Excavator rolls over on 1:3 batter

Background

A contract arborist was using an excavator with a log grab attachment to move felled trees down a batter.

While slewing the excavator down slope, a log slipped through the 'log grabber' attachment pulling on the excavator's boom. The combination of slewing while tracking and the unexpected slip of the log caused the excavator's centre of gravity to suddenly move, rolling onto its side.

The operator was wearing a seatbelt and received facial injuries and was admitted to a local hospital for treatment.

Safety issues

Hazards that may pose a risk to employee health and safety when operating excavators on batters and/or slopes include:

• Traversing across a slope or turning on a slope can reduce the excavator's stability, causing it to overturn.
• Carrying an elevated load while working on a slope can raise the centre of gravity of the plant, increasing the likelihood of the plant overturning.
• Slippery or low traction surfaces can cause the excavator to skid, lose control or run away.
• Uneven, soft or unconsolidated ground can cause the excavator to rock, lose control or overturn.

Recommended ways to eliminate or reduce the risks

The risks associated with operating mobile plant on slopes including batters can be eliminated by moving the plant off the slope using an alternative system of work, for example:

• using a haul rope or winch cable fitted to mobile plant that is positioned on the flat level ground at the bottom of the slope to drag the felled trees down the batter/slope

If it is not reasonably practicable to eliminate the use of mobile plant on a batter/slope, employers can reduce the risk of mobile plant overturning by:

• assessing the angle of the batter/slope to ensure that the excavator can safely ascend and descend without overturning. If limitations are not provided by the manufacturer, operators should approach the slope from the bottom to confirm the mobile plant's capability of ascending the slope without overturning and/or running away down a slope
• ensuring plant, including excavators, only ascend and descend the slope with the arm of the excavator extended up the slope
• ensuring that any load carried by the attachment is placed as low to the ground as possible
• ensuring that rollover protection structures (ROPS) are installed on mobile plant and that operators wear a seatbelt
• using handheld tools to reduce the size of items being moved on the slope

Consult with employees and independent contractors

Employers must consult with employees and independent contractors when identifying, assessing and controlling risks. Employees and independent contractors can provide important information about what risks look like in their work. Employees independent contractors with a broad range of expertise should be consulted. This will ensure all aspects of risk are considered.

Legal duties

Employers have duties under the Occupational Health and Safety Act 2004. They must, so far as is reasonably practicable:

• provide and maintain a working environment that is safe and without risks to the health of employees and independent contractors and their employees
• provide and maintain plant or systems of work that is safe and without risks to the health of employees and independent contractors and their employees
• consult with employees, independent contractors and their employees, and health and safety representatives when identifying or assessing hazards or risks and making decisions about risk control measures
• ensure that persons other than employees are not exposed to risks to their health or safety arising from the conduct of the employer's undertaking

Employers must also provide employees and independent contractors and their employees with the necessary information, instruction, training or supervision to enable them to do their work in a way that is safe and without risks to health.

Under the Occupational Health and Safety Regulations 2017, employers and self-employed persons must, so far as is reasonably practicable:

• identify all hazards associated with the use of plant at the workplace
• control risks associated with plant in accordance with the plant hierarchy of control
• ensure the plant is inspected to the extent necessary to ensure that risks associated with its use are monitored