Fall arrest systems

A great diversity of personal fall protection systems are used by workers who have to work at height to position the worker or to restrain his/her movements in order to prevent falls or to protect him/her in case of fall. A fall arrest system is used where there is a risk of free fall from height.

This article presents the main personal fall protection systems and their general construction, characteristics and role in use, with a focus on fall arrest systems. In addition, the European regulations and standards to be applied when these products are manufactured or used at the workplace are presented here.

Statistics prove that working at height is a dangerous working condition, whatever the height^[1][2][3][4]. The most common accidents are falls from height and the injuries can be caused by trauma and bone fractures to ruptures of internal organs, massive internal bleeding and, ultimately, to death.

If one wishes to prevent accidents involving falls from heights, priority must be given to having in place appropriate collective fall protection measures. When collective protection cannot be provided or the cost could be prohibitive, personal protective equipment (PPE) must be used, either to prevent the fall or to arrest the fall and to maintain the user in a safe position.

There is reliable scientific data from biomechanical research that the nature and severity of injuries depend on the value of deceleration and the forces developed in the body at the moment of a sudden cessation of the movement after a fall from height and of the duration to reach the peak acceleration. Even in the absence of an impact with stationary objects, extremely high forces are generated on the worker’s body at the moment of a sudden arrest of the movement. These forces can exceed 1,500 kg or 15 kN (kilo newton, unit of force) so that falling from a height of about 2 m can produce serious injuries^[5]. Peak decelerations of over 12 times the gravitational acceleration, i.e. 12G, at the moment of impact or fall cessation could also be dangerous for people, particularly to people with health problems.

In order to avoid injuries, personal protective equipment (PPE) should be designed to resist the maximum forces that could be developed during a fall, and the equipment should reduce these forces and the deceleration on the wearer to the kinds of values that are not dangerous. A deceleration of 12G is considered survivable if the individual is wearing a parachute harness, but the postures, physical fitness levels, harness attachment location, ’wearer comfort’ and other factors have influenced the advisability that 6G should be considered as a maximum for users of industrial harnesses. This means that for a medium body weight of 100 kg, the maximum arrest force is 6 kN according to European standardisation and maximum 8 kN according to American standardisation^[6]. Only certain components, or assembly of components, fulfil these conditions and can be used where there is the risk of falling from height.

PPE against falls from heights must also be adapted to the body of the wearer and to the workplace. It must be comfortable for the wearer during normal activity and in the case of a fall, at least, for a short time.

Analyses of the causes of falls from heights (Jarvis, 2009) show that there are five main reasons for high accident rates:

• Poor workplace design;

• collapse of access support;
• worker was required to work beyond the confines of the safe system;
• inadequate, poorly designed or absent edge protection;
• work environment restrictions are ignored because they are impracticable.

The collapse of access support can occur as a result of contact with abrasive materials or with cutting edges or as a result of environmental factors, such us temperature, cold, high humidity. The PPE should maintain its characteristics in any foreseeable environmental conditions for a sufficiently long period and any changes affecting their performances should be easily observed.

Definitions related to personal protective equipment against falls from height

Personal protective equipment (PPE) means any equipment designed to be worn or held by the worker to protect him/her against one or more hazards likely to endanger his safety and health at work, and any addition or accessory designed to meet this objective^[7]. The definition covers a single device, a unit constituted by several devices or appliances which have been integrally combined by the manufacturer, a protective device or appliance combined, separable or inseparable, with personal non-protective equipment or interchangeable PPE components which are essential to its satisfactory functioning and used exclusively for such equipment^[1].

In order to ensure protection against falls from height, different devices and components disposable on the market, at the points of sale can be assembled by the users in such a way to avoid the risk of injuries due to falls. These kinds of PPE components are: body holding devices (e.g. harnesses, thigh straps, belts) or accessories intended for attaching a person to a structure (lanyards, mobile fall arresters, karabiners, energy absorbers, connectors, certain types of anchor points), or dynamic mountaineering devices (e.g. ropes, slings, connectors rope clamps, chocks, rock anchors/pitons).

A personal fall protection system is an assembly of components intended to protect the user against falls from a height, constituted of:

• a body holding device – a full body harness, sitting harness, work positioning belt, rescue harness, rescue loop; and

• an attachment system, including an anchor device which can be connected to a reliable anchorage point.

The main types of personal fall protective systems and their roles are:

• restraint systems: prevent the user from reaching a zone where the risk of falling from height exists;

• work positioning systems: prevent a free fall while enabling the user to work at height under tension or in suspension;

• rope access systems: enable the user to gain access to and from the place of work in such a way that a free fall is prevented or arrested, by using a working line and a safety line, separately connected to reliable anchor points, it can be used for fixing the work position or for rescue;

• fall arrest systems: stop the falling and at the same time reduce the impact force exerted upon the user’s body;
• rescue systems: ensure that a person can rescue herself or rescue other persons in such a way that a free fall is prevented.

A fall arrest system is a personal fall protection system which prevents the user from colliding with the ground, structure, or any other obstacle during a free fall and limits the impact force on the body of the user during fall arrest^[8].

Work at height regulations regarding prevention of falls

European directives regarding workplace health and safety, including temporary work at a height, such as 89/655/EEC amended by 2001/45/EC, require that after a risk assessment, the employers must take technical measures to prevent falling from heights during access to work or at the workplace. They give priority to collective protection measures (solid cradles, scaffolding and platforms or safety nets) over personal protection measures. Particular provisions in this regulation are devoted to the use of rope access and positioning techniques. In contrast to other older national legislation requiring special protective measures starting from a height of more than 2 m, a new European directive (2001/45/EC^[9]) does not establish a limit any longer for the minimum distance from ground/floor that demands particular protective measures^[4]

The European directive regarding the use of PPE at the workplace establishes the main rules to be respected by the employee in order to ensure that the PPE is adequate and will protect the final user/employee^[1]. PPE must be provided free of charge to the employee. This directive recommends the use of harnesses (for work on scaffolding, assembly of prefabricated parts, work on masts) or ropes (for work in high crane cabs, work in high cabs of warehouse stacking and retrieval equipment, work in high sections of drilling towers, work in shafts and sewers).

Components of personal fall protective systems are PPE covered by the Directive 89/686/EEC as amended by Directives 93/68/EEC, 93/95/EEC and 96/58/EC, which specify the basic health and safety requirements and other conditions to be respected by the PPE introduced on the internal market or used in the European Union area. The manufacturer has entire responsibility for ensuring conformity of PPE with all provisions of the legislation.

The above regulations impose specific obligations either for the manufacturer, either for the employer/user, in order to ensure that the PPE used at the workplace, and in particular the fall arrest system, are safe and fulfil the protective function. Table 1 comprises a synthesis of these obligations^[2].

The data in Table 1 highlight the fact that the manufacturer must identify and declare the foreseeable conditions and limit the use and to provide sufficient information to ensure the correct use and maintenance of the equipment. The actual conditions at the workplace, established by the employer, must be as close as possible to those recommended by the manufacturer of the PPE and should never overstep the prescribed limits. In order to avoid errors, misuse or premature degradation of PPE, the employer and the workers must respect the indications given in the information file provided by the manufacturer(s) of all components of the personal fall protective system.

In an attempt to reducing the difficulties in choosing the most appropriate work equipment or PPE, especially for small and medium-sized enterprises and to help them both to improve the safety of their workers and to control their production costs, the European Commission has developed guidelines for implementing these directives through ‘best practices’ identified by a large number of European experts^[3][11].

Member States of European Communities, as well as other states or professional associations have developed specific regulation, guidelines for work at height in certain economic sectors^[12] or for PPE against falls from height^[13].

CE marking and personal fall protection systems

Personal protective equipment (PPE) against falls from height protect the user against a danger leading to fatal accidents and it is classified according the Directive 89/686/EEC as “PPE of complex design", commonly designated as “Category III PPE". This category of PPE must undergo two procedures of evaluation of its conformity at notified bodies: ‘EC type examination’, before placing a model of PPE on the market and ‘System for ensuring EC quality of production by means of monitoring’ or ‘EC quality control system for the final product’, during production. ‘Notified bodies’ are third-party, independent bodies appointed by Member States to carry out these procedures and notified to the European Commission. A list of the notified bodies, with their identification number and the specific tasks for which they have been designated is published by the Commission. The information file of the manufacturer shall comprise data about the applied procedures and the name and address of the notified body or bodies involved. Each personal protective equipment item against falls from heights must have the CE marking followed by four digits representing the number of the regulatory body controlling the production.

Some equipment for work at height is not considered as PPE as a result of analyses which revealed that its efficacy was not evident as covered by the definition of PPE^[11]. This group commonly known as “category 0" includes:

• anchor points forming an integral part of the structure or rock face, such as anchor points type A, C, D and E conform to EN 795:1996;

• equipment for accessing or leaving positions at height (winch seats, descenders not fitted with a built-in speed-regulating system, etc.)

• hammers, rope-climbing equipment and other similar equipment for climbing, rock climbing;

• support equipment (harnesses, etc.), designed and manufactured for use with parachutes, paragliders etc. and which cannot be used for other purposes.

Systems used in professional and private sports activities are not considered PPE^[4]. Equipment of category 0 shall not be subject to the procedures of certification at a notified body and shall not bear the European conformity marking CE.

European harmonized standards related to personal fall protection systems

Nowadays, there are almost 40 European harmonized standards, covering:

• general requirements for personal protective systems and for instructions for use, maintenance, periodic examination, repair, marking and packaging (EN 365: 2004);

• specific requirements for components: belts (EN 358: 1999) and full body harnesses (EN 361: 2002), connectors (EN 362: 2004), lanyards, energy absorbers (EN 355: 2002), descending devices (EN 341: 1992+ EN 341:1992/A1: 1996), retractable type fall arresters (EN 360: 2002), guided type fall arresters including a flexible anchor line (EN 353-2: 2002), fall arrest systems^[4], accessory cord for mountaineering equipment (EN 564:2006), anchor devices (EN 795:1996/ A1: 2000), sit harnesses (EN 813:2008); etc;

• testing methods (EN 364: 1992).

European harmonized standards specify requirements regarding design, performances (e.g. static resistance, dynamic resistance or dynamic performance), marking and content of information file of the manufacturer. The values of static strength established in the standards for each component are established multiplying the limit values considered to ensure the safety of the wearer, of 6 kN, with a factor determined based on materials, the application and the historical industry practice^[14].

Conformity of a PPE with a published European harmonized standard gives the presumption of conformity with the basic health and safety requirements of directive 89/686/EEC, covered by the standard. It also means that all the similar products on the market meet the same requirements and ensure the same high level of protection; this facilitates that the assembly built by the user of the system will be adequate for the workplace, although the employers still have to make the necessary subsequent evaluations with regard to the dimensional compatibility of different components, adapt of the entire system to the workplace and the worker.

The list of European harmonized standards in application of directive 89/686/EEC is periodically updated and published^[15].

Fall arrest systems, components and main characteristics

A fall arrest system includes:

• a suitable body holding device, that is a full body harness;

• an energy absorbing element: energy absorber, retractable type fall arrester, guided type fall arrester including a rigid anchor line; guided type fall arrester including a flexible support;

• an anchor line;

• an anchor point;

• connectors/karabiners/hooks;

• lanyards.

The components, except the anchor point, can be separable or inseparably connected. A fall arrest system does not prevent the fall, allowing the user to reach a zone where free fall risk exists, but should a free fall occur, the system stops it, limiting the length of fall to prevent collision with the ground, with the structure from where the worker is falling or other obstacles and it maintains the user in an acceptable ergonomic position until rescue.

Each type of system is intended to ensure that the impact forces on the body of the user during the arrest of a free fall are restricted to the maximum value accepted as non-dangerous, i.e. 6 KN in Europe.

Each type of system is characterised by an “arrest distance", established during the CE type-examination. This value forms the base from which to calculate the minimum ‘free space‘ or ‘clearance’ that is necessary under the legs of the worker to avoid a collision. The ‘clearance’ of a fall arrest system is calculated by adding 1 m to the arrest distance and it is indicated in the information file of the manufacturer. The decision to use a particular type of fall arrest system needs to take into account the clearance of the disposable energy absorber in balance with the actual clearance at the workplace.

Components may be used in various types of personal fall protective systems, as long as they are suitable for the specific purpose of the system. There are several possible combinations of elements, each one being specific for a particular purpose, or alternatively for particular configurations in the workplace: work on horizontal or inclined surfaces or on towers, anchor points above or under the worker, existence of a free space under the wearer.

Factors in assembling the components of a fall arrest system

Most of the manufacturers deliver components of PPE against falls from height that can be assembled in different fall arrest systems. They provide recommendations regarding the compatibility of their products with other components. In addition, the employer of the workplace can assemble different components to obtain an adequate fall arrest system, starting from components delivered by one or more manufacturers. In both cases, it is the responsibility of the employer of the workplace to check the adequacy of the system to the activity to be performed and to the conditions of workplace.

When combining components into a fall arrest system, the following aspects need to be taken into consideration:

• suitability of components for the intended use of the fall arrest system, taking into account all the different phases of use (e.g. access to work);

• the characteristics of the workplace (e.g. a sloping floor in a workplace, location of anchor device, the need for free movement over a long distance, other objects in the space where a fall could occur that could impact with the body). The actual free height under the worker shall be greater or at least equal to the minimum necessary clearance indicated by the manufacturer of the absorber or fall arrester;

• the intended user (e.g. level of competence, experience), in order to establish the needed training

• compatibility of components (e.g. interaction between anchoring device and other components);
• ergonomic considerations (e.g. choosing the correct harness and attachment elements to minimise discomfort and stress to the body);

• the information supplied for all components by their manufacturers;

• the need to facilitate safe and effective rescue operations (e.g. to prevent trauma caused by remaining suspended at height, taking into account that after a fall, it takes from 6 to 20 minutes of inert suspension for a healthy person to lose consciousness);

• characteristics of the anchorage (e.g. location, strength, form).

Experts consider that there are ten criteria that every executive or worker must apply to the personal fall protective systems when selecting the equipment necessary to complete their tasks safely and in compliance with the current legislation^[16]. This implies that in addition to the above criteria traceability and security of the fall arrest system, taking into account the previous exposure to shocks or aggressive agents or the natural aging.

Types of fall arrest systems and main components

Fall arrest system incorporating a lanyard and energy absorber

It is assembled out of:^[4]

• full body harness (B in figure 2);

• lanyard (C in figure 2);

• energy absorber (D in figure 2);

• anchor point – (A in figure 2);

• connectors - optionally, to join the other components.

This type of fall arrest system is used when there is an anchor point above the user and a sufficient high clearance. The arrest distance, H, should be H < 2 L_t + 1,75 m, where L_t is the overall length of the energy absorber and lanyard. Whatever energy absorber is used, L_t has in any case has to have a value of more than 0,5 m, the arrest distance is over 3 m and the necessary clearance is usually over 4 m.

Fall arrest system incorporating a lanyard and energy absorber on a horizontal line

It is assembled out of:^[4]

• full body harness (B in figure 3);

• lanyard (C in figure 3);

• energy absorber (D in figure 3);

• mobile anchor point located on the flexible horizontal anchor lines (A in figure 3);

• connectors.

This kind of fall arrest system can be used on platforms without barriers, when it is not possible to have a point of anchorage situated above. The advantage is that such a system allows free movements along the horizontal anchor line, but a limited free movement in front or behind this point, on a distance equal to the total length of the absorber and lanyard.

Fall arrest system incorporating a retractable type fall arrester

• a full body harness (B in figure 4);

• a retractable lanyard – element of retractable type fall arrester (C in figure 2);

• a retractable type fall arrester (D in figure 2);

• an anchor point (A in figure 4);

• connectors.

The retractable type fall arrester is a cable or webbing device, which self-retracts inside a housing unit to ensure that the cable or webbing remains taut at all times. It is available in a variety of lengths up to 60m. With a built-in shock absorber, it arrests the falling worker within distances of less than 1m. Extension of the unit is not allowed without the manufacturer’s approval, and the attachment of shock absorbing lanyards is strictly prohibited. This type of a fall arrest system should be used only in the vertical plane, with the anchor point being located above the head. Misuse in ways that ignore above specifications or the use ‘over edge’ can lead to serious, even fatal accidents ^[17]. The conditions of use stipulated in the instructions manual provided by the manufacturers shall be carefully observed.

Fall arrest system incorporating a guided type fall arrester including a flexible anchor line

It is assembled out of:ref name="EN 363: 2008"/>

• an anchor point (A in figure 5);

• a full body harness (B in figure 5);

• a lanyard (C in figure 5);

• a guided type fall arrester (D in figure 5);

• a flexible anchor line (E in figure 5);

• connectors.

The flexible anchor line is a lanyard or a wire cable fixed at an anchor point above the head of the worker and is easily tensioned downside. These devices are installed temporarily and should be used in conjunction with a harness with frontal or dorsal attachment elements. Depending on the length of the lanyard, it allows a certain free lateral movement, but the arrest distance, i.e. the clearance increases with the length of the lanyard.

Fall arrest system incorporating a guided type fall arrester including a rigid anchor line

It is assembled out of:^[4]

• a full body harness (B in figure 6);

• a lanyard (C in figure 6);

• a guided type fall arrester (D in figure 6)

• a rigid anchor line (A in figure 6);

• connectors.

These devices are permanently installed, usually on very high radio antennas, towers or chimneys. The anchor line is an anchor rail fixed directly to the tower, the edge of a ladder or a wire rope tensioned fixed on a structure, in such a way to limit the lateral movements. The system should be used in conjunction with a front attachment harness directly to a connector with/without lanyard. It allows little free lateral movements of the wearer and is generally characterised by small values of the arrest distance.

Full body harnesses for fall arrest systems

A full body harness is formed of straps made of webbing, buckles, attachment elements and other elements adequately positioned and adjusted on the potential user’s body. It shall have at least a sub-pelvic strap and shoulder straps; it may include thigh strap, chest strap and/or a positioning belt with or without a back support. In order to maintain the body in a safe position after a fall, the attachment elements designed for using in a fall arrest system shall be above the gravity centre of the body, respectively on the chest/stern, on the back or on the shoulders. It can also be incorporated into the clothing.

The full body harness should be adjustable on the user’s body and shall not pose a risk of releasing the body through rupture or elongation. In order that any signs of wear and tear that could affect the mechanical resistance capacity be readily observed, the threads shall have a colour different to the other textile parts.

EN 365:2004^[18] (Personal protective equipment against falls from a height) presents general requirements for instructions for use, maintenance, periodic examination, repair, marking and packaging gives general requirements for periodic inspection, instructions for use and marking of PPE against falls from a height. It is not sufficient for employers to provide employees with a fall arrest system.. They must ensure that they have complete procedures in place for selecting an appropriate system, training employees in its use and maintenance, regular inspection of elements of the system etc. For example, EN 365 states that components should be examined ‘at least twelve-monthly’, although this should be regarded as a maximum period between inspections with the frequency related to the frequency of use of the equipment. As well as any harness this should cover lanyards, connecting devices and all other components. Inspection may include regular (daily) simple examinations as well as more lengthy inspection by a suitably competent person. Guidance on such inspections is readily available^[19]. It includes interim and detailed inspections as as well as record keeping that should cover details both of use and of all inspections.

Employees’ training on maintenance of fall arrest systems

European regulations for health and safety at workplace stipulate that a worker should be provided with pre-selected equipment suitable for his/her task by his/her employer and should be trained to use it, including by practical demonstrations.

Users must know the way of putting and taking off the PPE, its characteristics, its limits, as well as what checks are to be made before starting the work and other inspection, following the data included in the information file supplied by the manufacturer for each PPE.

Those employees working at height must be selected not only on the basis of professional skills to do the work in question (electrical wiring, building, etc), but also based on appropriate training about the use of personal fall protection systems. The employee’s physical capacity and specific skills must be observed especially when using the access systems^[20]. In most countries, employees using rope access systems must have undergone special theoretical and practical training, as well as having a 'health permit', that they are healthy and able to perform activities at height.

A periodical inspection should be made at least once per year. The inspection and/or testing for periodic examination should be made by competent personnel, designated at the entire organisation level or by a representative of the manufacturer, having knowledge of the risk factors for PPE and the tests or signs indicating the loss of safety characteristics due to usage or natural aging^[21].

Each component should be accompanied throughout the lifetime of the product by a record, identifying the product and the date of purchase and describing the history of periodic examinations and repairs and the next due date for periodic examination.