Construction

A lot of people get hurt and killed on construction sites every year. The reality is that there are few hazards that only occur on construction sites but there are often more of them present at any time and keeping control can be difficult.  Also, the way buildings and other structures are designed and constructed needs careful consideration to ensure they can be built, used, maintained and even demolished safely.

1.1                      The design and construction process

1.1.1                       Parties involved in construction

There are a number of parties involved in construction.  All have a part to play in safety, and this requires them to cooperate.  They include

  • The client – the person who has commissioned the work;
  • Designers – people who influence what is built;
  • Principle contractor;
  • Sub-contractors.

Because of the number of parties, someone will typically need to take responsibility for co-ordinating the construction.

1.1.2                       Designers

Part of the problem with the construction industry is that safety is not always adequately considered when buildings and other structures are designed.  This is a fundamental flaw that can result in injury to construction workers, and have an impact on future users and maintainers.  To avoid this it is important that building designers

  • Eliminate hazards where possible;
  • Reduce risks from those hazards that cannot be eliminated (e.g. specify designs to reduce the need/frequency for hazardous tasks during construction and subsequent use and maintenance);
  • Provide information on any significant residual risks (e.g. if a set sequence of assembly or demolition is required to maintain structural stability).

In order to achieve the above a competent designer will need knowledge and experience of the construction process.  In this context designers include anyone who specifies what is built or how it is built including architects, consulting engineers, quantity surveyors, building service engineers, temporary works engineers.

1.1.3                       Considerations at the pre-tender stage of a project

Making provision for safety can be expensive, and if not properly budgeted for it may not happen.  Because of the competitive nature of tendering for construction work, it is important that principle contractors have full information about hazards and risks at the time of preparing their bid.  That way they can prepare a safe schedule of work and therefore specify a realistic price.

1.1.4                       Health and safety during construction

Construction activity is inherently hazardous and so good health and safety planning is essential.  Plans should be developed that cover:

  • The arrangements for the management of health and safety of the construction work;
  • The monitoring systems for checking that the health and safety plan is being followed;
  • Health and safety risks to those at work, and others, arising from the construction work, and from other work in premises where construction work may be carried out.

1.2                      What happens on construction sites?

People get hurt on construction sites because:

  • They fall off things;
  • They fall into things (e.g. holes);
  • They trip over things;
  • Things are dropped on them;
  • They are squashed by moving equipment and vehicles;
  • They are exposed to hazardous substances (especially asbestos, dust and solvents in adhesives and paints);
  • They come into contact with electricity;
  • They get hurt during manual handling

The challenge is that because of the nature of activity, the situation is very fluid and changes all the time.  Also, there can be many parties involved in hazardous work at any time.  This is why managing safety on construction sites is often a challenge.

1.3                      Work at height

People falling from height are at risk of injury.  Even falls from low heights can cause serious injury, although the distance fallen is clearly a factor in the actual consequences.

1.3.1                       Planning work at height

Before carrying out work at height the first question must always be whether it can be avoided.  If not, it is important that the work is planned properly and the risks assessed.  Good organisation and competent people are required.

Planning the work should include the following:

  • Selection of the correct method of access (e.g. ladder, scaffold tower, scaffolding, mobile elevating work platform (MEWP));
  • Measures to prevent falls (e.g. guardrails);
  • Mitigation that reduces distance fallen or impact for anyone who may fall (e.g. nets and airbags);
  • Personal mitigation that an individual can use (e.g. line and harness or fall arrestor).

1.3.2                       Using ladders when working at height

Some people mistakenly believe that ladders and step-ladders are banned under health and safety regulations.  This is not the case.  However, it is important to recognise that people die every year falling from ladders, and so their use needs to be controlled.

  • Ladders and step-ladders can be used if after assessing the risks the use of more suitable work equipment is not justified because of the low risk and short duration;
  • Short duration is taken to be less than 30 minutes;
  • They should only be used for light work (less than 10kg);
  • Ladders can also be used for low risk work where there are features on the site that mean a ladder must be used.

Precautions for using ladders include:

  • Ladder angle should be no more than 75o (1 unit of distance out for every 4 units up);
  • Always grip the ladder when climbing;
  • Do not overreach;
  • Do not work off the top three rungs – this provides a handhold;
  • Carry out daily pre-use checks;
  • Ensure there is space to fully open the ladder;
  • Use any locking devices;
  • Only use a ladder on firm and level ground;
  • Make sure floors are clean and not slippery.

Additional precautions for using step ladders include:

  • Do not work off the top two steps unless you have a safe handhold on the steps;
  • Avoid side-on working;
  • Do not overreach.

Reference – ‘Top tips for ladder and stepladder safety’ available free at http://www.hse.gov.uk/pubns/indg455.pdf

1.3.3                       Using mobile towers when working from height

Mobile access towers come in sections that are fitted together to create a platform for working at height. They can be very useful, avoiding the need for scaffolding, but have their limitations. They are usually quite light-weight, and so prone to toppling over. Also, they may not be particularly strong.

Manufacturers of towers have a duty to provide the information necessary to use them safely.  This includes how they fit together, maximum height, and use of stabilisers.  Clearly towers should only be used in accordance with these instructions.

Other points to note include:

  • Only erect on firm, level ground;
  • Beware of overhead cables;
  • Protect against vehicle impact;
  • Do not put on blocks or bricks;
  • Make sure casters (wheels) are locked when the tower is being built or is in use;
  • Do not attach any sheeting, unless the tower is designed for that use (wind can blow tower over);
  • Only hoist material in accordance with the tower’s design;
  • Ensure there is a safe way to get to the top. Some towers are designed to be climbed, others have ladders built in;
  • Never use a tower as a support for ladders, trestles or other access equipment;
  • Do not use in weather conditions likely to make the tower unstable (wind, rain affecting ground);
  • Beware of overhead cables when moving the tower – reduce height to below 4 metres;
  • Do not use vehicles to move towers.

1.3.4                       Using scaffolding when working from height

Scaffolding provides a means of working at height.  However, erecting scaffolding can be hazardous in its own right, and the safety of the people using it depends on how it is designed, erected and maintained.  There are codes of practice that cover scaffolding, including use of fall arrest equipment whilst it is being erected or altered.

Key requirements for safe use of scaffolding include:

  • It must only be erected or modified by competent people;
  • It must be designed for the intended use by competent people;
  • Handling various components (poles etc.) can cause hazard due to weight, dropped items or knocking people over;
  • Scaffolds must be inspected by a competent person before first use, after modification, after an event that may have affected its integrity (e.g. adverse weather) and at 7 day intervals;
  • Scaffolding must be erected on firm, level ground or foundations (beware of hidden voids, drains etc.);
  • Beware of overhead cables;
  • Protect against vehicle impact;
  • If intended to take loads, it must be designed and constructed accordingly;
  • If intended to be sheeted, it must be designed and constructed to withstand wind load;
  • Working platforms must be properly supported and large enough for people to work (minimum width 600mm);
  • Guardrails should be provided at working platforms to prevent people falling (approximately 1m high, with intermediate guard rails provided so gaps are less than 470mm);
  • Toe boards should be provided on working platforms to prevent materials falling (minimum height 150 mm);
  • Safe ladder or other access must be provided;
  • Arrangements need to be made for raising and lowering of materials;
  • Make sure ends and other parts are easy to see so people do not walk into them;
  • Mark incomplete sections so that they are not used;
  • Prevent unauthorised access by removing ladders or covering rungs.

For stability, the scaffold should usually be tied in to the structure being built or worked on.  There are different types of tie:

  • Through tie – a scaffold pole is extended through an opening (e.g. window) and then arrangements are made so that pressure is applied to the wall opposite to the scaffolding (i.e. on the inside of the building if the scaffold in on the outside);
  • Reveal tie – again in an opening, but a pole is wedged horizontally into the opening and screw devices used to tighten the gap so that friction is used stop the pole moving;
  • Box tie – attached around a pillar or similar structure;
  • Eye bolts – screwed into the wall onto which scaffold is attached;
  • Putlog – poles with flattened ends which are inserted into gaps between brick courses.

Where ties are not possible, angled supports can be used to support the scaffold.

Reference – ‘Scaffold checklist’ available free at http://www.hse.gov.uk/construction/safetytopics/scaffoldinginfo.htm

1.3.5                       Mobile Elevated Work Platforms (MEWP)

The term MEWP applies to a number of different types of equipment including vehicle mounted articulated and telescopic booms, self-propelled articulated and telescopic booms, trailer mounted articulated and telescopic booms and scissor lifts.  Some of these are commonly known as ‘cherry pickers.’

Potential problems with MEWPs include:

  • Collapsing;
  • Overturning;
  • Persons being thrown from the carrier during manoeuvres;
  • Carrier being trapped against fixed structures;
  • People being crushed by them.

The risk of falling from a MEWP is increased by a sudden movement caused by an impact, ground movement, or failure of a stability critical part of the MEWP.  Some form of lanyard or other protection can prevent these events causing injury.

Issues to consider are really a combination of access to height, vehicle use, lifting operation and use of work equipment.  In particular;

  • Stability and slope of ground;
  • Hidden underground voids;
  • Overhead cables;
  • Vehicle collision;
  • Engine acting as ignition source;
  • Engine fumes creating a hazard (e.g. confined space);
  • Formal inspection of equipment;
  • User checks.

The correct equipment needs to be selected and operators must be competent.

Reference – ‘The selection and management of mobile elevating work platforms’ available free at http://www.hse.gov.uk/pubns/geis6.htm

1.3.6                       Rope access

Rope access is a method of working at height, developed from techniques used in climbing and caving.  Typical jobs carried out using rope access include inspection and testing, maintenance, painting, cleaning structures and windows.  It can be hazardous, so people are have to be competent and apply rigorous safety precautions, including:

  • Use of two attachments, each having an independent anchorage point;
  • When supported by ropes, fail-safe descent mechanism must be used;
  • All secondary tools and equipment (e.g. drills, sealant, etc.) must be attached by lanyards to worker’s harness;
  • A minimum of two technicians are required for any job;
  • Teams must be trained in rescue procedures;
  • All equipment must be regularly inspected and maintained.

Further information is available from the International Rope Access Trade Associate (IRATA) at http://www.irata.org

1.3.7                       Work at Height regulations 2005

The Work at Height Regulations 2005 apply to all work at height where there is a risk of a fall liable to cause personal injury.  There is no minimum height specified (in the past people have referred to the 2 metre rule, but this no longer applies).

Duties are placed on employers, the self-employed, and any person that controls the work of others (for example facilities managers or building owners who may contract others to work at height).  They include:

  • Avoid work at height wherever possible;
  • Use work equipment or other measures to prevent falls where working at height cannot be avoided;
  • Use work equipment or other measures to minimise the distance and consequences of a fall should one occur where the risk of fall cannot be avoided.

Specific issues covered by the regulations include:

  • All work at height must be properly planned and organised;
  • Planning for work at height must take account of weather conditions that could endanger health and safety;
  • Those involved in work at height must be trained and competent;
  • The place where work at height is done must be safe;
  • Equipment for work at height must be appropriately inspected;
  • The risks from fragile surfaces must be properly controlled;
  • The risks from falling objects must be properly controlled.

The regulations were amended in April 2007 to apply to those who work at height providing instruction or leadership to one or more people engaged in caving or climbing by way of sport, recreation, team building or similar activities in Great Britain.

Reference – ‘The Work at Height Regulations 2005 – a brief guide’ available free at www.hse.gov.uk/pubns/indg401.pdf

1.4                      Other construction related hazards

1.4.1                       Excavations

Excavations create a number of hazards closely related to working at height.  In particular people can fall into the excavation and things can be dropped on people who are in the hole.  There is no specific depth at which an excavation is considered to be dangerous, remembering that someone bending over or kneeling down in a shallow hole could be seriously hurt if it collapses.

Also, excavations can become confined spaces, there is the potential for sides to cave in and for contact to be made with underground hazards including buried services and contaminated soil.

Precautions to stop excavations caving in include angling the sides instead of making them vertical, making sure spoil from digging the excavation is not left at the side and providing support using timber, sheeting or propriety systems.

The potential for buried services should be identified before starting the excavation.  Where this risk is not zero precautions such as detectors/locators and digging of test trenches should be used.

A competent person must inspect excavations:

  • At the start of each shift before work begins;
  • After any event likely to have affected the strength or stability of the excavation;
  • After any accidental fall of rock, earth or other material.

A written report should be made after most inspections.

Of course there are also hazards associated with the method used to create the excavation.  Doing it by hand creates manual handling issues whilst alternative methods usually involve the use of vehicles.

1.4.2                       Confined space entry

A confined space is any space of an enclosed nature where there is a risk of death or serious injury from hazardous substances or dangerous conditions.  They include storage tanks, silos and vessels, enclosed drains and sewers, open-topped chambers, ductwork, poorly ventilated rooms and excavations.

Potential hazards include lack of oxygen, hazardous substances either from the previous contents of the space or the work being carried out (e.g. fumes), flammable atmospheres and hot working conditions.  Also, it must be recognised that rescuing someone from a confined space can be difficult due to poor access.  Confined space entry must be carefully planned and controlled.

Factors to consider when planning confined space entry include:

  • Is it necessary?
  • Are the people suitable for the task (competence and health)?
  • Isolating the space from all potential sources of hazard;
  • Cleaning the space;
  • Ensuring a large enough entry;
  • Providing ventilation;
  • Testing air quality;
  • Provision of special tools;
  • Lighting;
  • Use of breathing apparatus if there is a risk of the air becoming unbreathable (but it must not be used instead of isolation, cleaning etc.);
  • Emergency plan;
  • Rescue equipment;

The Confined Spaces Regulations 1997 apply.

Reference – ‘Safe work in confined spaces’ available free at http://www.hse.gov.uk/pubns/indg258.pdf

Reference – Approved Code of Practice L101 ‘Safe work in confined spaces’ available free at http://www.hse.gov.uk/pubns/priced/l101.pdf

1.4.3                       Work on or near water

Whenever someone is working near water or on water (sea, river, lake, pond) the risk of drowning must be considered.  Obviously it is most important that the likelihood of them falling in the water is minimised by providing barriers, working platforms, harness and lines etc.  However, where the risk of falling into water cannot be eliminated it is important to consider the provision of buoyancy aids and rescue plans.  Cheap and simple buoyancy aids tend to be bulky, and so are generally not suitable for anyone doing any work.  More practical buoyancy aids are likely to have a self-inflating mechanism, and it is essential that these are properly maintained and checked before use.  It is also important that people know how to use them.

Drowning is not the only hazard of falling into water.  Hypothermia can set in if someone is in cold water for some time (within 30 minutes).  Also, there are some animal borne diseases that are commonly found near water (e.g. leptospirosis causing Weils disease).

Reference – ‘Personal buoyancy equipment on inland and inshore waters’ available free at http://www.hse.gov.uk/pubns/ais1.pdf

1.5                      Construction Design and Management 2007 Regulations (CDM 2007)

CDM regulations apply to most common building, civil engineering and engineering construction work.  They require clients of construction work to make reasonable arrangements for managing projects (including the allocation of sufficient time and other resources) so that:

  1. Risks to health and safety are managed by applying general principles of prevention,
  2. The right people and organisations are appointed at the right time;
  3. Everyone has the information, instruction, training and supervision they need to carry out their jobs in a way that secure s health and safety
  4. Dutyholders cooperate and communicate with each other and co-ordinate their work
  5. Workers are consulted and engaged with to promote and develop effective measures to secure health, safety and welfare

The regulations identify the following duty holders and specify their role and main duties:

  • Clients;
  • Domestic clients (in the scope of the regulations but duties are normally transferred to the contractor to principal contractor);
  • Designers;
  • Principle designers;
  • Principal contactors;
  • Contractors;

Appointments need to be made in a timely manner so that there is time to develop suitable health and safety plans before construction begins.  Everyone involved in the project must seek the co-operation of, and co-operate with others working on the project.  Also, any person working under the control of another person has to report anything they are aware that is likely to endanger the health or safety of themselves or others.

Every person involved in design, planning and preparation of a project must take account of the general principles of prevention of accidents and ill health.

For the purposes of these Regulations, a project is notifiable to the Health and Safety Executive if it is is scheduled to last longer than 30 working days and have more than 20 workers working simultaneously at any point in the project; or exceed 500 person days.

A construction phase plan must be developed during the pre-construction phase and before setting up the construction site.  It must set out health and safety arrangements and site rules.

Where a project involves more than one contractor a health and safety file must also be prepared containing relavant information about the project.  It should include:

  • A brief description of the work carried out;
  • Any hazards that have not been eliminated through the design and
  • Construction processes, and how they have been addressed (eg surveys or other information concerning asbestos or contaminated land);
  • Key structural principles (eg bracing, sources of substantial stored energy including pre- or post-tensioned members) and safe working loads for floors and roofs;
  • Hazardous materials used (eg lead paints and special coatings);
  • Information regarding the removal or dismantling of installed plant and equipment (eg any special arrangements for lifting such equipment);
  • Health and safety information about equipment provided for cleaning or maintaining the structure;
  • The nature, location and markings of significant services, including underground cables; gas supply equipment; fire-fighting services etc;
  • Information and as-built drawings of the building, its plant and equipment (eg the means of safe access to and from service voids and fire doors).

The client must be given the safety file at the end of the project and take reasonable steps to ensure that it is kept available for inspection by those considering future construction work.

Reference – The regulations are available free at http://www.legislation.gov.uk/uksi/2015/51/pdfs/uksi_20150051_en.pdf

Reference – ‘Managing health and safety in construction’ available free at http://www.hse.gov.uk/pUbns/priced/l153.pdf

1.6                      Demolition

Demolition is essentially the opposite of construction, and similar approaches are required to manage the risks.  Specific issues to be aware of include:

  • Exposure of people to hazardous materials within the building or structure being demolished (e.g. asbestos);
  • Unpredictability of where material will fall – requiring adequate exclusion zones;
  • Potential to impact on members of the public;
  • Hazards from the method of demolition used (especially if using explosives).

As with construction, good planning is essential.  The CDM regulations apply to demolition.