Xstrata Alloys develops leading practice collision avoidance system

Xstrata Alloys and Becker Electronics have developed leading practice technology for safely managing the interaction of vehicles and pedestrians in underground mines, with total investment of ZAR6.4 million.

This technology was developed in response to the identification of interaction between vehicles and employees underground as one of the principal causes of critical incidents at Xstrata Alloys operations. The findings from high potential risk incidents and the investigation into a fatal incident involving a load haul dump (LHD) operator in October 2004 were used to determine the requirements for a technology to manage this risk. The primary purpose of the technology is to improve the visibility of equipment and employees underground and ensure early detection and warning for vehicle operators and pedestrians using the same area. This is achieved through the transmission of radio signals between vehicles and individuals' headgear, which causes head lamps to flash and give audible alarms when vehicles are in proximity or approaching.

A small technical team comprising Xstrata and Becker personnel was established to adapt a prototype being used in Indonesian open cut mines to the harsher underground environment and to test whether the chrome seams would affect the radio signal. Xstrata Alloys specified the product application and Becker developed the software and hardware.

Two initial trials of the technology confirmed the principle behind the technology would work, but did not meet performance requirements for robustness or performance in an underground environment. On the third attempt, new technology from Becker – the CAS300 vehicle transmitting unit – was adopted and was found to address the issues encountered in previous trials. An industrial antenna was installed to the vehicle/equipment transmitting unit and the unit was made waterproof to cope with high pressure cleaning. The new system was fitted to 125 vehicles and 1600 personnel avoidance system (PAS) receiver tags were distributed to employees across five chrome operations.

Roy Murley, Xstrata Alloys Mining Division Engineering Manager said that, 16 months later, the system was working well despite some minor vibration issues and had been well accepted by pedestrians and operators.

"This system has demonstrably improved safety. The interaction between vehicle and pedestrian has been made more obvious and people are definitely changing their behaviour. In the past, the guys would walk beside a machine. Now, when they receive a PAS warning, they stand aside and wait for the vehicle to go past before continuing on," he said.

To further extend the application of the people and vehicle detection system, Xstrata Alloys has introduced a lamp room control system. Every employee who goes underground has a designated cap lamp, rescue pack and monitoring equipment stored in the lamp room on the surface of the mine. As part of the new system, an electronic reader has been installed in every lamp room.

As an employee passes the reader before going through the turnstile, a warning sounds and a message is displayed on an electronic billboard if the cap lamp is not fully charged, equipment like methanometers are not correctly calibrated or the employee is not carrying the correct equipment. In phase two of this project, the system will be interlocked with the turnstile preventing the employee from going underground until the problem identified by the reader has been rectified.

"If the lamps are not fully charged, they emit a dim light which makes it difficult for operators to see pedestrians," he said.

"My observation is that there are now very few incidences of faulty lamps underground and that this new culture is starting to be embedded."