Underground Traffic System Improves Mine Safety

You're driving a large vehicle down a steep, single-lane, pitch-black tunnel. Visibility through the wet, grimy windows is nearly nonexistent. Communication on the two-way radio is garbled. Then, around the corner — a flicker of lights. There's no accessible turn-off, no time to back up. And a 50-ton truck is heading straight toward you.

Just another day at the office for workers at BHP Billiton's underground Cannington Mine, the world's largest and lowest cost producer of silver and lead. Located in northwest Queensland, Australia, Cannington has reported incidents and accidents on the descent leading into the mine, including collisions and near-misses — both man/machine and machine/machine. These events initiated the search for a solution that would minimize the risks of operating mobile equipment in the underground environment.

"Like a corkscrew in a tunnel, a vehicle coming around the corner is not visible until it's pretty much right on top of you," explains Daniel Russell, Cannington project engineer. In order for equipment operators to keep track of the location of other vehicles, "we needed to increase the information to our drivers."

Taking the wheel

Committed to improving their safety record, Cannington turned to CSC for an underground traffic management system. Adding to the challenge was the requirement that it be nonintrusive and easily accepted by the drivers themselves — a group not particularly comfortable with either technology or unfamiliar processes. One of the first hurdles to overcome, according to CSC System Architect, Solution Designer and Project Manager Kobus Du Plessis, was befriending the drivers and understanding their working environment.

"From an engineering point of view, forget about academics," says Du Plessis.

He has been involved with the project since it began in June 2004 — analyzing the problem, designing the concept solution, developing the final design, even installing the physical equipment in the walls. "The most important thing is to experience the problem and see how difficult it is for them." To that end, Du Plessis obtained an underground driver's license. "It’s not easy driving down a hole into the ground with 50-ton trucks coming toward you," he says. "But if you don't know what they're experiencing, you're not going to get it right."

Tagging each vehicle

After thoroughly assessing the situation, Du Plessis designed a solution using Radio Frequency Identification (RFID) technology to manage the traffic movement — the first time this technology has been operational underground. Installed on the roof of every vehicle is an active RFID tag, continuously sending out signals marking that vehicle's real-time whereabouts. Those signals are then picked up by RFID readers and displayed on LCD screens installed in numerous strategic places throughout the tunnels, They allow drivers to see approaching vehicles — type, position and direction — from three to four levels down.

Since it's much more difficult for loaded trucks returning to the surface to start up again after stopping, they have the right of way over empty trucks descending into the mine. Seeing in real-time where other trucks are heading allows drivers ample time to pull onto a turnout and let the ascending vehicle pass. "It's a noncomplicated solution with a huge impact," says Du Plessis. "We're helping the guys to make decisions, to be more proactive."

As part of a three-month pilot system, Du Plessis installed the solution in three zones within the mine. "Kobus discovered that the tags being used didn’t have the level of fidelity to do the job," says Jeremy Davies, CSC account executive. "There were misreadings and missed signals."

Under Du Plessis' direction, the project's technology vendor — Germany-based Becker — made significant changes, refining the algorithms and developing new tags and readers specifically for this project. "Once the system is in place, people become secure and rely on it," says Davies. "So it's absolutely mission critical that these systems operate 100 percent."

Improving safety and productivity

Next up was a major production demonstration, which took place in a 14-zone section, covering a length of six kilometers (3.7 miles) and descending 90 meters into the 605-meter mine. Included in this 14-zone area is the main entrance through which all vehicles must pass, making this the mine's busiest area. A corrugated iron tunnel built on 30 to 40 meters of soil, this tube acts as a portal into the mine's hard rock.

Challenges continued even after the system was installed. "We had an issue with voltage drop on the displays, so we had to replace the screens," remembers Russell. And, there were two periods of three months each when the entire system had to be removed in order to rehabilitate the tunnels with steel grids.

Since the system was installed in February 2007, there have been no accidents or incidents in that 14-zone area. The RFID technology also provides vehicle movement data that can be used to improve productivity, enabling production managers to keep track of underground equipment movement and performance. And, as an added benefit, drivers' confidence levels are much higher now that they're able to react early enough to avoid potential accidents. "I certainly feel more relaxed being able to see if there's a load coming toward me," says Russell. "I think we've achieved what we set out to do."

For his work on the underground traffic management system, Du Plessis received a CSC Chairman's Award for Excellence, the most prestigious honor for CSC employees.

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