United States Department of Part 650 Agriculture Natural Engineering Field Handbook Resources Conservation Service Chapter 1 Surveying Chapter 1 Surveying Part 650 Engineering Field Handbook Issued October 2008 Cover illustration: Roman groma The early Roman surveyors used an instrument called the groma to lay out their cities and roads by right angles. The word “groma” is thought to have come from the root Greek word “gnome,” which is defined as the pointer of a sundial. The importance of turning right angles is shown in the layout of several cities in northern Italy, as well as North Africa. The land was subdi- vided into 2,400 Roman feet square. Each square was called a centuria. The centurias were crossed by road at right angles to each other. The roads that ran north-south were called cardines, and the roads that ran east-west were called decumani. The groma was also used to locate and place monumen- tation for property corners. Once the centurias were in place, maps were drawn on bronze tablets giving a physical representation of the centuria. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, re- prisal, or because all or a part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a com- plaint of discrimination write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795- 3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provid- er and employer. (210–VI–EFH, October 2008) Chapter 1 Surveying Part 650 Engineering Field Handbook Preface This manual is a revision of the Engineering Survey chapter of the 1969 Soil Conservation Services Engineering Field Manual for Conservation Practices. The chapter has been revised with respect to general surveying practices relevant to the NRCS engineering practices and includes new sec- tions on global positioning systems, as well as other newer electronic tech- nologies. In addition, a new section has been added on Public Land Survey Systems (PLSS). Many sections that deal with more outdated technologies or tools have been retained as important to practitioners who may need to understand previous survey procedures and techniques, especially in the case of resurveys. The objective of this chapter is to provide guidance in the use of basic sur- veying principles, techniques, and procedures for the field layout and sur- vey of soil and water conservation projects. The material presented is lim- ited to the types of conservation surveying practices which are used most often. The chapter is intended primarily for use at the field office level. Basic prin- ciples of surveying are essentially the same regardless of the project loca- tion. But, to assure the applicability of the chapter nationally, it was nec- essary to treat certain portions of the text in a more general manner than would have been the case had it been prepared for a specific region or area. This is especially the case with regard to the section on Public Land Survey. Jim Kiser Instructor of Surveying and Land Measurements Department of Forest Engineering College of Forestry, Oregon State University Corvallis, Oregon 97331 (210–VI–EFH, October 2008) 1–i Chapter 1 Surveying Part 650 Engineering Field Handbook 1–ii (210–VI–EFH, October 2008) Chapter 1 Surveying Part 650 Engineering Field Handbook Acknowledgments Development of this manual was guided by the following committee, as- signed by Sam Carlson, P.E., former national construction engineer, Conservation Engineering Division, NRCS, Washington, DC. Dennis Clute P.E., construction engineer, National Design, Construction, and Soil Mechanics Center, NRCS, Fort Worth, Texas H. Grady Adkins, Jr., P.E., former State conservation engineer, NRCS, Columbia, South Carolina Michael Cox, P.E., State conservation engineer, NRCS, Indianapolis, Indiana Brett Nelson, P.E., State conservation engineer, NRCS, Palmer, Alaska Development of the Satellite-based Surveying section of this manual was guided by the following committee, assigned by Noller Herbert, P.E., director, Conservation Engineering Division, NRCS, Washington, DC. Consultation was provided by Mike Rasher, soil conservationist, National Cartography and Geospatial Center, NRCS, Fort Worth, Texas. Keith Admire, P.E., director, National Water Management Center, NRCS, Little Rock, Arkansas Dave Dishman, P.E., State conservation engineer, NRCS, Portland, Oregon Mike Hammitt, civil engineering technician, NRCS, Columbus, Ohio David Nelson, P.E., assistant State conservation engineer, NRCS, Amherst, Massachusetts Chuck Schmitt, P.E., assistant State conservation engineer, NRCS, Casper, Wyoming Tony Stevenson, P.E., agricultural engineer, National Water Management Center, NRCS, Little Rock, Arkansas Nathaniel Todea, P.E., hydraulic engineer, NRCS, Salt Lake, Utah David Williams, P.E., State construction engineer, NRCS, Columbia, Missouri Kenneth Worster, P.E., civil engineer (Design), National Design, Construction, and Soil Mechanics Center, NRCS, Fort Worth, Texas Kip Yasumiishi, P.E., agriculture engineer, West National Technology Support Center, NRCS, Portland, Oregon (210–VI–EFH, October 2008) 1–iii Chapter 1 Surveying Part 650 Engineering Field Handbook 1–iv (210–VI–EFH, October 2008) Chapter 1 Surveying Contents 650.0100 Introduction 1–1 650.0101 Errors in survey measurements 1–1 (a) Random errors ................................................................................................1–1 (b) Systematic errors ...........................................................................................1–1 (c) Blunders ..........................................................................................................1–1 650.0102 Precision and accuracy 1–2 (a) Precision ..........................................................................................................1–2 (b) Accuracy ..........................................................................................................1–2 650.0103 Units of measure 1–4 650.0104 Specialized types of surveys 1–5 650.0105 Field notes 1–5 (a) Other information ...........................................................................................1–6 650.0106 Communication 1–13 (a) Hand signals ..................................................................................................1–13 (b) Radios ............................................................................................................1–13 650.0107 Fundamentals of surveying 1–16 (a) Measurement of dimensions .......................................................................1–16 650.0108 Basic surveying mathematics 1–18 650.0109 Conversion of degrees to decimal equivalents 1–22 650.0110 Basic surveying measurements 1–22 (a) Determining horizontal position ................................................................1–22 (b) Determining horizontal distance ................................................................1–26 (c) Measurement of horizontal distances ........................................................1–26 (d) Determining horizontal angles ....................................................................1–30 (e) Determining direction ..................................................................................1–31 (f) Determining vertical position .....................................................................1–32 (g) Determining vertical distance .....................................................................1–32 (h) Determining vertical angles ........................................................................1–33 (i) Determining vertical coordinate position .................................................1–33 650.0111 Surveying equipment 1–34 (a) Orders of accuracy .......................................................................................1–34 (b) Allowable error in a survey .........................................................................1–34 (c) Instruments that measure horizontal distance .........................................1–35 (d) Instruments that measure horizontal direction ........................................1–37 (e) Instruments that measure vertical distance .............................................1–38 (f) Instruments that measure vertical angle ...................................................1–42 (g) Instruments that measure both horizontal and vertical distance .........1–42 (210–VI–EFH, October 2008) 1–v Chapter 1 Surveying Part 650 Engineering Field Handbook (h) Surveying accessories ..................................................................................1–47 (i) Care and handling of surveying instruments ............................................1–49 (j) Checking and adjusting instruments .........................................................1–50 650.0112 Surveying procedures 1–55 (a) Horizontal survey .........................................................................................1–55 (b) Vertical survey ..............................................................................................1–56