Communication is an essential part of everyday mine operation. If communication breaks down, the safety of the workers can be put at risk, and lives could be lost. Other than the obvious telecommunications methods, there is is one method that is easily recognizable underground -- the cap lamp signals. At a museum in Alaska, I saw the following exhibit, and explanation:
An up and down motion (nodding) means move away from the source of light.
A circular motion means move towards the source of light.
A side to side motion (horizontal) means stop!
"Most accident investigations have indicated that poor communication, or a break down in communication often contributed to the accident."
