The name Bertha, after Seattle's first female mayor, , was chosen by a panel (that included the Governor and Transportation Secretary) from 150 submissions from kindergarten through 12th graders, who were asked to submit female names with Washington state heritage. The winning entry, which was submitted by two elementary schools in and , was selected in December 2012.
[pdf] The was developed by Sir to excavate the in 1825. However, this was only the invention of the shield concept and did not involve the construction of a complete tunnel boring machine, the digging still having to be accomplished by the then standard excavation methods.
[pdf] Drilling is a cutting process that involves the use of a drill bit to cut a circular-shape hole in a workpiece. The drill bit used in drilling is a type of rotary cutting tool that, like other rotary cutting tools, rotates while subsequently scraping material out of the workpiece. To drill a workpiece, a manufacturing company must. .
Boring is a cutting process that involves the use of a single-point cutting tool or boring head to enlarge an existing hole in a workpiece. This is. .
Finally, reaming is a cutting process that involves the use of a rotary cutting tool to create smooth interior walls in an existing hole in a workpiece. The rotary cutting tool used in reaming is.
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