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Having been asked if I could provide an article on height safety again this year, I have decided to focus on two areas of activity: improving safety in the use of portable leaning ladders and the use of restraint systems. The first is a high risk activity and the second often misunderstood.
By way of introduction, after almost 20 years in height safety, having been involved in design, installation, product sales, product and system maintenance through to training and accident investigation consultancy, I’m currently in the process of embracing retirement from the day to day activities of business. I have considered what pearl of wisdom I might impart to those involved in height safety by way of occupation, or as a by product of some other activity. It is this: ‘Keep it simple’.
It is easy to overcomplicate systems of work and in doing so expose people to additional risk. The more complicated and involved a procedure is, the more likely it will either not be used or will be used incorrectly.
When setting out to improve the safety of ladder users for aerial and satellite installation, it was with a background of underlying accidents, some minor, but some fatal. At the forefront of this work has been a small team of people, including HSE, CAI (Confederation of Aerial Industries) and consultants from the world of height safety, myself included.
The use of portable leaning ladders is widespread and often the preferred means of access for a significant number of trades.
Over the last eight years or so, significant work has been carried out to ensure that there is a simple, uncomplicated, safe and acceptable method of securing ladders and improving stability, to enable a fall protection system to be used. Often users are required to work alone, such as installers of television and satellite equipment. It is therefore vital to ensure a system that enables self-rescue in the vast majority of circumstances.
With the rush towards the 2012 deadline for digital switchover and the subsequent swelling in the number of aerial and satellite installation engineers, who are required to provide the aforementioned switchover, the need to improve safety has been pressing. Often engineers with many years of experience in installing aerials and satellite dishes from portable leaning ladders have had little understanding of height safety or the equipment used to provide it.
With this in mind, keeping things simple has made the change from little or no fall protection easier to accept and less complicated to deal with.
So successful has the system of work been, that it has been introduced to a much wider range of ladder users, from council housing maintenance, security systems engineers, electricity engineers, construction trades through to cavity wall installers.
With a great deal of hard work and dedication there has been nothing short of a revolution in the way in which this industry works when using portable leaning ladders, leading to an industry ‘Best Practice’ standard and a ‘Common Accord’ agreement, supported by HSE, a process I have been pleased to be involved with.
With any departure from standard practice, a great deal of testing has been carried out over many years, some to satisfy clients, some to satisfy HSE, but mostly to satisfy our own desire to ensure that the systems and equipment provided work well and provide safety for operatives.
With no resting on laurels, recent additional testing has been carried out to define the parameters of safety for other industries requiring additional flexibility.
These tests carried out by CSS Worksafe included:
Ladder safety system testing
1. Stability 2. Drop Testing 3. Repetitive Strain Testing 4. Axial Load Testing of Ladder Tie Bolts
1. References
• Work at Height Regulations 2005 • HSE OC 200/30: Safe Use of Ladders & Stepladders • BS8437: Code of Practice for the Selection, Use & Maintenance of Personal Fall Protection Systems for Use in the Workplace • HSE Research Report 205: Evaluating the Performance and Effectiveness of Ladder Stability Devices. (The Loughborough Report) • BS EN 364: Test Methods
2. Stability
HSE Research Report 205 identifies four classes of instability: • Base Slip • Top-Slip • Flip • Loss of Top Contact
Base Slip
A triple extension ladder extended to a height of 7m was secured using a tensioned, endless ratchet strap and eyebolt, and a force applied in the direction illustrated in figure 1 using a winch. A transducer capable of converting a measure of force into an electrical signal was connected to a load measuring system, which was in turn connected to the winch. A load of 175+kg was applied without any significant movement of the base of the ladder. Top Slip
A triple extension ladder extended to a height of 7m was secured using a tensioned, endless ratchet strap and eyebolt/s, and a force applied in the direction illustrated in figures 2, 3 & 4 using a winch and pulley system.
A transducer capable of converting a measure of force into an electrical signal was connected to a load measuring system, which was in turn connected to the winch.
Single Anchor Point: a load of 107kg was applied before any top slip of the ladder was observed. Two Anchor Points with ladder positioned centrally: a load of 75kg was applied before any top slip of the ladder was observed. Two Anchor Points with ladder positioned at extreme: a load of 50kg was applied before any top slip of the ladder was observed.
Loss of top contact
A triple extension ladder extended to a height of 7m was secured using a tensioned, endless ratchet strap and eyebolt, and a force applied in the direction illustrated in figure 5 using a winch. A transducer capable of converting a measure of force into an electrical signal was connected to a load measuring system, which was in turn connected to the winch.
A load of 140kgs was applied before the ladder feet lost contact with wall. The ladder did not fail and remained stable.
Flip
Flip was not tested. It was felt that resistance to flip would be at least as high as resistance to loss of top contact, which provided a very acceptable measure of safety.
Drop testing
A number of drop tests have been carried out both at CSS Worksafe and at UK Notified Body SATRA. The relevant Technical Services Reports from SATRA are available on request.
REF: SPC0156106/0738/NW
The test was designed to measure forces on the tensioned ratchet straps in the event of a fall and to test the effectiveness of the strapping configuration in the event of a fall to the side of the ladder. Three dynamic performance tests were carried out using a 100kg articulated dummy, wearing a 2-point harness. The dummy was attached via the front d-ring to a SKR type rope grab device that was in turn connected to an 11mm EN 1891 rope and Manuchroche connector and positioned to face the ladder. The ladder was secured via a tensioned ratchet strap to two anchors, forming a triangle. The distance between the anchors was 2.6m, the total width of the tower. The ladder was positioned horizontally offset from the centre of the tower.
Test 1: Factor 2 fall, dummy central to ladder.
Result = Dummy arrested and held. Ladder remained in place. Peak force recorded at tensioned strop = 1.2kN (initial tension in ratchet strap).
Test 2: Factor 2 fall, dummy offset to ‘outer’ side of ladder to ensure a fall from the side of the ladder.
Result = Dummy arrested and held. Ladder remained in place. Peak force recorded at tensioned strop = 1.2kN (initial tension in ratchet strap).
Test 3: Factor 2 fall, dummy offset to ‘inner’ side of ladder to ensure a fall from the side of the ladder.
Result = Dummy arrested and held. Ladder remained in place. Peak force recorded at tensioned strop = 1.2kN (initial tension in ratchet strap).
REF: SPC0180170/0946
The test was designed to measure forces generated by a heavy operative in the event of a fall and to test the effectiveness of the SKR Rope Grab Device to arrest such a fall.
A dynamic performance test was carried out using a 100kg articulated dummy wearing a 2-point harness with an additional 36kg of mass attached. The dummy was attached via the front d-ring to a SKR type rope grab device that was in turn connected to an 11mm EN 1891 rope and Manuchroche connector and positioned to face the ladder. The ladder was secured via a tensioned ratchet strap to a single anchor.
Result = 136kg articulated dummy arrested by SKR rope grab device. Peak force recorded at harnessattachment = 2.1kN.
REF: SPC01618/0623/PJD/NW
The test was designed to measure forces generated by a 100kg operative in the event of a fall and to test the effectiveness of the SKR Rope Grab Device to arrest such a fall.
A dynamic performance test was carried out using a 100kg articulated dummy wearing a 2-point harness.
The dummy was attached via the front d-ring to a SKR type rope grab device that was in turn connected to an 11mm EN 1891 rope and Manuchroche connector and positioned to face the ladder. The ladder was secured via a tensioned ratchet strap to a single anchor.
Result = 100kg articulated dummy arrested by SKR rope grab device. Peak force recorded at harness attachment = 2.82kN. Peak force recorded at tensioned ratchet strap 0.66kN.
SPC0180169/0946
The test was designed to determine the effects of repeated loading on the structural integrity of a EN131 type aluminium portable leaning ladder.
The test ladder was installed against a solid surface. A ratchet strap was passed through the rung at the mid-point of the ladder and in turn attached to a tensile test machine via a length of rope passed through a free-running pulley. A load was applied at an angle of 45degs to the vertical plane of the ladder via the tensile testing machine. The load was increased to 161kg over a time period of approximately 15 seconds, then released. This cycle was repeated a total of 7500 times.
Results = Following a total of 7500 cycles, no visual evidence of damage was noted to the ladder rungs or stiles.
SPC0180854/0950
The test was designed to determine the effects of applying a dynamic load to an EN 131 portable leaning ladder that had been repeatedly loaded (ref: SPC0180169/0946).
A dynamic performance test was carried out using a 100kg articulated dummy wearing a 2-point harness.
The dummy was attached via the front d-ring to a SKR type rope grab device that was in turn connected to an 11mm EN 1891 rope and Manuchroche connector and positioned to face the ladder. The ladder was secured via a tensioned ratchet strap to a single anchor.
Results = No visual damage was noted to the ladder rungs or stiles.
Axial Load Testing of Ladder Tie Bolts
Axial load testing has been carried out on CSS Worksafe products ‘LADEYE_22’ and ‘LADEYE_26’ in a range of typical substrates.
N.B. Slight variances in values between material may be due to variances in torque values of installed ladder tie bolts as they are hand tightened. Note that in use the bolts are loaded at an angle of 45 65degs rather than in adirect axial plane.
Restrain yourself
The often baffling conversations that height safety experts find themselves involved in concern the simplest of subjects. One such matter appears to be the lack of understanding regarding what makes up a restraint system and what often is perceived as such, when it is apparent that a fall can take place.
When put in the context of fall protection the word ‘restraint’ takes on an important and far reaching significance, for operatives and managers of health and safety alike. For operatives, the choice to restrain is sensible and can be a life saving decision. For managers, controlling possible life threatening activities it has particular value, not least of which is the possible repercussions of making the wrong choice with fall arrest equipment and the subsequent consequences – both moral and legal – when things go wrong.
What constitutes a restraint lanyard? This appears to be a frequent puzzle for some users and those responsible for the selection and provision of this most simple of items. Does a restraint lanyard require an energy absorber? Can I use an energy absorbing lanyard for restraint? Clearly a lanyard that is not required to arrest a fall does not require an energy absorber, and an energy absorbing lanyard may also be used to restrain. However, the lanyard is only part of the problem/solution.
Often little or no understanding of the attachment point requirement has been considered. If attaching to a fixed anchorage, ensure that the lanyard that has been provided does not allow the person to reach a fall position. Common sense you may say! However, where fixed anchorages have been provided for attachment of restraint equipment, at the point of install a fixed length lanyard or some other restraining method should have been supplied, to ensure that no fall occurs.
Unfortunately when contractors attend site, the user equipment originally supplied is often not available to them and little or no information is given, or indeed adequate checks put in place to enable the correct choice of lanyard to be made. This can have dire consequences for the user.
The situation can be made considerably worse when the operative is connecting to a horizontal lifeline, as deflection needs to be calculated to ensure that no fall occurs. When working in close proximity to an edge or around openings, consider the possibility of a forward tip and whether this will turn restraint into fall arrest.
Frequently I am asked about suitability of anchor points and often when carrying out site inspection visits, our engineers find that lifting eyes have been installed, instead of fall arrest eye bolts.
In order to ensure that users are safe, it should only be fall arrest eye bolts (EN795, single point anchor) that are used for attachment of fall protection equipment. Eye bolts installed for lifting are likely to have been loaded frequently and weakened. When EN795 anchors are used and the single point anchor or flexible/ridged system is inspected, maintained, clearly marked, and in date, the user can be assured that when used with the correct user equipment the anchor will perform satisfactorily.
Installer organisations should ensure that adequate signs are clearly placed, in order that the user can be aware of what the anchor has been designed for, and what user equipment should be used to ensure safety.
Lanyard selection for Mobile Elevated Work Platforms (MEWP) appears to be a problem for some operatives. The rule should be restraint. The lanyard needs to be an adequate length to enable the operator to access and use the controls while ensuring that they cannot raise themselves above the handrail, or lean through to the extent that a fall can occur. The use of an energy absorbing lanyard is not recommended, as this may encourage a false sense of security. However, if used it is acceptable if the length does not allow the operator to reach a fall position. MEWPs are not designed for dynamic loading.
Published: 10th Jul 2010 in Health and Safety International
