A mobile plant operative parked a fully loaded CAT 775 rigid dump truck in the designated mobile plant parking area before going for his break. Several minutes later the unattended machine began to roll forward, gaining speed, before crossing a haul road, hitting a section of edge protection bund and overturning. No one was hurt and no other plant or vehicles were involved.

A review of the incident established the following facts;

• On inspection, post-incident, the parking brake was found to be in the “OFF” position.
• CAT 775 D-models have a manual “ON/OFF” parking brake switch. On newer models the parking brake is failsafe and automatically applied when the machine engine is switched off.
• The truck operator was fully trained, experienced, and familiar with the controls of the machine.
• The mobile plant parking bays had been built on a slight forward-facing slope.
• The operator and passenger had climbed from the access steps at the front of the machine.

1. Machines should always be parked on flat level ground, or a slight front-to-rear incline with bund behind.

2. Machines parked on open gradients, where they could roll away, should always be wheel chocked.

3. Operators must ensure the parking brake is properly applied before they get out of the machine.

Site managers should check for any machines with manually operated parking brakes and where possible retrofit an audible warning device to alert the driver if he/she attempts to get out of the machine if the brake has not been applied.

If discussing or reviewing this incident with colleagues a good question to ask is - Could a similar incident happen on our site and if so, what are we going to do to make sure it doesn’t?