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Construction Surveying & Layout Published by: BNi Building News A practical guide to simplified construction surveying. How to divide land, use a transit and tape to find a known point, draw an accurate survey map from your field notes, use topographic surveys, and the right way to level and set grade. You'll learn how to make a survey for any residential or commercial lot, driveway, road, or bridge – including how to figure cuts and fills and calculate excavation quantities. Use this guide to make your own surveys, or just read and verify the accuracy of surveys made by others. 1 Introduction to Land Surveying, 9 The History of the U.S. Land Surveys, 10 4 Using a Transit and Tape, 43 5 Applied Geometry Using a Transit, 65 Using an Established Point, 66 Finding a Perpendicular Line, 66 Establishing Parallel Lines, 67 Dividing a Line Into Equal Parts, 68 Drawing a Circle Through Three Points, 73 Geometry You'll Need to Know, 85 Making a Topographic Survey, 97 Finding Missing Measurements, 148 Before Construction Begins, 170 15 True North, Latitude, and Longitude, 177 Locating by Latitude and Longitude, 182 B Geometry for Construction, 193 C Trigonometry for Construction, 225 D More Practical Examples, 231 Your community library probably has several books on surveying. Many have been written. But nearly all are technical and detailed, offering far more theory and much greater depth than builders and contractors need. That's too bad, because most builders and many tradesmen need a working knowledge of basic survey principles. On every job someone has to find or verify the location of lot corners, align foundation, walls and floors, lay out perpendicular and parallel lines, mark angles, set grade or calculate cut and fill quantities. Professional surveyors can do this work, of course. But you don't need to hire a professional to check a boundary line or lay out a driveway. After reading this manual, I think you'll agree that most of the survey and layout work on a construction site is relatively easy. Anyone with the desire and time available can master the skills required. This manual should meet your needs precisely if you want to learn construction surveying and layout, but don't have the patience to wade through a detailed, theoretical surveying text. I'll emphasize the practical rather than the theoretical and focus on the type of survey and layout problems you're likely to face on your next job. If knowing how to make a simple survey will help in your construction work, you're reading the right book. I'll cover all the practical surveying and layout you're likely to need for any construction project. If you're concerned that your math skills may not meet the challenge presented by the more complex survey problems, don't worry. I've simplified the trigonometry, geometry and mathematics throughout this volume. If you come to a symbol or calculation you don't understand, a little study of the appendix should clarify the point. Appendix B summarizes all the geometry you need to know and Appendix C explains the essentials of trigonometry. Before we get into the first chapter, let me emphasize how important good survey practice is in construction. We've all heard sad stories about homes, apartments or garages that have been built on the wrong lot or straddling a property line. Fortunately, that's not a common error. But it's nearly always a very expensive mistake. Much more usual are foundations that aren't level, slab corners that aren't square, circles that are more like ellipses and ellipses that aren't like anything at all. These all begin with survey mistakes. But that's just the beginning. Anything that's not level, square and true in construction tends to affect every part of the job that follows. You begin with a foundation wall that isn't square at a corner and end up with roof sheathing panels that don't fit right. Introduction to Land Surveying Land surveying allows a surveyor to precisely determine the area of any part of the earth's surface, the lengths and bearings (direction) of all the boundary lines, the contours of features of the land, and to accurately describe all of this information on a map. A knowledge of surveying is indispensable if you are a builder, contractor, or developer. Not only will you often need to hire surveyors, check their findings, and read survey data and maps, occasionally you may be both the builder and the surveyor on a project. There's certainly no better way to find out about every aspect of the site you're developing. This book describes the mathematics behind surveying, the instruments used to take measurements, the method for surveying a site, and the procedure for drawing accurate maps. You'll learn how to take complex measurements for roads, buildings, and bridges; how to establish grades for areas of cut and fill; and how to solve problems that may occur during a survey. The first thing you'll find out is how surveys actually started in the United States. The History of U.S. Land Surveys Land surveys made by government authority follow a definite system provided by law. These are United States Land Surveys. They began on May 18, 1775, when the Continental Congress called for a method of measuring and disposing of some lands claimed by the state of Virginia, which at that time included areas of West Virginia, Kentucky, and Ohio. Accordingly, the Manual of Instructions for the Survey of the Public Lands of the United States was developed. It describes the conditions of the rectangular system of surveys that is required for U.S. land surveys. Longitude and Latitude The rectangular system uses the longitude and latitude lines of the earth as its base. The longitude lines, called meridians, run north and south from pole to pole and at 90º to the equator. Latitude lines, called parallels of latitude, run east and west around the earth parallel to the equator. The equator is 0º. Parallels of latitude are 90º north of the equator (north latitude) and 90º south of the equator (south latitude). Longitude and latitude are stated in degrees, minutes, and seconds. Initial Points Under this system the initial point of a survey is referenced by longitude and latitude by astronomical methods, and marked accurately, called monumenting. This is done so that it's easy to identify exactly where the survey was started and, thus, exactly which piece of land is being described. Initial points were established throughout the public domain by monumented meridian lines and baselines. Each meridian is identified by a name and number. These are listed in the manual of instructions. Land Divisions The rectangular system was first used to survey Ohio. It began at the point where the Ohio River leaves Pennsylvania. This rectangular system of surveying with official requirements was created because surveys are used as the basis for the land descriptions used in deeds. A deed is a legal document describing a certain piece of land that you own. So, if everyone used a different method of surveying for describing that land, no one would be sure who owned what. Deeds describe the initial point of the survey and use bearings to describe the boundaries of the land in question. Figure 1-4 shows how a survey plane is divided into four quadrants, each 90º. The bearing is then referenced for every case, from the north-south line. For instance, bearing N30ºE runs north by east 30º from the north-south line and bearing S30ºW runs south by west 30º from the north-south line. Since this parcel of land is in the northwest quarter (NW 1/4) of the southwest quarter (SW 1/4), the introductory paragraph of your land deed will read: Thence 500 feet due south along the east line of said 1/4-1/4 to a point in said line; thence 356 feet due west to an existing fence comer, said comer being the place of beginning for this survey. thence N84º23'W along a fence line a distance of 165 feet to a point in said fence line; thence S5º19'25.51";W a distance of 276.66 feet to a point in an open field; thence S84º23'E a distance of 165 feet to a point in an open field; thence N5º19'25.51";E a distance of 276.66 feet to a point, said point being the fence comer at the place of beginning for this survey, said survey containing 1.05 acres, more or less. Notice that in descriptions of a survey bearing, the words north, south, east, and west, are not used alone. For instance, the bearing on the east line of the 1/4-1/4 (Figure 1-5), is described as being "due north." This is the back bearing for the bearing given as "due south" in the deed description. Always use the word "due" with the cardinal direction. Now you know how surveys began and how they are used to write deeds. The next step is to find out how to do a survey using the instruments and methods described in the following chapters. (please look at our rules and privacy policy) |
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