Minimum Clearance Distance in Fall Arrest Systems with Energy Absorber Lanyards

Accidents due to falls from height are one of the main causes of death in workplaces. Fall arrest systems (FAS) are designed to arrest the fall safely without injuring the accident victim. Their main mission is to restrain the body so as to prevent it from hitting the ground, generating forces and accelerations in the arrest process that are not harmful. A lack of empirical evidence and scant technical information provided by manufacturers regarding minimum clearance distance (MCD) below anchorage makes it necessary to study the safety distances required in the use of Energy Absorber Lanyards (EAL). This paper aims to determine the MCD below anchorage to arrest a fall using an EAL without hitting the ground. The real deformation of EAL when stopping a fall is studied. Ten EAL models distributed internationally by six manufacturers were chosen. Dynamic behavior tests were performed on the samples. Using image processing the total elongation of the equipment (elastic plus plastic) is obtained. The main conclusions are that maximum plastic elongation could be reduced by 29%. The method described in EN 355: 2002 underestimates elongation by up to 70% for some equipment 20% of EAL’s exceed the maximum arrest force (Fm) allowed in EN 355. The MCD data provided by manufacturers is not reliable. The data provided by manufacturers are incomplete. It is recommended that quality control for EAL’s be strengthened to ensure that products launched onto the market meet the requirement of EN355. The findings of this study recommended increasing MCD distance longer than that calculated according to EN355, at less than 1 m.

Automated Positioning of Anchors for Personal Fall Arrest Systems for Steep-Sloped Roofs

Falls account for about one-third of all construction fatalities with most fatalities in the roofing trade. Even though a personal fall arrest system (PFAS) is required for fall protection, proper placement of PFAS anchor points is an issue evidenced by the high number of fatalities caused by incorrect anchor positioning. The research goal was to proof the concept of optimizing the location of the PFAS anchor points on steep-sloped roofs. This goal was achieved by: (1) Developing an algorithm for converting the required local jurisdiction construction regulations and standards for PFAS anchor positioning into machine-readable rules; and (2) Developing and validating an algorithm for optimizing the location of PFAS anchor points. The K-Nearest Neighbor Search (KNNS) optimization algorithm was selected in this research and was implemented into a standalone computer tool using Python programming language. The tool calculates the potential anchor locations that satisfy the fall clearance and swing hazard requirements and then displays the anchor locations both graphically and numerically. The optimization algorithm was validated using the K-fold Cross-Validation method, which proved the algorithm was adequately accurate and consistent. The research contribution is the proof of the concept that the development of an optimization algorithm and automated field-level tool for optimal selection of PFAS anchor points is possible, further research and refinement could help steep-sloped roofing companies improve their safety practices.

Average Force of Deployment and Maximum Arrest Force of Energy Absorbers Lanyards

Energy-absorbing lanyards (EAL) are part of fall arrest systems (FAS), their main mission is to dissipate the energy generated during the fall, ensuring that the arresting force does not cause injury to the user. For the design of FAS as set out in the American standard Z359.6 and the Canadian Z259.16 it is essential to know the deployment force or average arrest force (Fa). Fa is necessary to estimate the elongation that the absorber will suffer during the fall and therefore essential data to calculate the clearance distance. There is a lack of useful experimental data for the design of this personal protective equipment (PPE). This work provides empirical data required for the design of FAS with EAL in accordance with EN 355. This paper covers different types of EAL that are marketed internationally; different empirical data, average and maximum forces, required for improving safety design are researched. Six manufacturers, 10 models, and 2 samples of each model were selected, with total of 20 tests being performed. Dynamic performance tests were carried out, the free fall of a person was simulated using a 100 kg steel ballast from the maximum height allowed by the equipment, obtaining the maximum arrest force (Fm), average deployment force (Fa), and, by calculating the balance of forces, the maximum and average acceleration suffered by the ballast during its arrest. In light of the results, relevant conclusions for user safety are obtained. It is feasible to raise the safety requirements established by the different standards. The Fm can be established below 6 kN in the EAL, and the Fa can be estimated at 87.5% of the Fm. The categorization of the force–time curve in fall arrest with EAL has been obtained. Two EAL purchased on the market exceed the Fm permitted, therefore it is recommended to increase the quality controls of EAL.

Suspension Trauma

Fall harnesses have become much more prevalent for those that work at heights. Safety harnesses and fall arrest systems are commonly used by the construction industry, mountain climbers and other recreational activities where fall risks are a concern. Through the efforts of occupational health and safety legislation, job site safety programming and workplace harm reduction culture, there is a growing understanding of how and when to don these safety devices and the potential perils associated with their use. However, there is a paucity of information within the healthcare community in how to clinically manage a patient who has suffered a pattern of injury that can arise from these devices - known as suspension trauma. This condition may also be termed as harness-induced pathology, orthostatic shock while suspended and harness hang syndrome. This article helps to increase awareness and understanding of what suspension trauma is and how to pragmatically manage this condition from both a prehospital and emergency department perspective.

Search and recovery of aircraft parts in ice-sheet crevasse fields using airborne and in situ geophysical sensors

On 30 September 2017, an Air France Airbus A380-800 suffered a failure of its fourth engine while over Greenland. This failure resulted in the loss of the engine fan hub, fan blades and surrounding structure. An initial search recovered 30 pieces of light debris, but the primary part of interest, a ~220 kg titanium fan hub, was not recovered because it had a different fall trajectory than the light debris, impacted into the ice-sheet's snow surface, and was quickly covered by drifting snow. Here we describe the methods used for the detection of the fan hub and details of the field campaigns. The search area included two crevasse fields of at least 50 snow-covered crevasses 1 to ~30 m wide with similar snow bridge thicknesses. After 21 months and six campaigns, using airborne synthetic aperture radar, ground-penetrating radar, transient electromagnetics and an autonomous vehicle to survey the crevasse fields, the fan hub was found within ~1 m of a crevasse at a depth of ~3.3 to 4 m and was excavated with shovels, chain saws, an electric winch, sleds and a gasoline heater, by workers using fall-arrest systems.

New test method with a Hybrid III Anthropomorphic Dummy for Textile Safety Harnesses

A full body harness is a basic component of personal fall arrest equipment. It is made from webbing connected by seams and metal fittings to firmly hold and support the user’s body. The paper proposes a new method for full body harness testing using a Hybrid III anthropomorphic dummy; also the design of the experimental stand and software used are described. The method analyses the behaviour of a dummy during a fall arrest under well-defined conditions. The critical mechanical factors measured during the study presented were: the head acceleration, forces acting on the spine, the position of the dummy, the impacts of harness elements to the head, etc. The tests identified some potentially dangerous phenomena associated with falls from a height. The harness testing method developed turned out to be a valuable tool that should be applied in conjunction with existing strength testing methods.