Autonomous trucks were hauling mine waste on night shift at an open pit mine. The control room operator directed an autonomous haul truck to turn right at an intersection and perform a loop so it could be positioned under an excavator bucket on the pit floor. The intersection and turnaround loop existed in the control system but the intersection was not physically signposted or marked on the
ground to alert manually operated vehicles.
A manned water cart was travelling in the opposite direction when the autonomous truck was about to turn to right. The water cart driver was not aware of the autonomous truck’s assigned path and, on recognising it, tried to take evasive action. The two vehicles collided, resulting in significant damage to the autonomous truck. The water cart driver received minor injuries.
Direct causes
- The travel paths of the autonomous truck and water cart intersected.
- The turnaround loop for the autonomous truck was released for use in the control system but the corresponding intersection was not delineated on the ground, nor its intended use communicated.
- On detecting the water cart in its assigned path of travel, the autonomous truck’s speed (about 40 km/hr) and response time meant it could not prevent the collision.
Contributory causes
- The change management processes for planning and assigning roads in the control system were inadequate.
- An awareness system was set up in the water cart to allow the driver to monitor the autonomous truck’s path. However, at the time of the collision, the water cart driver was not fully aware of the intended path of the autonomous truck.