Syrveying Using Total Station
NIO/TR - 4 /2007
A METHOD OF TRANSFERRING G.T.S. BENCHMARK VALUE TO SURVEY AREA USING ELECTRONIC TOTAL STATION
GANESAN, P.
DECEMBER 2007
NATIONAL INSTITUTE OF OCEANOGRAPHY
REGIONAL CENTRE, VISAKHAPATNAM. INDIA
1
TABLE OF CONTENTS
ABSTRACT INTRODUCTION EQUIPMENT USED METHOD OF SURVEY PERMISSIBLE ERROR LIMITS PRECAUTIONS TAKEN RESULTS AND CONCLUSION ACKNOWLEDGEMENT REFERENCES LIST OF TABLES AND FIGURES
2
A METHOD OF TRANSFERRING G.T.S. BENCHMARK VALUE TO SURVEY AREA USING ELECTRONIC TOTAL STATION
GANESAN, P. ( National Inst. Of Oceanography, Regional Centre, Visakhapatnam. ) (Email: ganeshan@nio.org Phone:0891-2539180) (Keywords: G.T.S. Benchmark, Mean sea level, Chart datum. Tide pole, Inter-tidal zone)
ABSTRACT
A G.T.S. (Great Trigonometrical Survey) benchmark is a permanently fixed reference survey station (or point), having known elevation with respect to a standard datum (mean sea level). These are established all over India by Survey of India department with greater precision. A benchmark value is quite essential at any survey area, especially for reduction of observed sea level with respect to mean sea level or chart datum (CD). While carrying out bathymetric survey of a survey area, the datum referenced values thus obtained are used to compute the final depth contours of the survey area (with respect to CD). So, a benchmark, having known elevation is quite essential at the survey area, without which, preparation of a bathymetric chart is impossible. In some places, GTS benchmarks are available within a kilometer distance and can be easily transferred to the survey area by fly leveling using an automatic Level instrument and a graduated leveling staff. But in most of the cases, GTS benchmarks may be at far away distance from the area to be surveyed. In these cases, the most common traditional method of transferring the benchmark value using an automatic level instrument is a difficult task, consuming enormous amount of time and
A METHOD OF TRANSFERRING G.T.S. BENCHMARK VALUE TO SURVEY AREA USING ELECTRONIC TOTAL STATION
GANESAN, P.
DECEMBER 2007
NATIONAL INSTITUTE OF OCEANOGRAPHY
REGIONAL CENTRE, VISAKHAPATNAM. INDIA
1
TABLE OF CONTENTS
ABSTRACT INTRODUCTION EQUIPMENT USED METHOD OF SURVEY PERMISSIBLE ERROR LIMITS PRECAUTIONS TAKEN RESULTS AND CONCLUSION ACKNOWLEDGEMENT REFERENCES LIST OF TABLES AND FIGURES
2
A METHOD OF TRANSFERRING G.T.S. BENCHMARK VALUE TO SURVEY AREA USING ELECTRONIC TOTAL STATION
GANESAN, P. ( National Inst. Of Oceanography, Regional Centre, Visakhapatnam. ) (Email: ganeshan@nio.org Phone:0891-2539180) (Keywords: G.T.S. Benchmark, Mean sea level, Chart datum. Tide pole, Inter-tidal zone)
ABSTRACT
A G.T.S. (Great Trigonometrical Survey) benchmark is a permanently fixed reference survey station (or point), having known elevation with respect to a standard datum (mean sea level). These are established all over India by Survey of India department with greater precision. A benchmark value is quite essential at any survey area, especially for reduction of observed sea level with respect to mean sea level or chart datum (CD). While carrying out bathymetric survey of a survey area, the datum referenced values thus obtained are used to compute the final depth contours of the survey area (with respect to CD). So, a benchmark, having known elevation is quite essential at the survey area, without which, preparation of a bathymetric chart is impossible. In some places, GTS benchmarks are available within a kilometer distance and can be easily transferred to the survey area by fly leveling using an automatic Level instrument and a graduated leveling staff. But in most of the cases, GTS benchmarks may be at far away distance from the area to be surveyed. In these cases, the most common traditional method of transferring the benchmark value using an automatic level instrument is a difficult task, consuming enormous amount of time and
References: 1. Ganesan, P. 2003. Delineation of high tide line using DGPS and laser trak instruments: With special reference to mapping techniques. NIO/TR/5/2003; 2003; 20 pp. 2. Kanetkar, T.P. 2006. Surveying and Leveling; Volume I & II.