Gate road that is driven simultaneously with the longwall coal face, when the advancing longwall technique is used, but which is maintained some 10 to 20 yd (9 to 18 m) or more in advance of the face. The area immediately ahead of the coal face is therefore preexplored, and steps can be taken to cope with minor disturbances and thus prevent a serious loss of output. Nelson
Source: Dictionary of Mining, Mineral, and Related Terms
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