Posted By Gordon Thelwell
Hi Roy, hope this helps.
As a rule of thumb, i always consider that if a person is working at a height that would allow them to tansverse their body height and land on their head, then they need some sort of restraint.
WORKING AT HEIGHT
Falls are the largest cause of accidental death in the construction industry. They account for 50% of all fatalities. Most accidents involving falls could have been prevented if the right equipment had been provided and properly used. All falls need to be prevented. However, specific precautions need to be taken (guard rails, barriers, etc) where it is possible to fall two metres (2 m) or more. Even if the fall is less than 2 m, it may be necessary to protect the worker, for example if they are working above starter-bars - assess the risk.
When planning for work at height, consider where the work will be done. Obviously the first choice will be any existing structure which allows safe access and provides a safe working place. Where it is not possible to work safely from the existing structure, an extra working platform will be needed.
Rules to prevent falls
Don't work at height unless it is essential.
Make sure the working platform is secure. Check that it:
will support the weight of workers using it and any materials and equipment they are likely to use or store on it;
is stable and will not overturn. For example, scaffolds usually need to be tied to a supporting structure. Mobile elevating work platforms (MEWPs) may not be safe on uneven or sloping ground;
provides adequate working space; and
is footed on stable ground or on a stable support or structure.
Provide guard rails, barriers etc at open edges, including edges of floors, floor openings, edges of roofs and edges of working platforms.
The nature or duration of the work may also influence what working platform is most appropriate. Traditionally much work has been done from scaffolding. However, other means of access such as MEWPs, tower scaffolds, personal suspension equipment (such as rope access techniques and boatswain's chairs) and ladders, offer advantages and disadvantages. It is essential to consider what risks there may be in erecting the access equipment as well as using it.
Matters which need to be considered when selecting a type of work platform or means of access to the workplace include:
space available on the site. Each type of platform requires minimum amounts of space, for example, MEWPS need outriggers - can you fit them in?;
the type of work to be carried out, eg will it require heavy loads on the platform?;
how long the work will last;
what risks there will be during erection of the platform;
how difficult the platform will be to maintain;
how many people will need to use the equipment;
can the equipment be stabilised, eg can the scaffold be tied?; and
whether part of the structure can be provided early in the work so that there is a permanent working platform.
Summary of steps to take before working at height
Check there is a safe method of getting to and from the work area.
Decide what particular equipment will be suitable for the job and the conditions on site.
Make sure work platforms and any edges from which people are likely to fall have guard rails and toe boards or other barriers.
Make sure that the equipment needed is delivered to site in good time and that the site has been prepared for it.
Check that the equipment is in good condition and make sure that whoever puts the equipment together is trained and knows what they are doing.
Make sure those who use the equipment are supervised so that they use it properly. The more specialised the equipment (for example, boatswain's chairs and rope access equipment), the greater the degree of training and supervision required to ensure safety.
Check any equipment provided by another company is safe on site before using it.
Find out who to tell if any defects need to be remedied or modifications need to be made and keep them informed.
When selecting a means of access, remember:
only when it is not practicable to provide a work platform with guard rails should other means of access (for example, boatswain's chairs or rope access techniques) be used;
only when no other method is practicable, or risk assessment shows other methods are safer when work platforms cannot comply with all requirements for safe work (eg a guard rail has to be removed to land materials), should a way of arresting falls (for example, a harness and lines or nets) be relied upon;
if no other means of providing a safe place of work at height is available, then appropriately anchored harness should be worn. However, whenever harnesses are used a method must be available to enable people to be rescued should they fall and be left suspended in their harness;
nets may also be needed to protect those working to put guard rails or other protection in place;
ladders should always be secured if possible. They should be primarily used for access and only be used as workplaces to do light work of short duration, and then only if it is safe to do so. It is generally safer to use a tower scaffold or MEWP even for short-term work. Heavy work activity such as drilling or carrying heavy loads should never be carried out from a ladder. When using a ladder ensure that the person on the ladder always has three points of contact, ie two legs and a hand. People should never have to lean sideways when up a ladder.
when selecting a safe system of work at heights, all the risks have to be considered before one method is selected. For example, if nets are selected, is there adequate clearance under the nets to prevent injury to those who may fall into them? If harnesses are used, is there sufficient clearance from the ground to allow the shock absorbing lanyard or inertia reel to fully extend?
before any work at height, check that there is adequate clearance for equipment. For example, overhead power lines can be a risk when erecting scaffolds or using MEWPs; there can be a risk of crushing against nearby structures when mobile access platforms are manoeuvered.
Safe working platforms
Working platforms are the parts of structures, MEWPs, cradles etc upon which people stand while working. As well as being adequately supported and provided with guard rails or barriers, working platforms should be:
wide enough to allow people to pass back and forth safely and to use any equipment or material necessary for their work at that place and in any case, at least 600 mm wide;
free of openings and traps through which people's feet could pass, causing them to trip, fall or be injured in any other way;
constructed to prevent materials from falling. As well as toe boards or similar protection at the edge of the platform, the platform itself should be constructed to prevent any object which may be used on the platform from falling through gaps or holes, causing injury to people working below. For scaffolds, a close-boarded platform would suffice, although for work over public areas, a double-boarded platform sandwiching a polythene sheet may be needed. If MEWPs or cradles are used and they have meshed platform floors, the mesh should be fine enough to prevent materials, especially nails and bolts, from slipping through; and
kept free of tripping and slipping hazards. Where necessary, provide handholds and footholds. Keep platforms clean and tidy. Do not allow mud to build up on platforms.
Mobile and suspended access equipment
Where it is not possible to work from the existing structure and the use of a scaffold working platform is not appropriate, a range of mobile access equipment including mobile elevating work platforms (MEWPs), suspended cradles, mast climbing work platforms (MCWPs), boatswain's chairs or seats, and rope access equipment can be used.
Those using this type of equipment should be trained and competent to operate it. They should learn emergency and evacuation procedures so that they know what to do, for example, if the power to the platform fails, or fire breaks out in the building being worked on. With many pieces of equipment, more than one person will be needed to ensure safe operation.
Before work starts
Check that:
a handover certificate is provided by the installer. The certificate should cover how to deal with emergencies, operate, check and maintain the equipment, and state its safe working load;
equipment is installed, modified and dismantled only by competent specialists;
there is a current report of thorough examination for the equipment;
areas of the site where people may be struck by the platform or falling materials have been barriered off or similar. Debris fans or covered walkways may also be required;
systems are in place to prevent people within the building being struck by the platform as it rises or descends and prevent the platform coming into contact with open windows or similar obstructions which could cause it to tip;
supports are protected from damage (for example, by being struck by passing vehicles or by interference from vandals);
the equipment can be protected from adverse weather. High winds can tilt platforms and make them unstable. Establish a maximum safe wind speed for operation. Storms and snow falls can also damage platforms, so they should be inspected before use after severe weather.
At the end of each day
Check that:
the platform is cleared of tools and equipment;
all power has been switched off and, where appropriate, power cables have been secured and made dead;
the equipment is secured where it will not be accessible to vandals or trespassers;
notices are attached to the equipment warning that it is out of service and must not be used; and
check the shift report for warnings of malfunction etc.
Mobile elevating work platforms (MEWPs)
Mobile elevating work platforms (MEWPs) can provide excellent safe access to high level work. When using a MEWP make sure that:
whoever is operating it is fully trained and competent;
the work platform is provided with guard rails and toe boards or other suitable barriers;
it is used on firm and level ground. The ground may have to be prepared in advance;
its tyres are properly inflated;
any outriggers are extended and chocked as necessary before raising the platform; and
everyone knows what to do if the machine fails with the platform in the raised position.
Do not:
operate MEWPs close to overhead cables or other dangerous machinery;
allow a knuckle, or elbow, of the arm to protrude into a traffic route when working near vehicles;
move the equipment with the platform in the raised position unless the equipment is designed to allow this to be done safely (check the manufacturer's instructions).
Some MEWPs are described as suitable for 'rough terrain'. This usually means that they are safe to use on some uneven or undulating ground - but check their limitations in the manufacturer's handbook before taking them onto unprepared or sloping ground.
Wearing a harness with a fall restraint lanyard attached to the platform can provide extra protection against falls, especially while the platform is in motion.
See also general advice about mobile and suspended access equipment.
Mast climbing work platforms
This equipment is often used when carrying out repairs to or refurbishment of high rise buildings. MCWPs are designed to provide access to working positions - they are not designed to act as material hoists.
Only specialists should erect, alter or dismantle mast platforms. It is particularly important that the correct sequence is followed. Serious accidents have occurred when ties have been removed or outriggers have not been properly extended during alterations.
A great advantage of using mast platforms is that those using them can be protected from adverse weather as many types can be provided with screens and a roof to the platform. Enclosures to platforms can increase wind loads. The supplier must always be consulted before fixing them.
When mast platforms are used, make sure:
masts are rigidly connected to the structures against which they are operating and outriggers are used when necessary;
working platforms are provided with suitable guard rails and toe boards;
the controls only operate from the working platform; and
the area below the platform is barriered off to protect people from objects that may fall from the platform.
See also the general advice about mobile and suspended access equipment.
Temporarily suspended access cradles and platforms
Accidents happen during installation, use and dismantling of temporary cradles. Most accidents happen because of:
unsafe access to and from the cradle;
insufficient or poorly secured counterweights and holding down systems;
failure of the cradle platform or components such as drop nose pins and bolts;
failure of winches, climbing devices, safety gear and ropes usually as a result of poor maintenance; and
failure to follow the manufacturer's instructions on erection and dismantling.
Equipment should be selected, installed, thoroughly examined and tested to ensure that it is suitable for its intended purpose. Cradles should only be used by suitably trained and competent workers.
When using cradles check that:
the cradle has adequate guard rails and toe boards and material cannot fall from or through the cradle's base;
the equipment is capable of fitting closely to the building and where buffers or rollers are fitted, they will run against suitable features on the building;
the building is capable of carrying the loads placed upon it, particularly under the counterweights and under the fulcrum (or pivot point) of the outrigger. The advice of a structural engineer may be needed;
jib spacing matches the cradle length and, when the cradle can move, adequate stops are provided to prevent the cradle running off the end of the track;
jib length and counterweights are specified to give a factor of safety against overturning of no less than three;
a secondary safety rope fitted with a fall arrest device is provided and used;
adequate operating instructions and technical support is available. If the equipment is hired, the supplier should be able to advise;
the cradle is not overloaded and loads are placed on the platform as uniformly as possible;
there is safe access into the cradle. Access at ground level is safest. If access is from the roof, the cradle should be secured to prevent it swinging away from the building. Access must be possible without the need to climb up or down the suspension ropes. Also, if access is from the roof, or other raised platform, suitable means to prevent falls from roof edges will be required (for example, guard rails and toe boards); and
there is a plan for rescuing the operator if the crane fails while at a high level.
Even where these precautions have been taken, accidents are still possible. For example, if a motor of a powered cradle fails, it can make the cradle tip or people may overbalance and fall while reaching out of the cradle. Safety harnesses can save lives in these circumstances. Harnesses should be attached to suitable anchorage points within the cradle or platform (such as the motor mounting points) or attached to running lines rigged in the cradle. The harness lanyards should be kept as short as possible, while allowing operators to reach their place of work. For further advice, see section on harnesses.
It is important that a thorough visual pre-use check for obvious faults is carried out before each use. In addition, a weekly inspection should be carried out by a competent person and a record made of that inspection. See also the general advice about mobile and suspended access equipment. Before taking a temporary scaffold access platform into use, the following should be checked daily:
The platform should be structurally sound: lift it off the ground, say
1 m, and inspect for excessive deflections;
While it is off the ground, carry out a tactile inspection of critical connectors;
Make sure that it runs freely up and down - try it out; and
Check that lines of communication work properly.
At the end of the day/shift, the following at least should be done:
the platform cleared of tools and equipment;
all power switched off and, where appropriate, power cables secured and made dead;
the equipment secured where it will not be accessible to vandals or trespassers;
notices attached to the equipment, warning that it is out of service and must not be used; and
shift report checked for warnings of malfunction etc.
Boatswain's chairs/seats
Boatswain's chairs and seats can be used for light, short-term work. They should only be used where it is not practicable to provide a working platform. In general, use a chair which consists of a seat with a back, a central suspension point and a carrying point for tools.
Whether a chair or seat is used, the user should be attached to the suspension system by a harness and lanyard to protect against falls. See also the general advice about mobile and suspended access equipment.
Rope access techniques
This technique can be used for inspection and some short-term light-duration construction work. It should only be used where access from a working platform is not practicable. Check that:
the equipment is erected under the supervision of a competent person and then a pre-check is carried out;
anyone using the technique has been expertly trained and is competent;
safe descent does not depend upon a single suspension point. Wherever possible the main rope and safety rope should be attached to separate suspension points;
all the equipment is checked carefully before each use and maintained to a high standard;
any tools which are needed for the work are attached to the operator with suitable ropes or chains, so that they cannot be dropped; and
where a risk of dropped tools or falling materials remains the area beneath the work should be fenced off or protected by fans, covered walkways or similar.
See also the general advice on mobile and suspended access equipment.
Safety harnesses
Providing a safe place of work and system of work to prevent falls should always be the first consideration. However, there may be circumstances in which it is not practicable for all or any of the requirements for guard rails etc to be provided (for example, where guard rails are taken down for short periods to land materials) where people may still approach an open edge from which they would be liable to fall 2 m or more, other forms of protection will be needed. In some cases a suitably attached harness and temporary horizontal lifeline could allow safe working.
When using harnesses and temporary horizontal lifelines, remember:
harnesses and lanyards are made of man-made fibres and as such are prone to degradation by sunlight, chemicals etc. It is important to carry out tactile pre-use checks daily, in good light, before taking harnesses and lanyards into use. If there is the slightest doubt about a harness or the lanyard, do not use it. Faults can be noticed by discolouration, little tears and nicks, grittiness to touch etc.
a harness will not prevent a fall - it can only minimise the risk of injury if there is a fall. The person who falls may be injured by the impact load to the body when the line goes tight or when they strike against parts of the structure during the fall. An energy absorber fitted to the energy-absorbing lanyard can reduce the risk of injury from impact loads;
minimise free-fall distance. Keep your anchor as high as posssible, thus reducing fall distances.
consider how to recover anyone who does fall;
anyone who needs to attach themselves should be able to do so from a safe position. They need to be able to attach themselves before they move into a position where they are relying on the protection provided by the harness;
the energy-absorbing lanyard should be attached above the wearer where possible. Extra free movement can be provided by using running temporary horizontal lifelines or inertia reels. Any attachment point must be capable of withstanding the impact load in the event of a fall - expert advice may be needed;
to ensure that there is an adequate fall height to allow the system to deploy and arrest the fall;
a twin lanyard may be necessary in some cases where the wearer needs to move about. A twin lanyard allows the wearer to clip on one lanyard in a different position before unclipping the other lanyard;
installation of equipment to which harnesses will be fixed, eg a suitable anchor, must be supervised by a suitably qualified person; and
make sure everyone who uses a harness knows how to check, wear and adjust it before use and how to connect themselves to the structure or safety line as appropriate. Each day, harnesses and lanyards need to be inspected visually, before they are used, for signs of abrasion, tears or general wear and tear. They should be thoroughly examined periodically, and these examinations should be carried out at least every six months.
Protection against falling materials
The risk of falling materials causing injury should be minimised by keeping platforms clear of loose materials. In addition, provide a way of preventing materials or other objects rolling, or being kicked, off the edges of platforms. This may be done with toe boards, solid barriers, brick guards, or similar at open edges. If the scaffold is erected in a public place, nets, fans or covered walkways may be needed to give extra protection for people who may be passing below. High-visibility barrier netting is not suitable for use as a fall prevention device.