Hierarchy of control for working at height
To achieve this managing work at height follows a hierarchy of controls the main principles of this are to avoid, prevent, arrest . The starting question for anyone working in construction should always be can the work be done safely from the ground? The answer to this question is often that it can not and working at height can not be eliminated altogether.
In summary, the hierarchy is explained below:-
- Avoid WAH (for example to clean windows use a high-reach brush to clean working from the ground)
- Prevent Falls (using collective measures scaffolds etc.)
- Minimise distance of the fall (collective before individual/personal erect scaffolds etc.)
- Minimise the Consequence of the fall (use fall arrest/fall restraint solutions)
- Train, Inform, and instruct (ensure competent employees only work at height and know how to check and use equipment safely)
To manage the hazards and risks associated with work at height in the construction industry, duty holders must assess the risks and implement control measures considering the practicality of implementing this hierarchy in their proposed solutions and mitigation measures from a starting point as high up the hierarchy of control as possible.
In relation to Construction(Design and Management) Regulations 2015 (CDM) which is applicable to all construction work whether it is notifiable to the Health and Safety Executive or not, basic principles are that the design of any aspect of construction work should seek to eliminate the requirement to work at height by firstly considering the design and designing out working at height altogether. Where this is not possible, only then should duty holders consider safe systems of work for working at height.
Fall restraints including PPE and safety netting should only be contemplated as a last resort if other safety equipment cannot be used. Therefore, collective measures (which are also referred to as passive measures) such as scaffolds, guard rails, and access towers should always be considered as the first measures when devising a safe system of work that protects everyone when working at height when they are in place.
In specifying personal fall arrest equipment, such equipment only minimises the consequence of a fall and is reliant on being attached. This introduces reliance on the behaviours of individuals to, correctly inspect, wear, and secure such equipment safely. Even with sufficient information, instruction and training provided by the employer, individuals do not always follow their training or safe systems of work for a variety of reasons e.g., taking shortcuts, programme time constraints, etc. which can result in a fall from height.
Working at height in the construction industry covers a wide spectrum of activities from basic work using a ladder to changing a light bulb (short-term duration) to undertaking complex works creating concrete floors for high-rise buildings to even more complex works involving work positioning and rope access methods in survey and maintenance of high-rise complex structures such as suspension bridges. Regardless of the degree of complexity, the approach to assessing risk and prevention of falls should be the same.
Often solutions to provide safe access/egress for working at height in construction require to be designed and have an engineered solution. They are what is classified as “temporary works” which can be described as parts of a construction project that are needed to enable the permanent works to be built. This is normally in relation to access/egress. Usually although not always, these are removed after use – e.g., access scaffolds, edge protection, excavation support/guard rails, falsework and formwork including access decks, etc.
Contractors should have temporary works procedures in place that follow the British Standard BS5975:2019, Code of Practice for temporary works procedures and the permissible stress design of falsework. These types of designs should aim to include the information necessary to erect, dismantle, and alter temporary structures safely, without the risk that facilitates working at height safely.
Other designs for such equipment are those published by manufacturers/suppliers and are known as proprietary products such as mobile access towers etc. When selecting any proprietary product, the duty holder should consider the guidance available from the supplier or service provider and ask themselves if the procedures shown can eliminate the risk throughout every stage of the process of erecting and dismantling the product in addition to how it will be used regarding a person falling from height.
Regardless of whether access solutions are bespoke or proprietary, it is a duty holder’s responsibility to ensure that they are of sufficient dimensions, sufficient strength, and rigidity for the purposes for which they are being used, and otherwise suitable. Also, they are placed so that they cannot be displaced. Regarding guard rails wherever they are required safe heights are:-
- The top guard-rail shall be at least 950 millimetres above the edge a person could fall from.
- The intermediate guard-rail shall not have any gap exceeding 470 millimetres.
While there are many scaffolding systems, mobile access towers available on the market in most instances do not offer a system of work that fully complies with Regulation 6.3 of the Work at Height Regulations 2005 therefore caution should also be given when selecting the individuals to erect such equipment. Duty holders should ensure that they only ask competent employees/suppliers to erect such equipment. Sensible product selection combined with product guidance/standards, design and training are vitally important to providing a safe system of work for working at height.
Whilst some consider training for employees utilising working at height solutions, awareness training is vitally important for others involved in construction work such as planners, supervisors, managers, and safety auditors. This facilitates the planning, selection, organisation, supervision and checking of the system of work for working at height and that it is being conducted correctly.
Employees should be trained through national schemes or similar alternative solutions to be able to prove compliance. Where relevant they should also undertake periodic medical examinations to ensure that they are medically fit to work at height in the construction industry.
Examples of various formal training industry competencies for working at height are detailed below:
- IPAF (International Powered Access Federation) for the use of mobile elevated working platforms (MEWPs)
- PASMA (Prefabricated, Access Suppliers’ and manufacturers’ association)
- CSCS (Construction Scaffold Competency Scheme) – for safe erection/dismantling and inspection of scaffolds from basic to advanced level.
- IRATA (Industrial Rope Access Trade Association) – for work positioning and rope access training
- FASET (Fall Arrest Safety Equipment Training) – for the use of nets etc.