pioneer tunnel
noun
variants
or pioneer bore
: a small tunnel parallel to a main tunnel and well in advance of the completed main tunnel so that by crosscuts to the line of the main tunnel several headings can be exposed and work expedited
Dictionary Entries Near pioneer tunnel
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“Pioneer tunnel.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/pioneer%20tunnel. Accessed 29 Nov. 2024.
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