Tag Archive for Tag: Surveying

Tag: Surveying Surveying Worked example in setting out

The purpose of conducting a traverse of the type described in Appendix E would typically be to establish additional local control points, in order to set out specified points for construction work. Suppose now that it is required to set out a foundation point X at the co-ordinates (544,850.000E, 257,200.000N) to high accuracy. The accepted co-ordinates of the nearby stations

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Tag: Surveying Surveying Worked examples in adjustment

E.1 Bowditch adjustment This example shows how the Bowditch calculation sheet, introduced in Chapter 10, is used in a simple traverse to fix the positions of two unknown points (C and D, in Figure E.1). The scheme of observations is as shown in Figure E.1, with stations A, B, E and F having known co-ordinates. Note that this is not

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Tag: Surveying Glossary of Surveying

Alidade bubble The bubble (usually a split bubble) used to set the vertical circle, usually so that the zero degree marker is pointing directly upwards. Backlash The looseness or ‘play’ in a piece of mechanism which means that not all parts of the mechanism are always in the same place when one part of it is moved to a particular

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Tag: Surveying Calculation of local scale factors in transverse Mercator projections

D.1 Quick calculation The ‘quick’ formula for calculating a scale factor is: where S0 is the central scale factor, E0 the false easting of the true origin and RE the mean radius of the earth. This formula is accurate to 2 parts per million at all places within 200 km of the central meridian, and to 50 parts per million

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Tag: Surveying Surveying Worked example in transforming between ellipsoids

This example shows how the geographical co-ordinates of a station can be converted from one system to another, following the method given in Section 8.4. In this case, the initial co-ordinates are quoted in the ETRS89 system, so are based on the WGS84 ellipsoid; and they are to be converted to the Airy ellipsoid, whose position and orientation was defined

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Tag: Surveying Surveying Appendix B

Control stations B.1 What is a control station? The essence of a control station is a small mark set immovably into the ground, such that an instrument (e.g. a total station or GPS receiver) or optical target can be set up above it, to an accuracy of about 1 mm in the horizontal plane. B.2 Where are they placed? Control

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Tag: Surveying Satellite surveying

7.1 Introduction At the time of going to press, satellite surveying relies mainly on a system called global positioning system (GPS), which was originally set up as a military navigation aid by the USA in the mid-1980s, but which has now become a significant tool for civilian use in general and surveyors in particular. Using so-called differential GPS (DGPS), in

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Tag: Surveying Principal surveying activities

3.1 Managing control networks Before any survey can yield useful results, it is necessary to establish a set of fixed stations whose positions relative to one another are known—usually to a higher accuracy than will be needed in the final result. A set of such stations is known as a control network. If the scope of an engineering project is

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Tag: Surveying General principles of surveying

Surveying has two notable characteristics: the work is done to a much higher level of accuracy than most other engineering work and it is easy for quite serious errors to remain undetected until it is too late to correct them. For this reason, there are some inherent principles which should be observed in all surveying, regardless of the type of

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