Risk & Safety Gerenciamento de Riscos e Segurança: FATORES HUMANOS

Risk & Safety

Original Language

Conceitos Básicos de Fatores Humanos e Erro Humano

Acredita-se^{^[1]} que entre 50% e 90% dos incidentes industriais sejam atribuídos a erros humanos. A análise de falha humana lida com as falhas que as pessoas podem cometer em suas interfaces com os processos de engenharia. Quanto mais cedo a análise de falha humana é realizada maior a sua eficiência em reduzir a probabilidade de erro humano, por isso é importante uma abordagem baseada na análise de falha humana desde a fase de projeto.

As falhas humanas e suas conseqüências são influenciadas diretamente pelo “Projeto para Fatores Humanos” do empreendimento tecnológico como todo. Chamamos de Fatores Humanos aqueles os quais podem aumentar ou diminuir a possibilidade do homem cometer erros, sendo esses fatores estabelecidos como resultado de um projeto ou empreendimento tecnológico. Ou seja, o Erro Humano pode ou não acontecer dependendo dos Fatores Humanos envolvidos na interação Homem X Máquina criada pelo projeto ou empreendimento tecnológico.

Qual o significado prático do termo “Fatores Humanos” ?

Toda máquina ou instalação projetada, seja uma indústria, um automóvel, um edifício, um telefone celular, um notebook, um avião, um videogame, enfim qualquer equipamento, instalação ou empreendimento tecnológico sempre interage de algum modo com o ser humano. Essa interação homem x máquina pode ser previamente estudada e projetada para máxima eficiência e segurança, ou pode simplesmente resultar do andamento natural do projeto sem receber uma atenção específica. Os fatores envolvidos nessa interação homem x máquina são chamados de “fatores humanos” e o estudo e projeto de adequação destes fatores permitem a proteção contra o ambiente de indução ao erro humano, principal causa de acidentes indetificada pelas investigações oficiais.

Cockpit de Aeronave - Interação Homem x Máquina

no centro do controle da segurança do vôo

Qual a origem do termo ‘Fatores Humanos” ?

Predecessora dos “Fatores Humanos” a Ergonomia surgiu como conseqüência dos problemas de projeto e problemas operacionais que emergiram com os avanços tecnológicos ocorridos no século XX. Teve como precursores o Gerenciamento Científico desenvolvido por Taylor[2] e o Estudo do Trabalho desenvolvido por Gilbreth[3]. É uma disciplina híbrida, que surgiu quando cientistas passaram a atuar em conjunto para resolver problemas complexos e multidisciplinares. Os principais campos científicos que deram origem a Ergonomia são: Engenharia, Psicologia, Anatomia, Fisiologia e Física (principalmente mecânica e física ambiental). Também sofre especial influência das disciplinas emergentes: Engenharia Industrial, Desenho Industrial e Teoria de Sistemas.

Várias tendências podem ser identificadas ao longo do processo de desenvolvimento da Ergonomia. Primeiramente as organizações tentaram melhorar a produtividade introduzindo novos métodos e máquinas. Na era da engenharia pura isso funcionou porque havia grande espaço para desenvolvimento tecnológico uma vez que a mecanização dos processos era recente. Posteriormente tentou-se aumentar a produtividade otimizando o projeto das tarefas e reduzindo os esforços improdutivos. Depois da Primeira Guerra Mundial um movimento surgiu estimulando o desenvolvimento de testes psicológicos com o objetivo de medir várias características humanas como inteligência e personalidade.

Historicamente em 1857, Jastrzebowski[4] produziu um tratado filosófico de Ergonomia: “The Science of Work” o qual aparentemente permaneceu desconhecido fora da Polônia, até recentemente. Na Grã-Bretanha o campo da Ergonomia foi inaugurado depois da Segunda Grande Guerra. O nome “Ergonomia” foi re-inventado por Murrell em 1949 apesar dos temores de que as pessoas iriam confundir o termo com “Economia”. A ênfase da ergonomia era no projeto de equipamentos e do local de trabalho. Os temas relevantes eram anatomia, fisiologia, medicina industrial, projeto, arquitetura, e engenharia de iluminação. Na Europa, Ergonomia era ainda mais associada com as ciências biológicas. Nos Estados Unidos surgiu uma disciplina similar (conhecida como Fatores Humanos), mas sua rota científica era ancorada em Psicologia (Psicologia Experimental e Aplicada, Engenharia Psicológica e Engenharia Humana).

Fatores Humanos e Ergonomia tiveram sempre muito em comum, mas os seus desenvolvimentos seguiram linhas diferentes. Fatores Humanos coloca muito mais ênfase à integração dos aspectos humanos ao processo global de projeto de sistemas. Alcançou notável sucesso no projeto de grandes sistemas na indústria aeroespacial, em especial através da NASA e o do Programa Espacial Americano. A Ergonomia européia apresenta-se mais fragmentada e tem tradicionalmente sido mais associada às ciências básicas limitando-se a um determinado tópico ou área específica de aplicação.

Sala de Controle de Usina Nuclear - A Ergonomia e os

Fatores Humanos são Estudados para Evitar o "Erro Humano"

Apesar destas diferenças, não deve haver preocupação com relação ao uso dos dois termos: Ergonomia e Fatores Humanos. Nos Estados Unidos, a HFS - Human Factors Society recentemente modificou seu nome para HFES - Human Factors and Ergonomics Society[5]. Presume-se que essa mudança tenha sido feita para sinalizar a afinidade entre as áreas, justificando uma única associação para representar os interesses daqueles que se identificam como militantes tanto em uma como na outra área.

Atualmente ambas as áreas, Fatores Humanos e Ergonomia, adotam a abordagem ATH (Adaptar o Trabalho ao Humano) em substituição à velha e superada abordagem AHT (Adaptar o Humano ao Trabalho) e estabelecem que os trabalhos devam ser adequados para as pessoas ao invés de outras formas de abordagem que, embora se aproximem desse conceito, não o consideram como a base de sua filosofia.

[1] Fonte: Primatech Specialists in Safety, Security and Risk - USA

[2] Taylor. F.W. 1911. The Principles of Scientific Management. Harper and Brothers Publishers, New York and London.

[3] Frank Bunker Gilbreth, Sr. (1868 – 1924). Defensor do gerenciamento científico e pioneiro do estudo dos movimentos.

[4] Jastrzebowski, W. 1857, An Outline of Ergonomics or the Science of Work. Published by the Central Institute for labor Protection, Warsaw, Poland, 2000.

[5] HFES – Human Factors and Ergonomics Society. Internet Link: http://www.hfes.org/web/Default.aspx

Risk & Safety

Original Language

GPS and Human Factors

How do “Global Positioning System - GPS” capabilities and limitations affect your use of it ? How does using it for various tasks affect you ?

A study conducted under the guidance of Professor and PhD Louis Freund from San Jose State University – California USA, shows some aspects of the use of GPS.

GPS is an electronic device increasingly used to assist drivers in their localization tasks. Its operation[1] is based on a network of 26 satellites placed in orbits so that always at least five satellites are on the sky of a receiver on Earth. Only four satellites are sufficient to determine the altitude, longitude and latitude of the receiver antenna. With this system the user of a GPS device has a reference to secure its position and using maps and navigation software can drive a car to an address without any prior knowledge about the region. This is a complex system that requires a good software to interact with the driver in a quick, clear and precise, without diverting the attention of the driver of their security roles in driving the car.

Type of GPS Considered

There are several types of GPS that can be used by the driver of the car. Some drivers also use cell phones with GPS or other devices that are not specific for use in cars. We consider in this work only the devices sold specifically for use in automobiles. Discard the others for their totally inadequate because they do not have a suitable and their use can result in unsafe conditions and therefore cause accidents.

1 - How GPS Affects Driver ?

The dashboard of a car has been the target of studies of Human Factor and Ergonomics for decades. A driver must divide his attention with traffic, and the indications of the instruments on the dashboard of the vehicle. A failure of attention in traffic can result in an accident. But a failure to read the instruments can also cause many problems including accidents. If we add a GPS navigator to the panel of an automobile such problems are maximized, and a failure to understand an instruction of the GPS, can also result in accidents.

1.1 Position on Dashboard

The vast majority of vehicles sold browser does not have a GPS built into your dashboard. Only the most luxurious cars have this item as the original series. Even in these luxury cars, the presence of a built-in GPS panel significantly increases the demand for attention by the driver. That is, the driver who uses a GPS needs to devote more attention to the panel that the driver of a car without GPS. This is even more critical when the GPS is purchased and installed by the driver in the vehicle.

When GPS is part of the original panel of the car, the factory has studied previously the best position and facilitated the interaction of the driver with GPS. But in most cases it does not happen because drivers get a GPS and even without adequate knowledge try to fix it at one point apparently suitable vehicle. Compared to the original design of the panel of the vehicle, GPS can be considered a "foreign body" to which the panel was not prepared to receive. GPS is often misplaced and interfere with driver vision. Other times the power cord interferes with the movements of the driver. In other cases supports the GPS can not stand the heat and give off while the car is moving. The driver needs to demand attention for fixing the GPS.

1.2 Information in Audio

During the GPS navigation device informs the audio for the actions that the driver should do. Often the driver apart from using the GPS keeps the radio on, talking to another occupant of the vehicle and can still answer a call by cell phone on speakerphone. Some GPS can centralize all of these functions and send an audio signal to Bluetooth or FM radio of the vehicle. Thus, other audio functions are interrupted when the GPS sends an instruction. But it takes time and willingness to make the configuration of this system every day before driving.

1.3 Visual Information

The information for audio are not sufficient to guide the driver. So the driver who uses GPS need to share their visual attention between traffic and the GPS screen. Often the GPS screen is too small making it difficult to read, and sometimes so great that it impairs the vision of the street. It also happens a delay between the information in audio and visual information. This implies greater demand for visual attention of the driver.

1.4 Software and Settings

Despite all the efforts of designers, not all management software used in GPS maps are "friendly." Some are slow and slowing down in the middle of the work requiring a reboot often performed with the moving car. There is also a level of complexity in software configuration. There are different options for route calculation and recalculation when there is an error of the driver. The use of GPS requires a work of reasoning parallel to driving demanding mental effort and stress in some cases.

2 How Driver Affects GPS

For the best performance of a GPS navigator is necessary to know the instruction manual, the navigation software and configuration requirements. As not all drivers comply with these tasks, many GPS navigators are underutilized or not working properly and can even cause accidents.

2.1 Position on Dashboard

Lack of knowledge about how to fix the GPS panel can cause the downfall of the device while the driver drives. Also you must set the instrument at a location capable of receiving satellite signals. If the device is misplaced may stop working several times due to lack of signal from the satellites.

2.2 Information in Audio

The inadequate configuration of the audio system can interfere with GPS orientation. Some devices can centralize the functions of radio and cell phone when properly configured. Even though this is not done, you must configure the volume, type of language and especially the sound signals. Some GPS misconfigured emit many sounds that can barely be understood the guidelines for direction. Other GPS also misconfigured, seem dumb and do not provide the minimum information to fulfill your audio functions

2.3 Visual Information

Some screens of GPS have become extremely polluted with too much information because they had been misconfigured by the user. Others barely have the minimum information for failure in configuration by the user. Users who need glasses to see up close feel conflicted because they can not use these glasses to drive. GPS for these users is bad, but in reality the visual limitation is that the user makes the system bad.

2.4 Software and Settings:

Even if the driver is an expert knowledgeable of the manual and the navigation software, other features of the driver can make a big difference in system performance. Some GPS have screen-type touch screens. For the driver to interact on a screen so small and run at the same time it needs to have a skill and specific physical characteristics. A person with very large fingers can unconfigure the player completely in the middle of a trip to 65 mph, causing stress and increasing the risk of accidents. Often the driver does not have the ability to make quick decisions on the configuration of GPS while maintaining the coordination of movements of driving.This ability has great influence on the smooth functioning of the GPS system and driver.

General Conclusions

The GPS equipment is a useful orientation to the car. But the man machine interfaces need to be improved and developed.

The use of GPS affect the driver's attention in traffic and appliances improperly installed and not well configured can cause accidents.

The GPS user must have good knowledge about the use of equipment for the system to function properly. The choice of GPS should be adequate to the characteristics of the user considering the quality of your vision and hearing, and physical characteristics. The current stage of development of most GPS requires attempts to "fit the man to the job" (FMJ), which means an approach not very suitable for the type of product which must be able to work with every type of driver. Would further recommend the product development with an approach such as "fitting the job to the man" (FJM).[2]

The designers and traffic authorities should assess the need for a standardization on the visual and audio information for use in GPS. Each software generates alarms and their specific orders. A minimum standardization can facilitate the work of drivers to understand the commands of the GPS devices. One recommendation is to listen to hundreds of motorists who already use the GPS on the market, analyze their complaints to take them to implement improvements in new projects of GPS. As Bridger, R. S. "The participatory approach seems to be the best way to ensures that the implementation of ergonomics will be effective."2

The task of driving an automobile requires great attention and its implementation represents the safety of human lives. The current GPS mostly split the attention of drivers. Authorities with the technical expertise, together should seek appropriate solutions to standardize and use of technologies such as "HUD - Head Up Display"[3] so that the GPS can be used with maximum safety.

HUB - "Head Up Display". Source: Garantialsat

[1] Carla, Luísa, Natash, Raissa, Aprendendo Física, Colégio Pedro II, Rio de Janeiro Brasil.

Link: http://aprendendofisica.pro.br/alunos/index.php/cp2-102/2007/05/16/principio_de_funcionamento_do_gps

[2] Bridger, R. S. Introduction to Ergonomics, 3rd Ed. CRC Press, 2009

[3] Air Power, Austrália

Link: http://www.ausairpower.net/TE-Fighter-Cockpits.html

Risk & Safety

Original Language

Are You Sure You Use Your Laptop Properly ?

LAPTOP EVALUATION

1 – Introduction and Purpose:

The use of laptop is widespread in all activities. Some companies use no more desktops. All employees use laptops only. The employee can work in various offices of the company, establishing a workstation at each location. For this, the workstations have been modified and prepared for this new scenario. The main equipment is the laptop, which connects with all the corporate environment and with the rest of the world. But these same companies that have a high level of information technology, are not exempt from possible problems related to incorrect use of laptop for its employees.

This study will consider using the laptop for a external workers hired to work in a central control room of an Exploration & Oil Production Offshore Plataform, during the construction. The central control rooms of Offshore Oil Platforms meet standards of ergonomics in order to provide the best possible conditions for the operators' work. Many times consulting firms are hired to do the specific design of control rooms.

However, despite the central control rooms be considered almost an "ideal workstation", sometimes an operator or another employee uses a laptop in that area in inadequate conditions. This study will evaluate the conditions for working with laptop on the consoles of a central control room, even during the construction.

2 – Body Mechanics at Work:

We consider the man with the posture of the photograph (Figure 1) in Appendix, at 47 years old weighing 70 kg, with a working laptop on the console of a central control room under construction. We can observe:

Workstation Setup: The posture is not correct. But the arms works in your normal range of motion.

Sitting: The man is sitting relaxed, so the pelvis rotates backwards and the spine is flexed about 30 degrees. Source: SJSU PhD Louis Freund, class presentations

Posture: Sitting in a slouched posture. This represents approximately 180% of compressive disc pressure relative to the value when standing erect. We believe that the compressive force on L3 is 686 N to 100% of compressive disc pressure standing erect. Then the disc compressive pressure to the man in the photograph (Figure 1) of the appendix is about 1234.8 N. Source: apresentations class (adapted from Nachemson, 1975)

Hands: The man is not typing at the time of photography. But we understand that for man to do the typing posture of your hands will be ulnar deviation, pronation, and with slight flexion. Figure 1 shows two laptops in use. A standby with external mouse. Another actually in use, with mouse pad. In both cases, the workstation establishes a bad posture in which the hand need to work on posture flat and too high. Source: SJSU PhD Louis Freund class presentations.

Compressive Strength; According to the regression equation (Genaidy ET AL., 1993) obtained in the chapter 2 of Bridger, RS Introduction to Ergonomics, we arrive at the value below to CS L3-L4.

CS = - 13331.2 – (73.7 x Age) – (926.6 x Sex) + (403 x LMS) + (79.8 x BW)

CS = - 13331.2 – (73.7 x 47) – (926.6 x 1) + (403 x 46) + (79.8 x 70)

CS = 6402.3 N

Taking a margin of safety of 60%, we obtain a damage load of 3841.38 N. The applied load is 1234.8 N as calculated above, and in accordance with class presentation (adapted from Nachemson, 1975). The ratio of job demands to biomechanical tolerance is 0.32 (1234.8 / 3841.38); Thus, the applied load is safe in relation to spinal compression tolerance limits because the ratio is below one, but the task needs to be redesigned to be improved.

3 – Anthropometry:

The man in the photograph (Figure 1) of the Appendix can not be identified. The picture was purposely chosen and obtained during the construction and commissioning of a new Oil Platform.

For this study will be considered that the man in the photograph (Figure 1) is Brazilian and has the same anthropometric data measured in the class, in the same posture of the photo. In other words, this study assumes that the man on the photo is 70 kg and its anthropometric data are the ones that are in the "Anthropometric Worksheet - Laptop Project" (Appendix). Considered the same posture of the photo to measuraments.

The measurements are in centimeters because the effect of clothing on the estimates of user anthropometry can never be accurately predicted.

Calculation Percentiles:

avx + z.sd = x

consider:

avx = Table 3.3 Bridger, R.S. Introduction to Ergonomics, Brazil/UK male

sd = Table 3.3 Bridger, R.S. Introduction to Ergonomics, Brazil/UK male

x = measurement obtained, Brazil male

z = calculated

Percentiles from Appendix A Table - Bridger, R.S. Introduction to Ergonomics

Arm length (77,0 cm)

811 + z . 40 = 770 ; z = - 1.03

Percentile: 15

Buttock-knee depth (64,9 cm)

595 + z . 30 = 649 ; z = + 1,80

Percentile: 96

Popliteal height (42,5 cm)

425 + z . 24 = 425 ; z = 0

Percentile: 50

Sitting elbow height (27,8 cm)

230 + z . 28 = 278 ; z = + 1,71

Percentile: 96

Sitting eye height (71,8 cm)

775 + z . 34 = 718 ; z = - 1,67

Percentile: 5

4 – Static Work – REBA analysis

We used the "REBA Employee Assessment Worksheet" (Figure 3) of the Appendix. The analysis was conducted in relation to the photo (Figure 1) of the Appendix. The position of the employee was examined closely in relation to the position of the photo.

Although the employee may not be typing at the time of the photo, he is interacting with other colleagues who perform assembly work. We considered that for the most of the time the employee exchange information with colleagues and via your laptop check information to guide them. Therefore will be considered the position of the head turned to his colleagues as shown in the picture, because this is the position in which he spends most of the time.

Besides using the laptop, the employee also uses a list which is positioned in between the laptop and the end of the island that functions as a table. As space is insufficient, part of the list will not fit on the table. A power cord is also incorrectly positioned between the legs and the console / table.

The Final Score REBA was reached is 9. This means that the task is "high risk" and requires research and implement changes.

5 – Repetitive Work, Cumulative Trauma, Hand Tools:

An employee of the photograph (Figure 1) works within a central control room under construction. But this does not mean it's a temporary situation because after the construction of this control room is finished, the same employee is reassigned to another work of construction and assembly where it will perform its activities under the same conditions.

Thus we can consider that for the employee's photograph (Figure 1) this is your workplace routine. So the work under the conditions shown in the photograph may over time generate Cumulative Trauma Disorders (CTDs), Repetitive Motion Disorders (RMDs) and Work-Related Musculoskeltal Disorders (WMSDs).

The hand position for typing is not favorable to "The Natural Line", shown in Figure 4.It also does not favor the position wrists float, as shown in Figure 5 as the most correct position. The employee's attitude is not conducive to the use of hand tools, mouse, mouse pad, partly due to disorganization of the workspace.

6 – Evaluation

The situation presented in the photograph of Figure 1 provides a paradox. The main control room of an offshore platform is one of the most thoroughly studied in terms of ergonomics. All details are considered by the designer to ensure that operators have the best conditions to work. But even with all the quality in the design of control rooms, a certain group of employees works in conditions quite unfavorable.

These employees build a perfect room for their fellow operators, but over the years alternate in various control rooms under construction in working conditions that can cause Cumulative Trauma Disorders (CTDs), Repetitive Motion Disorders (RMDs) and Work-Related Musculoskeltal Disorders (WMSDs).

The ideal work is well known by those employees and in some cases, like the photograph of Figure 1, the employee works in poor conditions within the area to be ideal. At the end of the work of construction and assembly, the control room is equipped with ergonomic chairs, consoles, panels as shown in Figures 7 and 8.

7 – Conclusions and Recommendations:

Although the employee (Figure 1) to be working with a laptop, and is working on a unit under construction, the task needs to be redesigned according to the results of the REBA Final Score.

The job, even if temporary, must be regarded as a Visual Display Terminal and to approach as much as possible the pattern displayed in Figure 6 of Appendix. Some recommendations to improve the working conditions are presented below:

Replace the chair to get: Seat back adjustability; Good lumbar support; Seat height adjustability; No excess pressure on underside of thighs and backs of knees

Include foot support

Check the space for postural change, no obstacles under desk

Ajust the forearms approximately horizontal

Minimal extension, flexion, or deviation of wrists

Screen height and angle should allow comfortable head position

Check the correct space in front of keyboard to support hands/wrists during pauses in keying

Use a Document holder for lists

Distribute the employees in the workplace in order to wring the necks do not need to interact with colleagues who share the same task

Establish an appropriate point of electrical supply, so that the cables do not interfere with the work

Organization of the work area. Even though a construction site, the workplace needs to be better organized for the use of laptops

Employee training on ergonomics and consequences of failure in body posture during work

Identification and signaling of a specific place to use laptop. This site should be kept free and arranged to receive the laptop and provide the best working conditions for employees who use it, even during the construction phase or any maintenance after construction.