Improving Mining Equipment Safety Through Human-Centered Design

Mining Equipment-Related Incidents and the Lack of a Human-Centered Design Focus

Human-centered design (HCD) is an increasingly influential approach in many work domains, in part because of a growing recognition of the contribution of design to occupational safety (Horberry & Burgess-Limerick, 2015). HCD is a process that aims to make equipment and systems more usable and acceptable by explicitly focusing on the end user, his or her tasks, and the work environment or use context. It requires that users and other stakeholders are involved throughout the design and development of the equipment or system (International Organization for Standardization, 2010).

HCD is also intended to eliminate workplace hazards by systematically involving end users in the design and evaluation of mining equipment. In this safety aspect, HCD links closely with the aims of the Prevention through Design initiative for “designing out” hazards (Horberry, Burgess-Limerick, & Steiner, 2015).

The mining industry is experiencing rapid growth in the design and deployment of smart devices, teleoperation systems, and new mining equipment. Such systems should be designed to be safe, effective, and usable by focusing on the end user. However, to date, HCD has not been widely applied to the design, development, and deployment of mining equipment or new technology (Horberry & Lynas, 2012).

Designers of mining equipment face a challenge in that the environments in which such equipment will be used are highly variable. Weather, mining method, workforce demographics, and operational procedures are some of the variables (Horberry, Burgess-Limerick, & Steiner, 2011). Therefore, design and risk assessment tools must be considered through the entire life cycle of mining equipment, especially when equipment is being designed by original equipment manufacturers and when it is being commissioned at a mine site.

Developing a Human-Centered Safe Design Tool for Mining Equipment

Until fairly recently, there has been an absence of a standardized and widely accepted overall occupational safe design methodology. We believe that the American National Standards Institute Standard Z590.3, Prevention Through Design: Guidelines for Addressing Occupational Risks in Design and Redesign Processes (ANSI, 2011), may help to resolve this situation, particularly as it offers a broad framework for safe design.

We aligned the OMAT tool with the ANSI Z590.3 standard. OMAT was originally developed and employed for equipment used in the minerals industry (Horberry, Sarno, Cooke, & Joy, 2009). Being a task-based process, OMAT could help designers identify, comprehend, and provide solutions to risks that users face when operating and maintaining equipment (Horberry et al., 2011). The seven stages of the OMAT process are shown in Figure 1.

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Figure 1.

Operability and maintainability analysis technique (OMAT) seven-stage methodology.

The OMAT methodology first identifies the critical operational and maintenance tasks to be undertaken with the equipment. Then, in a workshop with end users, the different steps in these key tasks are established, especially noting how they are done in actual mine site conditions. The members of the end user workshop then assess the risks at each task step and propose draft solutions where needed. These draft design/redesign solutions are then iteratively developed and evaluated, and the whole OMAT process is documented.

The OMAT method was fully described by Horberry and Burgess-Limerick (2015); in this article we focus on the outcomes of applying OMAT to the specific issue of mining equipment access and egress. As noted later, its application demonstrated the importance of obtaining end user input to reveal design deficiencies and to identify effective human-centered redesigns.

OMAT Case Study: Safe Design of Mobile Mining Equipment Access and Egress

Our focus here is access and egress for both operators (drivers) and maintenance personnel. Access and egress have historically been high-risk tasks related to mobile machinery; Leskinen et al. (2002) noted that nearly 50% of incidents associated with such machinery occurs during access and egress, mainly to and from the operator’s cabin. More recently, Cooke (2015) similarly found that a large number of incidents were linked to access and egress in an analysis of U.S. and Australian incident data.

As shown in Figure 2, getting into and out of an operator’s cabin on mobile mining equipment can sometimes be a precarious and high-risk process. Additionally, at a mine site, a large amount of dirt and debris tends to accumulate on the step during operations, as shown in Figure 3.

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Figure 2.

Accessing a bulldozer’s cabin: (a) bulldozer alone, (b) bulldozer with an operator attempting to access cabin.

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Figure 3.

Dirt and debris on a bulldozer’s access step.

We applied OMAT to this issue for a global mining company. It occurred in a workshop format with participants from advisory groups, local management, human factors and safety specialists, and local operators and maintainers. Generally about eight personnel attended each workshop. OMAT workshops related to the specific issue of access and egress for surface mining equipment, such as bulldozers and haul trucks, occurred in Australia, Indonesia, and Peru.

All the OMAT workshop groups began by brainstorming the types of access and egress tasks performed and the different environments in which they are performed at the mines. In total, up to 20 tasks were identified for consideration. For this article, that number was reduced to tasks performed only by the operators, rather than the maintainers, accessing the truck cab. Essentially these tasks were getting into and out of the cab.

These tasks were viewed by the workshop participants at the mine site and also video-recorded for additional analysis. An experienced operator and an inexperienced person accessing and egressing the equipment were viewed performing these tasks at the mine sites. Thereafter, back in the workshop setting, task flow charts were created for the access and egress tasks, which broke down each task into task steps, not unlike a conventional hierarchical task analysis (Kirwan & Ainsworth, 1992). Then, workshop participants explored the risks for each task step, and redesign solutions were developed by the group. Table 1 shows an example of this process for the first task step when accessing a bulldozer’s cabin.

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Table 1.

Example of Operability and Maintainability Analysis Technique (OMAT) for One Task Step During Access

Task Step	Possible Design Deficiencies	Current Controls	Redesign Controls Identified in the Workshop
1	Potential slip to ground or into push arm Step quite narrow and can be coated in mud/rocks from operation	A step to assist with access/egress	• Install a ladder system from the cab side platform to the ground, including maintainability as part of the review. • Increase step size. • Provide tools for cleaning step. • Remove steps on front of tilt arm, which seem to catch mud/rocks. • Add handrails.

One strength of OMAT was giving a site-based mechanical engineer or maintainer a clear understanding of the problem to be solved. The video of tasks being performed was of particular assistance for the workshop group to develop a solution. The redesigned solutions went through several iterations, involving user trials in the mine site maintenance areas and further OMAT workshops to help refine them. Figure 4 shows the first iteration of a single hand post to assist equipment access and egress.

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Figure 4.

First redesign iteration: (a) bulldozer alone, (b) bulldozer with an operator accessing cabin using the hand post.

We found that the first design enabled an operator to maintain an upright posture and, generally, at least two points of contact. However, there was a tendency for the operator to swing around the hand post and potentially lose contact. Therefore, a second iteration was developed, as shown in Figure 5.

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Figure 5.

Second redesign iteration: (a) bulldozer alone, (b) bulldozer with an operator accessing cabin using the two hand posts.

The second iteration helped an operator to maintain three points of contact. It also helped to constrain his method of access/egress to the designed/prescribed solution (rather than swinging around the hand posts). However, a subsequent workshop revealed that the designed hand posts should be extended farther forward and backward to be of greater assistance to the operator (see Figure 6).

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Figure 6.

Third redesign iteration: (a) bulldozer alone, (b) bulldozer with an operator accessing cabin using the two redesigned hand posts.

Formal evaluation of the final design iteration has not occurred. But risk reranking in our participatory ergonomics group found that the likelihood and severity of incidents at the different task steps were reduced. Also, on a practical level, the mining company involved in these trials now requires all new surface earthmoving equipment to have its access/egress assessed using an OMAT-style assessment prior to being used.

Conclusions

We believe that the application of OMAT to mobile mining equipment already in use in operational conditions is extremely useful in two ways.

First, it helped to better identify issues. Our OMAT process proved to be very useful in identifying specific equipment-related issues. After tasks were broken down into flow charts, the issues were more apparent, making it easier to suggest redesign changes. For instance, the OMAT identified issues not in previous risk assessments, such as “nonprescribed” methods of access/egress.

Second, it helped to challenge assumptions. The videotaping and viewing of tasks were successful in breaking down false assumptions held by OMAT participants. Our workshop members indicated that it forced more detailed and realistic assessment of work than was done at mine sites. For example, it was assumed that the “emergency” egress ladder would be more dangerous to descend than the routine access/egress method. However, the handrails on the main access/egress method did not extend above the final step, requiring an operator to release the ladder with both hands at some stage before reaching the upper platform. The handrails for the emergency ladder went above the height of the deck. This design allowed the operator to place his feet on the deck before releasing the ladder.

We have learned a number of lessons through the application of the OMAT process, perhaps the most important of which is having an appropriate time frame for the desired scope. This time frame is necessary to allow in-depth scrutiny of tasks and to help the redesign process. As previously found by Horberry et al. (2009), a couple of days per task may be required.

Additionally, having input from workshop participants from different backgrounds through a central facilitator was important. The workshop format enabled effective discussion among safety professionals, human factors facilitators, designers, and end users.

The redesigns for the aforementioned access/egress results were consistent across multiple sites and workshop facilitators, providing evidence that the process is robust enough to be transferable to different mine site contexts and mining personnel. This process includes task observation on the actual (and any proposed) access/egress systems.

The work described in this article focused on redesign of equipment after it has been deployed. Ideally, risks would be “designed out” before the equipment arrived on site. Therefore, further work with manufacturers of original mining equipment to better bring end user perspectives is our strong recommendation. Recent work by Horberry and Cooke (2012), investigating the ways a major original equipment manufacturer obtained end user feedback, and by Burgess-Limerick, Joy, Cooke, and Horberry (2012), to help mining companies better assess equipment-related risks during procurement, are both promising steps forward.

In conclusion, we found that the participatory, task-based nature of the OMAT process makes it suitable for a wide variety of global mine sites. In essence, our efforts showed that focusing on end users and their tasks, and applying an iterative human factors and structured risk-management design process, can help to achieve safer redesigns of mining equipment.