The systematic integration of Human Factors into safety analyses: an integrated engineering approach

The performance of the human reliability analysis (HRA) and integration of its outcomes into quantitative risk assessment schemes remains quite a difficult and complex task to perform. Even worse is the assessment of organisational reliability assessment. The reasons of this difficulty mainly lay on the absence of a generically accepted paradigm that enables engineers to include systematically human and organisational factors (H&OF) into the analysis. Broadly speaking, engineering approaches very often account for error of omission forgetting the errors of commission (EOC), and, on top of that, they do not make any macro distinction between pre- and post-initiating human failures. This paper offers a paradigm on how to integrate H&OF into safety analysis by means of the recursive operability analysis (ROA), which has been adapted to accommodate H&OF, and renamed integrated recursive operability analysis (IROA). By means of a practical example, the method will illustrate how to account for H&OF in a systematic and consistent manner using an engineering approach. The paper will even provide a paradigm for the construction of integrated fault trees consistent with the IROA framewor

Risk awareness versus risk assessment in manufacturing: A field study

Risk assessment in manufacturing work environments gives a relevant contribution to health and safety management for the operators: hazards are identified, and the associated risks are quantified in order to promote the risk mitigation and to improve the safety level for all the workers involved. In this paper the relation between the risk assessment performed by Safety managers and workers' risk awareness is investigated using as case study a manufacturing plant (heavy vehicles) in Northern Italy. Risks are assessed with a set of widely used procedures and methods that return a level of risk related to each workplace. According to the most recent Italian regulation on safety at works (D.Lgs. 81/08) each worker has to be informed and trained about all risks he would be exposed to during her/his working activity. Operators are the final stakeholders of this process that started with a risk assessment performed by experts and ended with a transmission of information involving safety, personal health and working behaviour. To compare risk assessment and risk awareness, a field study was performed with more than 50 workers surveyed on their personal awareness of level of risk associated to their working task. The comparison highlighted significant miss-matches that are here discussed. To solve this miss-match a review of safety information methods and safety training for workers was identified as countermeasure

Operators’ risk awareness towards operations’ risk assessment: a field study in the motor vehicle field

Purpose: The purpose of the research was to verify if there was an alignment between the risk assessed and the risk perceived or if some inconsistencies arise that could affect the safety of the operators. In fact, eventual inconsistencies should be analysed, interpreted and managed to maximise the information and training process, if needed. Design/methodology/approach: The adopted approach in this work relies on the collection of the perception of the operators about the level of risk in a work environment and its comparison with the level of risk assessed by the company. The collection of data was performed through a survey designed ad hoc, subministrated to all the workers in the area under study, being them involved in the production and in the maintenance. The survey’s structure and aim were described to the operator by the researchers and returned by the operators in a voluntary and anonymous way. Findings: The information collected allowed identifying a gap between the risk assessed and the risk perceived by the plant operators. For example, for the use of personal protective equipments, the data highlighted a discrepancy between the knowledge about their need and the behaviour in using them, which resulted in the revision of both communication and training processes, with the adoption of a more participatory approach. Originality/value: The originality of the work is in the data set, originally collected for this study, in the data collection form, also devised specifically for the case under study, despite it can be easily adapted for other work environment, and in the purpose itself, aimed at pushing risk assessment towards a personalised and adaptive approach

Multivariable Based Decision-making for the Maintenance Strategy of Process Equipment

Nowadays, several pieces of equipment are running over their expected life-time. An equipment revamping could solve the situation, but, it is often not possible for economical reasons, regulatory constraints, etc.. The aging of the equipment can also cause safety problems: between 1980 and 2006, the Health and Safety Executive estimated that around 28% of the major incidents occurred in the period, corresponding to 96 accidents, could be traced back to plant aging. These accidents costed more than 17,000,000 € (Horrocks et al., 2010). A correct maintenance of the equipment can extend the plant life, increase the plant efficiency and maintain an adequate level of safety. Plant management can choose among different maintenance strategies. The choice can be influenced by parameters as: the maintenance cost, the equipment condition before the maintenance, the lack of production cost, the safety of the operator during the maintenance and during the normal operations. In this paper, a multivariable Fuzzy approach is proposed in order to support the decision between different maintenance strategies through the analysis of their peculiarities, helping the management to weight the pros and cons of the alternatives. This approach is applied to a case study related to the maintenance of process equipment: it highlighted that the full refurbishment of a turbine blades system is a maintenance approach as valid as the current maintenance procedure, while the adoption of new technologies resulted not convenient

An empirical approach to workload assessment for process optimization

The Human Factors contribution in the scope of the industrial process optimization presented in this case study had to deal with considerations regarding the physical and mental workload requirements of different workstations and the capabilities of the operators assigned to them. The scope was to provide the industrial management with a better way to allocate human resources to tasks having different workload requirements. This work presents an empirical model designed to quantify the impact of workload on workers with the aim of reducing operational errors and safety human errors. The effects of this workload assessment can contribute to consider necessary areas of improvement in terms of technical measures, procedure optimizations and improved work organization, to reduce defects and waste generation. The paper presents a brief description of the empirical approach used to assess the workload of complex tasks in assembly lines; furthermore, it also discusses some of the preliminary results of its application

Risk assessment in freeze-drying processes

The risks identification is a key step for the safe design of a manufacturing process and, in this framework, once the threats to the process have been pointed out, it is important to evaluate their consequences, as well as their causes. In this paper, the risk assessment has been used to build the basis for the risk-based decision making in plant and process design of a pilot scale freeze-dryer, to be then exploited in the design of a full scale safer plant, taking into account also the experimental evaluation of possible human errors

The effect of human error on the temperature monitoring and control of freeze drying processes by means of thermocouples

Monitoring product temperature is mandatory in a freeze-drying process, in particular in the process development stage, as final product quality may be jeopardized when its temperature trespasses a threshold value, that is a characteristic of each product being freeze-dried. To this purpose thermocouples are usually inserted in some of the vials of the batch to track product dynamics. The position of the thermocouple inside the vials strongly affects the reading of the temperature evolution during the freeze-drying process and, thus, it is necessary to place them in the right position, in such a way that correct information about product temperature is obtained. In this work, at first, the probability of the operational error resulting into a wrong positioning of the thermocouple inside the vial has been estimated experimentally. Then, the effect of this error has been assessed in terms of risk of exceeding the limit temperature in the primary drying step. Both 4R and 10R vials have been considered, and the investigation evidenced that the probability of incorrect thermocouples placement can reach 30% for 10R vials, and about 32% for 4R vials. These probability values increase, respectively, to 47 and 39% when the trays containing the vials are shifted to their final position. Then, through IR thermal imaging it has been possible to evaluate the temperature gradients in a vial, pointing out that the temperature difference between the product at the center of the vial, where the thermocouple is supposed to be, and that of the wall, that is quite often measured by the thermocouples, can be about 1°C. Therefore, associated to each thermocouple reading there is a probability distribution of product temperature. These figures can be used to assess the risk of exceeding the limit temperature in a freeze-drying process and, thus, to quantify suitable safety margins when evaluating thermocouple readings to take into account the operational errors, given a risk tolerability criteria

Human performance in manufacturing tasks: Optimization and assessment of required workload and capabilities

This paper discusses some examples where human performance and or human error prediction was achieved by using a modified version of the Rasch model(1980), where the probability of a specified outcome is modelled as a logistic function of the difference between the person capacity and item difficulty. The model needs to be modified to take into account an outcome that may not be dichotomous and o take into account the interaction between two macro factors: (a) Task complexity: that summarises all factors contributing to physical and mental workload requirements for execution of a given operative task & (b) Human capability: that considered the skills, training and experience of the people facing the tasks, representing a synthesis of their physical and cognitive abilities to verify whether or not they are matching the task requirements. Task complexity can be evaluated as a mathematical construct considering the compound effects of Mental Workload Demands and Physical Workload Demands associated to an operator task. Similarly, operator capability can be estimated on the basis of the operators' set of cognitive capabilities and physical conditions. The examples chosen for the application of the model were quite different: one is a set of assembly workstation in large computer manufacturing company and the other a set of workstation in the automotive sector. This paper presents and discusses the modelling hypothesis, the interim field data collection, results and possible future direction of the studies.

Atex‐HOF methodology: Innovation driven by human and organizational factors (HOF) in explosive atmosphere risk assessment

ATEX (explosive atmosphere) risk assessment is required when any equipment or system could generate a potentially explosive atmosphere. Despite the fact that many operations on plants and equipment containing dangerous substances are performed by operators, influences of human and organizational factors (HOF) are mostly neglected in the ATEX risk assessment. The integrated methodology described here is proposed to address two challenges: (1) identification of the HOF influence on the ATEX risk assessment, and (2) quantification of the HOF influence. The proposed methodology enriches the traditional ATEX risk assessment procedure, which consists of four steps: (1) area classification, (2) ignition source identification, (3) damage analysis, and (4) ATEX risk evaluation. The advantages of the ATEX‐HOF methodology are demonstrated through the application to a paint mixing station in an automotive manufacturing plant. The ATEX risk assessment methodologies are mainly semi‐quantitative. The ATEX‐HOF methodology provides a quantitative analysis for the area classification and ignition source identification, and a semi-quantitative approach for the damage analysis. As a result, the ATEX‐HOF risk evaluation becomes more accurate. An event tree‐based probabilistic assessment has been introduced, considering both the technical barrier failure (Prtbf) and the human intervention in terms of human error probability (HEP). The case study allowed for demonstrating how taking HOFs into account is particularly important in companies where the safety culture is lower and consequently, the usual hypothesis of the correctness of operator intervention (in maintenance, normal operations, and emergency) could bring to non‐conservative results

Preliminary risk assessment of ecotoxic substances accidental releases in major risk installations through fuzzy logic

In the present work a fuzzy logic model to preliminary assess the risk of accidental releases of ecotoxic substances in hazard plants has been developed. The methodology is based in three steps, the characterization of the hazardousness of the substance, the delimitation of the soil and groundwater vulnerability and the identification of the protective and preventive measures of the plant. The tool has been tested with a set of storage yards of ecotoxic substances, mainly oil, in the Regione Piemonte area (Italy). The results obtained are in good agreement with the real situation of the surveyed storage yards. Thus, by using this methodology it is possible to preliminary assess the risk from uncertain data.Peer ReviewedPostprint (published version