphook attached, the dee-ring cannot touch the outside of the keeper, thus depressing it open. As of January 1, 1998, the use of non-locking snaphooks was prohibited. On suspended scaffolds or similar work platforms with horizontal lifelines that may become vertical lifelines, the devices used to connect to a horizontal lifeline should be capable of locking in both directions on the lifeline. Horizontal lifelines should be designed, installed, and used under the supervision of a qualified person, as part of a complete personal fall arrest system that maintains a safety factor of at least two. Lifelines should be protected against being cut or abraded. Ropes and straps (webbing) used in lanyards, lifelines, and strength components of body belts and body harnesses should be made of synthetic fibres. Anchorages should be designed, installed, and used under the supervision of a qualified person, as part of a complete personal fall arrest system that maintains a safety factor of at least two, e.g. capable of supporting at least twice the weight expected to be imposed upon it. 3. Positioning device systems These body belt or body harness systems should be set up so that a worker can free fall no further than two feet (0.6 m). They should be secured to an anchorage capable of supporting at least twice the potential impact load of an employee's fall or 3,000 pounds (13.3 kilonewtons), whichever is greater. Requirements for snaphooks, dee-rings, and other connectors used with positioning device systems must meet the same criteria as those for personal fall arrest systems. 4. Safety net systems Safety nets must be installed as close as practicable under the walking/working surface on which employees are working and never more than 30 feet (9.1 m) below such levels. Defective nets should not be used, so they should be inspected at least once a week for wear, damage, and other deterioration. The maximum size of each safety net mesh opening should not exceed 36 square inches (230 cm2) nor be longer than six inches (15 cm) on any side, and the openings, measured centre-to-centre, of mesh ropes or webbing, should not exceed six inches (15 cm). All mesh crossings should be secured to prevent enlargement of the mesh opening. Each safety net or section should have a border rope for webbing with a minimum breaking strength of 5,000 pounds (22.2 kilonewtons). Connections between safety net panels should be as strong as integral net components and be spaced no more than six inches (15 cm) apart. Install safety nets with sufficient clearance underneath to prevent contact with the surface or structure below. When nets are used on bridges, the potential fall area from the walking/working surface to the net shall be unobstructed. Safety nets must extend outward from the outermost projection of the work surface as follows: Safety nets should be capable of absorbing an impact force of a drop test consisting of a 400 pound (180 kg) bag of sand 30 inches (76 cm) in diameter, dropped from the highest walking/working surface at which workers are exposed, but not from less than 42 inches (1.1 m) above that level. Items that have fallen into safety nets including, but not restricted to, materials, scrap, equipment, and tools, must be removed as soon as possible, and at least before the next work shift. 5. Warning line systems Warning line systems consist of ropes, wires, or chains, and supporting stanchions and are set up as follows:

• Flagged at not more than 1.8 m intervals with high-visibility material

• Rigged and supported so that the lowest point (including sag) is no less than 0.9 m from the walking/working surface and its highest point is no more than 1 m from the walking/working surface

• Stanchions, after being rigged with warning lines, should be capable of resisting, without tipping over, a force of at least 16 pounds (71 newtons) applied horizontally against the stanchion, 0.8 m above the walking/working surface, perpendicular to the warning line and in the direction of the floor, roof, or platform edge

• The rope, wire, or chain should have a minimum tensile strength of 500 pounds (2.22 kilonewtons) and after being attached to the stanchions, must support, without breaking, the load applied to the stanchions as prescribed above

• The rope, wire, or chain should be attached to each stanchion in such a way that pulling on one section of the line between stanchions will not result in slack being taken up in the adjacent section before the stanchion tips over Warning lines should be erected around all sides of roof work areas. When mechanical equipment is being used, the warning line should be erected not less than 1.8 m from the roof edge, parallel to the direction of mechanical equipment operation, and not less than 3 m from the roof edge perpendicular to the direction of mechanical equipment operation. When mechanical equipment is not being used, the warning line must be erected not less than 1.8 m from the roof edge. 6. Covers Covers located in roadways and vehicular aisles must be able to support at least twice the maximum axle load of the largest vehicle to which the cover might be subjected. All other covers must be able to support at least twice the weight of employees, equipment, and materials that may be imposed on the cover at any one time. To prevent accidental displacement resulting from wind, equipment, or workers’ activities, all covers must be secured. All covers should also be colour coded, or bear the markings ‘HOLE or ‘COVER’.

Protection from falling objects

When guardrail systems are used to prevent materials from falling from one level to another, any openings must be small enough to prevent passage of potential falling objects. No materials or equipment except masonry and mortar should be stored within 1.2 m of working edges. Excess mortar, broken or scattered masonry units, and all other materials and debris should be kept clear of the working area by removal at regular intervals. During roofing work, materials and equipment should not be stored within 1.8 m of a roof edge unless guardrails are erected at the edge, and materials piled, grouped, or stacked near a roof edge must be stable and self-supporting.

Canopies

When used as protection from falling objects canopies must be strong enough to prevent collapse and to prevent penetration by any objects that may fall onto them.

Toeboards

When toeboards are used as protection from falling objects, they must be erected along the edges of the overhead walking/working surface for a distance sufficient to protect persons working below. Toeboards should be capable of withstanding a force of at least 50 pounds (222 newtons) applied in any downward or outward direction at any point along the toeboard. They should be a minimum of 9 cm tall from their top edge to the level of the walking/working surface, have no more than 0.6 cm clearance above the walking/working surface, and be solid or have openings no larger than 2.5 cm in size. Where tools, equipment, or materials are piled higher than the top edge of a toeboard, panelling or screening must be erected from the walking/working surface or toeboard, to the top of a guardrail system's top rail or midrail, for a distance sufficient to protect employees below.

Training

Employers must provide a training programme that teaches employees who might be exposed to fall hazards how to recognise such hazards and how to minimise them. Employees must be trained in the following areas:

• The nature of fall hazards in the work area

• The correct procedures for erecting, maintaining, disassembling, and inspecting fall protection systems

• The use and operation of Controlled Access Zones and guardrail, personal fall arrest, safety net, warning line, and safety monitoring systems

• The role of each employee in the safety monitoring system when the system is in use

• The limitations on the use of mechanical equipment during the performance of roofing work on low-sloped roofs

• The correct procedures for equipment and materials handling and storage and the erection of overhead protection

• Employees’ role in fall protection plans Employers must prepare a written certification that identifies the employee trained and the date of the training. The employer or trainer must sign the certification record. Retraining also must be provided when necessary.

Conclusion

There’s no doubt that training is of central importance where it comes to establishing safe work practises at height, but creating the infrastructure for this is a factor employers cannot afford to ignore. Many elements need to weighed into the balance, from choosing appropriate fall protection systems to conducting a thorough risk assessment in the first place - and they all need to be weighed before one of your employees loses his balance and falls. It is hoped that the essentials to this vital process outlined in this article will go some way to reducing fatalities from such falls.

Published: 22nd Aug 2012 in Health and Safety Middle East

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