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In the case of roads or other linear infrastructure, a chainage (derived from Gunter's Chain - 1 chain is equal to 66 feet or 100 links) will be established, often to correspond with the centre line of the road or pipeline. During construction, structures would then be located in terms of chainage, offset and elevation.
Offset. Offset is the perpendicular distance between the axes of hypoid gears or offset face gears. [1] In the adjacent diagram, (a) and (b) are referred to as having an offset below center, while those in (c) and (d) have an offset above center. In determining the direction of offset, it is customary to look at the gear with the pinion at the ...
A quarter chain, or 25 links, measures 16 feet 6 inches (5.03 m) and thus measures a rod (or pole). Ten chains measure a furlong and 80 chains measure a statute mile. [1] Gunter's chain reconciled two seemingly incompatible systems: the traditional English land measurements, based on the number four, and decimals based on the number 10.
The Abney level is an easy to use, relatively inexpensive, and, when used correctly, an accurate surveying tool. Abney levels typically include scales graduated in measure degrees of arc, percent grade, and in topographic Abney levels, grade in feet per surveyor's chain, and chainage correction.
Traverse networks involve placing survey stations along a line or path of travel, and then using the previously surveyed points as a base for observing the next point. Connected survey lines form the framework and the directions and lengths of the survey lines are measured with an angle measuring instrument and tape or chain. [2]
Ranging rods of greater length, e.g. 3 to 6 m, are called ranging or range poles, and are used for very long survey lines. [3] Another type of ranging rod is known as an offset rod, which has no flag at the top. It is used for measuring small offsets from the survey line when the work is of an ordinary nature. [4]
What is often referred to as "adequate questionnaire construction" is critical to the success of a survey. Inappropriate questions, incorrect ordering of questions, incorrect scaling, or a bad questionnaire format can make the survey results valueless, as they may not accurately reflect the views and opinions of the participants.
Modern seismic reflection surveys are designed and acquired in such a way that the same point on the subsurface is sampled multiple times, with each sample having a different source and receiver location. The seismic data is then carefully processed to preserve seismic amplitudes and accurately determine the spatial coordinates of each sample.