Uses for plane surveys n Land survey n
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Uses for plane surveys n Land survey n Engineering or construction surveys n Field mapping Top: Plane Table Mapping. M. Denny. www. pobonline. com. . . Bottom: www. tpub. com/engbas/11 -24. htm CS 128/ES 228 - Lecture 10 a 1
Basic methods n Locating a point n Measuring an angle n Measuring a distance n Measuring differences in elevation CS 128/ES 228 - Lecture 10 a 2
Locating a point n Start with known location or previous point n Direction + distance common for plane surveys (ex. “metes & bounds”) n Two angles common for geodesy Principles of Surveying. 2 nd ed. C. A. Herubin, 1978 CS 128/ES 228 - Lecture 10 a 3
Measuring an angle n Horizontal angles: use level, transit, or theodolite n Vertical angle: use transit or theodolite Both: Principles of Surveying. 2 nd ed. C. A. Herubin, 1978 n Either: - graduated circles or - digital readout CS 128/ES 228 - Lecture 10 a 4
Angles: readability n n Horizontal & vertical circles typically graduated to 1 o for construction grade instruments, 5’ or better for survey instruments Vernier improves resolution by 10 x or better Principles of Surveying. 2 nd ed. C. A. Herubin, 1978 § Digital readouts to 5” or better CS 128/ES 228 - Lecture 10 a 5
Measuring a distance n Start with known location or previous point n Three techniques: 1. Taping 2. Stadia markings 3. Electronic distance measurements (EDM) CS 128/ES 228 - Lecture 10 a 6
Taping: errors (& fixes) n Alignment – plumb bob n Tension – tension handle (or experience) n Thermal expansion – correction tables Diagram: www. benmeadows. com n Slope - cosines CS 128/ES 228 - Lecture 10 a 7
