Access Systems on Mobile Plant: Why Standards Alone Are Not Always Enough

Safe access systems are a critical, and often underestimated, part of mobile plant design. Steps, ladders, walkways, and handholds are used every day by operators and maintenance personnel, often in difficult conditions and under time pressure.

While access systems for fixed plant are commonly designed to AS 1657, applying the same approach directly to mobile plant can lead to designs that are technically compliant, yet practically unsafe.

At Trang Imagineering, we regularly assist clients with the design, review, and certification of access systems on mobile plant, where the challenge is not just meeting a standard, but understanding how people actually use the machine.

AS 1657 (Fixed platforms, walkways, stairways and ladders) is widely regarded as the primary Australian standard for industrial access systems.

It works well for:

• Fixed structures

• Static plant

• Permanent access ways

• Controlled environments

However, AS 1657 assumes:

• A stationary structure

• Predictable geometry

• Consistent approach angles

• Limited interaction with moving equipment

These assumptions often do not hold true for mobile plant.

When AS 1657 is applied rigidly to mobile equipment, such as loaders, graders, haul trucks, or IT’s, the result can be access systems that look compliant on paper but introduce new hazards in practice.

Mobile Plant Is a Different Risk Environment

Access systems on mobile plant must contend with factors that fixed plant standards do not adequately address, including:

• Variable ground conditions

• Machine articulation and movement

• Vibration and dynamic loading

• Mud, dust, water, and contamination

• Changing access geometry as the machine moves

• Emergency egress requirements

Designing safe access in this environment requires different standards and additional engineering judgement.

ISO 2867 (Earth-moving machinery – Access systems) is often more applicable to mobile plant than AS 1657.

It is specifically written to address:

• Steps, ladders, and handholds on mobile machinery

• Three-points-of-contact principles

• Step spacing, angles, and visibility

• Operator movement during normal and emergency use

ISO 2867 recognises that:

• Access may occur while the machine is dirty or uneven

• Perfect stair geometry is not always achievable

• Human factors and behaviour are central to safety

For many mobile plant applications, ISO 2867 provides a more realistic baseline than fixed plant standards.

ISO 14122 (Safety of machinery – Permanent means of access) is also commonly referenced, particularly for machinery with semi-permanent access platforms or service walkways.

While ISO 14122 offers useful guidance, it still:

• Assumes relatively stable machinery geometry

• Requires interpretation when applied to articulated or mobile equipment

• Does not remove the need for task-specific risk assessment

It is best used as part of a broader safety-in-design approach, rather than as a standalone solution.

Why Standards Still Aren’t Enough

Even when the “right” standard is selected, standards alone do not account for real-world use.

Access incidents on mobile plant often involve:

• Operators jumping or stepping off instead of using designed access

• Hands or feet placed outside intended contact zones

• Access used while carrying tools

• Ingress/egress during maintenance rather than operation

• Use in poor weather or low-light conditions

These are human factors problems, not purely structural ones.

A compliant step that encourages unsafe behaviour is not a safe design.

Safety in Design: The Missing Layer

Effective access system design for mobile plant must include a Safety in Design risk assessment that considers:

• How operators actually approach and leave the machine

• Whether three points of contact can realistically be maintained

• Visibility of steps and handholds from the operator’s perspective

• Likely misuse under time pressure

• Emergency egress scenarios

• Interaction with surrounding plant and structures

This process often results in design decisions that go beyond minimum dimensional compliance, such as:

• Re-positioning access routes

• Adding intermediate steps or handholds

• Improving visual contrast and step definition

• Reducing the need for climbing where possible

Certification vs Safe Access

Certification can confirm that an access system:

• Meets the nominated standard

• Has adequate structural strength

• Is fit for its intended load

But certification alone does not confirm that:

• The access system is intuitive to use

• It discourages unsafe behaviour

• It remains safe across all operating conditions

This is why access system certification must be supported by engineering judgement and safety-in-design thinking.

Trang’s Approach to Mobile Plant Access Systems

Trang Imagineering supports clients with:

• Design and certification of access systems on mobile plant

• Review of existing access arrangements

• Selection and justification of appropriate standards

• Safety-in-design risk assessments

• Practical engineering advice grounded in real operating environments

Our focus is on ensuring access systems are not just compliant, but safe, usable, and defensible.

AS 1657 remains an important standard for fixed plant, but mobile plant requires a different lens. Standards such as ISO 2867 and ISO 14122 are often more appropriate — yet still require careful interpretation and safety-in-design assessment.

Need a Design Review or Certification?

If you’re looking to certify an access system on mobile plant, or want an independent engineering review of an existing design, contact Trang.