Decision trees and the rescue of the Chilean miners

As the world celebrates with Chile following the rescue of the 33 miners trapped underground for 69 days, it is interesting to review the various technologies that have been instrumental in supporting the engineering feat that lifted the men to ground level.

For example, during the crisis, mining expert Manuel Viera, the CEO and managing partner of engineering consultancy and Palisade partner, Metaproject, proposed a model to determine the rescue method that would subject the miners to the least risk.  He used Palisade’s decision tree analysis tool, PrecisionTree, to evaluate the various alternatives from a technical and economical perspective.

The decision evaluation challenge was how to rescue the miners as quickly as possible, as well as ensure that their mental and physical health was maintained while the rescue mission was planned and implemented.  The rescue operation was very risky, not least because it was possible that another landslide could occur, with causal factors including geological faults, lack of accurate information from the plans of the inside of the mine, and insufficient knowledge about the structural geology of the mine. The additional drilling required to rescue the miners could have caused walls to collapse further as a result of micro fractures and faults in the rock.

A key decision in the risk analysis was whether to raise the miners to 300 meters below the surface, or to keep them in their current location near the refuge at 700 meters.  There were also several drilling options for reaching the trapped miners.
 
PrecisionTree presented a matrix of statistical analysis results for each branch tree (i.e. rescue option).  This made it is possible to ascertain, for example, that for some of the drilling options it was feasible to move the miners in two stages, but for others it was not, due to logistical problems. Information such as this is invaluable when decision making under uncertainty is a matter of life and death. 

The actual rescue operation went straight to 700 meters and used three drills at the same time: Drill A, the Strata 950 raise bore machine; Drill B, the Schramm T-130 machine; and Drill C, the RIG 442 machine.  As predicted by the Metaproject PrecisionTree analysis, Drill B was the first to reach the miners.

» Read more about the PrecisionTree model

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