Excavator Risk Assessment for Australian Workplaces

An excavator risk assessment is a structured evaluation of the hazards and risks associated with the use of hydraulic excavators — including mini excavators (zero tail-swing and standard), medium excavators, and large excavators — in construction, civil works, demolition, mining, and site preparation activities. It identifies the specific hazards created by the machine's size, reach, swing arc, and lifting capacity; the hazards specific to the excavation task being performed (underground services, unstable ground, proximity to structures); and the controls necessary to protect the operator, ground workers, and the public from harm.

Excavators are among the most powerful and hazardous pieces of plant on Australian construction and civil works sites. They can exert bucket forces exceeding 100 kN and can deliver fatal injuries to any person struck by the bucket, boom, or swinging counterweight within seconds. Incidents involving excavators consistently appear in the annual fatality statistics published by Safe Work Australia, with the principal mechanisms being: struck by the bucket or swinging counterweight (often when the operator was unaware of the presence of a ground worker in the swing arc); contact with overhead or underground services; excavation wall collapse; and overturning on unstable ground or slopes.

The WHS Regulation 2025 requires a risk assessment before any work with an excavator, and a Safe Work Method Statement (SWMS) when the excavator is used on a construction site for high-risk construction work — specifically, work involving excavation or trenching to a depth of more than 1.5 metres. For most construction site excavator operations, a SWMS is mandatory. Off-site, on commercial or rural properties, and in mining contexts, the risk assessment format may differ from the SWMS but the obligation to assess and control the risks is unchanged.

An excavator risk assessment must address not only the general risks of operating a hydraulic excavator but the site-specific and task-specific hazards that make each excavator operation unique: the underground services present, the proximity to structures and boundaries, the presence of overhead lines, the stability of the ground, and the specific work to be performed.

The legal framework governing excavator operations in Australia combines general WHS obligations with specific requirements for plant licensing, operator competency, underground service detection, and high-risk construction work.

**WHS Regulation 2025 — Plant:** The WHS Regulation imposes specific duties on persons who manage or control plant — including excavators — at a workplace. These include ensuring the plant is designed, manufactured, supplied, and installed correctly; that it is inspected and maintained in accordance with the manufacturer's requirements; that it is registered if it meets the registration thresholds in Schedule 5 of the Regulation; and that workers operating the plant are competent to do so.

**High-risk work licensing — excavators:** Excavators over 3 tonnes rated operating mass require a high-risk work licence for earthmoving machinery — specifically the 'Basic excavator' licence class under the WHS Regulation. The risk assessment must verify that the excavator operator holds the appropriate licence class for the specific machine being operated. Operators of mini excavators under 3 tonnes do not require a high-risk work licence, but must still be trained and assessed as competent by the PCBU.

**SWMS for high-risk construction work:** On construction sites, excavator use for trenching or excavation to a depth of more than 1.5 metres is high-risk construction work under Schedule 1 of the WHS Regulation. A SWMS is mandatory. The SWMS must identify the specific hazards of the excavation task, specify the controls, and be signed by each worker performing the work.

**Underground service requirements:** Working near underground services — gas, water, sewer, telecommunications, electricity — requires compliance with the 'Dial Before You Dig' referral system (1100 or dialbeforeyoudig.com.au) and with the Safe Excavation and Trenching Code of Practice. Before any excavation, the PCBU must obtain service plans from the relevant utility owners, locate and mark the service routes using electronic detection equipment, and expose services using non-destructive means (vacuum excavation, hand digging) within the exclusion zone (0.3–0.5 m either side of the marked route, depending on the service type) before excavating with mechanical equipment.

**Overhead electrical lines:** Work with excavators near overhead electrical lines requires specific controls under the relevant electrical safety legislation (NSW: Electrical Safety Act; Qld: Electrical Safety Act 2002; Vic: Electrical Safety Act 1998). The plant must not approach within the minimum safe approach distance (MSAD) — which varies by voltage — unless the line has been de-energised and earthed, or the plant operator is supervised by an authorised high-voltage approach worker.

A comprehensive excavator risk assessment must address five principal hazard categories.

**Collision with personnel.** The most catastrophic excavator incidents involve ground workers being struck by the machine's moving parts — the bucket, boom, stick, or counterweight — while within the swing arc or in the track path. The swing arc of a standard excavator covers 360 degrees, and the counterweight extends significantly beyond the machine's tracks. Ground workers who are not visible to the operator through mirrors or cameras, or who enter the exclusion zone without the operator's awareness, are at extreme risk. Controls include: a defined exclusion zone around the machine; a trained spotter when ground workers must work near the machine; physical barriers; and two-way communication between the operator and ground workers.

**Contact with underground services.** Striking a live underground electrical cable with an excavator bucket can result in electrocution of the operator (through voltage gradient in the ground) and of ground workers in contact with the machine or within the voltage gradient zone. Striking a gas main can cause a gas release and subsequent fire or explosion. The risk assessment must specify the pre-excavation service search and location requirements, the exclusion zone from marked services, and the procedure for exposing services using vacuum excavation or hand digging before mechanical excavation.

**Contact with overhead electrical lines.** Excavator booms — particularly those of larger machines — can reach considerable heights and can contact overhead power lines during normal operations if the work area is not properly assessed and controlled. The risk assessment must identify all overhead lines in and near the work area, their voltage and clearance heights, and the controls required to prevent contact.

**Excavation collapse.** Trench and excavation wall collapse can trap workers who are working in or near the excavation. The risk assessment must evaluate the soil type, groundwater conditions, depth of excavation, proximity of surcharge loads, and the battering, benching, or shoring required to stabilise the excavation walls. AS 4744.1 provides guidance on trench shoring requirements.

**Machine instability and overturning.** Excavators can overturn when operating on soft, sloping, or undermined ground, when lifting loads beyond their rated capacity, or when operating with the boom in an over-extended position. The risk assessment must evaluate the ground bearing capacity at the machine's working positions, the slope gradient, and whether the lift calculations confirm the planned lifts are within the machine's rated capacity at the relevant working radius.

A compliant excavator risk assessment follows the WHS risk management methodology, with steps specific to plant hazards.

**Step 1 — Pre-site assessment.** Before mobilising the excavator to site, review the site survey or geotechnical report for ground conditions, obtain underground service plans from Dial Before You Dig, identify overhead electrical lines from the electricity network provider's system maps, and assess access routes for machine delivery. Confirm that the excavator selected is appropriate for the task — the required reach, digging depth, bucket size, and lifting capacity — and that the machine is registered, inspected, and in serviceable condition.

**Step 2 — Site assessment on arrival.** Walk the work area with the excavator operator before operations commence. Identify and mark the location of underground services. Mark the exclusion zone around the swing arc of the machine. Identify the overhead line hazard areas and confirm clearances. Assess the ground conditions at each proposed operating position. Brief all ground workers on the exclusion zone, the communication system, and the stop-work signal.

**Step 3 — Assess the risks.** For each hazard identified, assess the likelihood and consequence using a risk matrix. Struck-by and excavation collapse hazards typically rate as extreme or high, given the potential for fatality or serious injury, which requires immediate implementation of strong controls.

**Step 4 — Select and implement controls.** Apply the hierarchy of controls: eliminate the need for ground workers within the swing arc (separate phasing of machine and manual work); use physical barriers to define the exclusion zone; implement administrative controls (spotter for proximity work, verbal or hand signals, two-way radio); provide training to all persons involved in the operation. Confirm controls are in place before operating.

**Step 5 — Monitor during operations.** The operator must conduct a visual check of the exclusion zone before each swing or track movement. Where a spotter is required, the spotter must maintain visual contact with all ground workers and with the machine operator throughout the operation. The risk assessment must be reviewed and the pre-start check repeated whenever a new ground worker enters the work area, when the machine moves to a new position, or when conditions change.

**Step 6 — Document and retain.** Record the risk assessment, the pre-start check results, and the SWMS sign-offs in the site safety file. Retain for five years after the completion of the construction project.

The use of a trained spotter — a worker positioned to guide the excavator operator and manage ground worker access near the machine — is one of the most important controls for excavator safety in congested work environments. Understanding when a spotter is required, what the spotter's role is, and the limitations of the spotter role is essential for an effective excavator risk assessment.

**When is a spotter required?** A spotter is required whenever ground workers are working in proximity to an operating excavator and cannot be kept entirely outside the exclusion zone by physical barriers — for example, during manual trimming of excavated surfaces, concrete pouring near an operating excavator, service installation in a trench that the excavator continues to extend, or any operation where the work task requires people to be near the machine's swing arc.

**Spotter qualifications and training.** A spotter for excavator operations must be trained in: the specific machine's swing arc, reach, and blind spots; the two-way communication signals or radio protocol with the operator; the stop-work signal and the authority to use it; and the exclusion zone dimensions and the permitted access conditions. The spotter must be visible to the operator at all times and must not perform any other tasks while serving as spotter.

**Communication between operator and spotter.** The primary communication method between the excavator operator and the spotter must be agreed before operations commence and documented in the risk assessment. Options include: standard hand signals (AS 2550.15 provides standardised signals for earthmoving equipment operations); radio communication (both operator and spotter equipped with two-way radios); and whistle signals (with the stop-work signal being the most important). The stop-work signal must be immediately understood by the operator and must result in the machine stopping within one machine cycle.

**Spotter limitations.** A spotter is an administrative control — it relies on human vigilance and communication to prevent incidents. Research on excavator incidents has shown that human error by either the operator or the spotter is the most common contributing factor in struck-by incidents. The spotter control is therefore less reliable than a physical exclusion barrier and should not be used as the primary control where a physical barrier is practicable.

Our consultant-drafted excavator risk assessment is priced at $49 AUD and is delivered as a fully editable Microsoft Word document within one business day of purchase. The document includes the following sections.

**Pre-site assessment checklist:** Underground service search (Dial Before You Dig), overhead line identification, geotechnical assessment, plant registration and inspection record, and operator licence verification.

**Site assessment form:** Exclusion zone dimensions, spotter requirements, underground service marking record, overhead line clearance confirmation, ground condition assessment, and slope gradient check.

**Hazard identification table:** Each of the five principal hazard categories (collision with personnel, underground services, overhead lines, excavation collapse, machine instability), with sub-hazards specific to the task type.

**Risk matrix:** Likelihood and consequence ratings for each hazard, before and after controls.

**Control register:** Controls in hierarchy order for each hazard, with the responsible person, implementation date, and verification method.

**SWMS integration section:** Where the excavator work is on a construction site and constitutes high-risk construction work, a SWMS reference table linking the risk assessment controls to the relevant SWMS sections.

**Pre-start check record:** A daily pre-start check form for the excavator operator, covering machine inspection (oil levels, tyres, tracks, controls, ROPS/FOPS), site conditions, and exclusion zone verification.

**Operator sign-off:** Operator and supervisor signatures confirming the assessment has been read, understood, and controls are in place.

All documents are reviewed annually for compliance with the current WHS Regulation and applicable Australian Standards.

**Do I need a high-risk work licence to operate a mini excavator?** Excavators with a rated operating mass below 3 tonnes do not require a high-risk work licence under the WHS Regulation. However, the PCBU must ensure that any person operating the mini excavator is competent to do so — meaning they have been trained and assessed as having the knowledge and skills to operate the machine safely. For excavators 3 tonnes and above, the high-risk work licence for earthmoving machinery (excavator class) is required.

**What is the exclusion zone for an excavator?** The exclusion zone should be at minimum the maximum reach of the machine from the operator's cab — encompassing the full 360-degree swing arc including the counterweight. Many PCBUs and principal contractors add a buffer (typically 1–2 metres) beyond the maximum reach. The exclusion zone must be clearly marked with physical barriers or with high-visibility indicators, and workers must not enter without the operator's express permission and with the machine temporarily shut down or controlled.

**Is Dial Before You Dig legally required?** The WHS Regulation requires PCBUs to identify underground services before excavation and to implement controls to prevent contact. While the Regulation does not specifically mandate Dial Before You Dig by name, using the DBYD referral system is the recognised mechanism for obtaining utility service plans, and a PCBU that excavates without obtaining DBYD plans would have difficulty demonstrating that it met the regulatory standard in the event of a service strike incident. Using DBYD is also required under many contract conditions and by utility network operators as a condition of working near their assets.

**Can I excavate near an underground gas main with an excavator?** Only after locating the gas main using non-destructive means (vacuum excavation or hand digging) and confirming its position. The Safe Excavation and Trenching Code of Practice specifies exclusion zones around different service types. For gas mains, mechanical excavation is generally not permitted within 0.5 metres of the marked service route until the service has been exposed and its exact position confirmed. Contact your gas network operator for specific working near gas infrastructure requirements.

**What documentation do I need to keep for excavator work on a construction site?** For a construction site, the SWMS for excavation work, the risk assessment, the pre-start check records, the operator licence record, the Dial Before You Dig reference number and service plans, and any spotter briefing records must be retained in the site safety file for five years after completion of the construction project.