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Construction Health and Safety Management By Dr Simon Smith – licensed under the Creative Commons Attribution – Non- Commercial – Share Alike License
Part 8: Working at Height Construction Health & Safety Management Simon Smith (University of Edinburgh) & Philip Matyear (Balfour Beatty)
Overview General Legislation HSE view Working at height examples Hierarchy of control Eliminate work at height Planning for working at height Assess to height Access from height Protection measures Edge Protection Lift shafts - Safety Alert Safety harnesses Inspection and Maintenance Summary Further reading
General Source - HSE Statistics of fatal Injuries 2002 / 03
Legislation - Principle Requirements Health and Safety at Work Act etc 1974 Management of Health and Safety at Work Regs 1999 Construction, Design and management Regs 1995 Construction (Health, safety and welfare) Regs 1996 Provision and use of work equipment Regs 1998
HSE view HSC press release C044: September 2003 HSE LOOKING AT SAFE WORK AT HEIGHT All work at height has been identified Work at height has been eliminated where possible Where elimination is not possible, the correct equipment has been selected Work platforms have been installed with adequate access If using mobile elevated work platforms (MEWPs), they are used correctly If using tower scaffolds, they are correctly erected with edge protection and toeboards as necessary
HSE view Ladders or step ladders are only being used for short duration work, that they are the correct type for that work and are secured to prevent slipping If using safety harnesses, they have suitable anchorages and adequate fall distances and are inspected, and All work at height equipment, including ladders and step-ladders, have been inspected, examined and maintained as necessary. In addition, inspectors will look to ensure that only competent contractors are used for work at height and that all jobs have been properly planned and thought through.
What to avoid
Working at Height At some stage during most construction and maintenance projects there are some tasks that involve working at height - here are some examples. Structural SteelRoofworkCladding & Glazing ScaffoldFalsework Deep Excavations
The hierarchy of control Eliminate working at height The best way of controlling any hazard is to remove it ! Measures that designers can consider include; òUse of prefabrication to limit the risks arising from working at height ò Detail early access requirements to permit their early construction. ò Detail slabs or hardstandings to suit scaffolding and mobile access equipment ò Design the structure for scaffold, safety nets, running lines or safety harnesses. ò Design permanent access facilities to ease access for maintenance of the structure over its life. ò Select materials that will reduce the risks during maintenance e.g specifying non -fragile roofing materials.
The hierarchy of control Planning for work at height In reality there will always be elements of work at height in the life cycle of any building - Construction, Maintenance and Demolition. Architects and designers are constantly pushing construction boundaries driven by the clients brief for unique and unusual buildings / structures. Its because of this, and the very nature of buildings that working at height will never be completely designed out and so the need to plan and execute the work in a controlled manner remains. Urbis - Manchester New Lowry Gallery - Manchester
The hierarchy of control Planning for work at height 4 Ws & 1 H Who - What trades, How many, How many need work positions? What - Type of work - demolition / construction, Quantities of materials, Tools required? Where - At what height will people be working, Is the job built in-situ or by prefabrication? Is access from the ground available, Environmental hazards that could limit access options. When - Can a particular task be scheduled to make use of permanent access arrangements or by adopting existing temporary access, Will a particular order of doing the work make the access needed for carrying out the task easier or more difficult. How - How long is access required, Will continuous access be required for months, Will access be required later in the programme for following trades, testing and inspection etc.
Access to height - Static Work Platforms Having established the need for a working platform your next decision is what type, here is a list of current options including their common uses and limitations Independent Tied Scaffold For - Provides a good working platform for a variety of trades - very adaptable. Limitations - Restricts access at ground level, relies on structure for its stability. Preston PrisonCrawshaw School, Pudsey
Access to height - Static Work Platforms Birdcage Scaffold For - Provides access and a working platform below ceilings and soffits, for M & E installation and finishing trades. Limitations - Restricts access in the space below, normally have one working deck fully boarded and are suitable for light work only.
Access to height - Static Work Platforms Truss - Out and Cantilever Scaffold For - Where an independent scaffold cannot be erected from ground level. Limitations - Needs a specific design, potentially hazardous to erect, inspect and dismantle. Simple truss outs and cantilevers are intended for very light work only and should not be loaded with materials unless designed accordingly. Its good practise to mark safe working load on these two types of scaffold Truss-out scaffold Cantilever Scaffold
Tower Scaffolds For - M & E installation and other finishing trades such as painters - typically short duration work in many locations. Limitations - Needs a firm level surface and is restricted in height by base dimensions. Types include;- Prefabricated Aluminum Alloy System Scaffold Traditional Tube and Fittings Glass Reinforced Plastic (GRP) Height to Base Ratio Outside Use : - 3 : 1 Inside use : -3.5 : 1 ! Towers must be erected by a competent person ! Access to height - Static Work Platforms
Mobile Elevated Work Platforms (MEWP ’ s) For - Used for M & E installation, steelwork connections, finishing, maintenance and inspections. Limitations - Ground conditions, Reach / length of boom Restricted loads in basket. Types include;- Scissor Lift Articulated Boom Trailer Mounted ! MEWP’s must be operated by a competent person ! Access to height - Mobile Work Platforms
Mast Climbing Work Platforms (MCWPs) For - Repetitious work at different levels in one location finishing, cladding and maintenance. Limitations - Need suitable ground conditions, trained operator, requires tying in at height. MCWP ’ s - consist of three main components: Mast or towers which support the work platform Platform capable of carrying persons and equipment Chassis supporting tower/mast structure Access to height - Mobile Work Platforms
Access to height - Other Ladders To be used for light, short duration work only (That’s Minutes - Not Hours!) To rest on a stable, firm and level surface Project at least 1.0m above working platform ( 5 rungs) Set at an angle of 1 : 4 (approximately 75 degrees) When used as part of an access platform tied securely by the stiles. Inspected on a regular basis as part of the scaffold inspections Ref : - Construction (Health, Safety and Welfare) Regs 1996, Regulation 6, Schedule 5.
Access to height - Other Step Ladders Stepladders provide a free standing means of access. They require more careful use as they are not designed for any degree of side loading and are more easily overturned. Accidents with step ladders occur for similar reasons for those with ladders but with the additional hazard of people standing on the top platform. Work should never be undertaken from the top platform which should be used for tool, bucket and paint storage only.
Access to height - Other Trestles A common piece of equipment found on most construction sites and used mainly by finishing trades such as plasters and painters. Easy to set up and often miss used. Common problems with trestles include; Scaffold boards not supported at correct centre’s (commonly 1.2m). Overloaded platforms, No provision for proper access - Ladder etc Too often used instead of a proper scaffold working platform!
Access from height Man Riding Skips For - Short duration work at high level or below ground typically for steelwork connections, inspections and maintenance. Limitations - Needs a suitable crane. Checks All lifting equipment has been tested and holds a valid test certificate within the last 6 months. Operative in manrider should wear a harness that is attached directly to the crane block
Slung Scaffolds For - High level work on ceilings and soffits - work above railways, roads or operating factories Limitations - Limited safe working load, attachment points, needs a specific design, potentially hazardous to erect, inspect and dismantle. Access from height
Cradles, Bosun ’ s Chairs and Abseiling For - Painting, inspection and maintenance, sometimes used in conjunction with abseiling techniques. Limitations - Limited safe working load, need to train operators and require highly skilled and trained operatives for abseiling, restricted work area. Access from height
Protection Measures Fall Arrest - Safety Nets A passive fall arrest system comprising of a series of safety nets tied and supported on the new structure / scaffold. For - Versatile fall protection for the safe installation of pre- cast sheets. Limitations - Safety nets can be difficult to rig - must be installed by trained personnel, they require suitable anchor points, regular inspections and allowances for sag / falls must be considered.
Protection Measures Fall Arrest - Air Mats A passive fall arrest system comprising of a series of connected air bags. For - Offers a quick, versatile fall protection for the safe installation of pre-cast concrete floor sections, beam and block floors, and roof trusses. Limitations - Must be installed directly below the floor being laid - to keep potential fall distances to a minimum, can damage new block work if installed to early.
Protection Measures Edge Protection The primary means of achieving safety when working at height is to provide adequate access arrangements and working platforms with good edge protection - Schedules 1 & 2 of the Construction (Health, Safety and Welfare) Regs set out the requirements for edge protection and working platforms. Crawshaw High School, Pudsey
Protection Measures - Lift Shafts Figure 1 Figure 2 The erection of scaffold to an internal shaft as the shaft is to be fully boarded including hop-up brackets and boards where required. Minimum double guard rail and toe board must be installed at all shaft openings as a shaft is constructed. This arrangement will allow any viewing of a shaft interior by personnel to take place at early stages prior to internal fitting. No other protection arrangement is to be accepted and flush ‘boarding up’ is not an acceptable practice. For lifts, as soon as practicable a lift shaft installer shall fit proprietary temporary lift doors at every floor opening. (see Figs 1&2 for examples).
Remember fall arrest systems do not prevent falls, but can reduce injury once a fall has happened. There are two basic types: Those that give general protection: Passive Safety nets, Air Mats and Crash Decks once properly installed can protect everyone within the area of protection Those giving individual protection: Active Safety harness attached to suitable anchorage point or running line. Harnesses need to be suitable for the individual, who should be trained to fit and use them. Protection Measures
Inspection and Maintenance It is vital that access and fall arrest equipment are regularly inspected and maintained so that they remain fit for purpose through out the construction period to ensure: No person or materials can fall from access ways and working platforms the access equipment remains stable with no danger of collapse fall arrest equipment is undamaged or affected such that it could impair performance. Working platforms, suspension equipment and safety nets must be inspected: before being taken into use for the first time, after any substantial alteration, after an event likely to have affected its strength or stability and at regular intervals not exceeding 7 days
Inspection and Maintenance
Summary There is no such thing as a ‘ safe height ’ - anyone working off the ground is at risk of falling and being injured. Always consider the hierarchy of work, and ask yourself - Do we need to work at height ? Is there another way ? If there is no alternative then use this presentation as guide to help select the best method of access / protection.