The Surveying Handbook

This chapter provides information about the professional organizations and their role in professional surveying. Addresses of key organizations are included in that direct contact can be made to obtain further information.

Surveying is defined in the 1978

ASCE Manual No. 34: Definitions of Surveying and Associated Ternis

prepared by a joint committee of the ASCE and ACSM as

“(1) The science and art of making all essential measurements in space to determine the relative positions and points and/or physical and cultural details above, on, or beneath the earth’s surface and to depict them in usable form, or to establish the position of points and/or details. Also, the actual making of a survey and recording and/or delineation of dimensions and details for subsequent use. (2) The acquiring and/or accumulation or qualitative information and quantitative data by observing, counting, classifying, and recording according to need.”

Examples are traffic surveying and soil surveying

Surveying is the art and science of making measurements. The notion of “exact” measurement, of “perfect” result, of “accurate” work is quickly dispelled when trying to duplicate an angle or distance measurement or difference of elevation. It is also evident when different people make the same measurement.

Surveyors are fundamentally concerned with the measurement of horizontal and vertical distances and angles and, more recently, with direct positioning. These, then, are used in various combinations in traversing, triangulation, trilateration, mixed-mode operations, mapping, layout staking, leveling, etc.

Electronic measurement is a modern method of precise and rapid determination of slope (line-of-sight) distances. Some electronic distance-measuring instruments (EDMIs) are designed to reduce the slope distances to horizontal distances.

Three dimensions or combinations thereof must be measured to locate an object with reference to a known position: (1) horizontal length, (2) difference in height (elevation), and (3) angular direction. This chapter discusses the design and uses of surveyors’ transits and theodolites to measure horizontal and vertical angles.

Leveling is a process to determine the vertical position of different points below, on, or above the ground. In surveying operations, vertical elevations and vertical control are generally derived independently of horizontal control. Some modern positioning devices, termed total stations, allow simultaneous determination of spatial coordinates. Elevation is the vertical distance above a well known datum or arbitrary reference surface. Elevations are helpful for the placement of a water drain line to provide free gravity flow, construction of a sports playing field, and among other applications, the vertical layout of a roadbed to allow a smooth flow of trucks and trains, which must ascend or descend sloping terrain.

Surveying instruments are very durable, but delicate and precise pieces of equipment. No matter how well an instrument has been adjusted, rough handling, temperature variations, humidity, and a host of other factors can quickly affect its precision. The safest rule a surveyor can follow is to keep an instrument adjusted, but then use it as if it is not adjusted.

A traverse is a series of consecutive straight lines along the path of a survey, the lengths and directions of which are or have been determined by field measurements. The surveying performed to evaluate such field measurements is known as traversing. Although often used in land and route surveying, it is also employed in other types of surveying.

A sketch, map, or graphic display, is often the only visible product of a surveyor’s work. Therefore, the importance of presenting the client with a nice-appearing, professionally done graphic product cannot be overemphasized. Attractiveness, accuracy of plot, legibility, and clearly imparted information are vital in creating a survey drafting product worthy of professional respect.

Triangulation is the surveying technique in which unknown distances between stations may be determined by trigonometric applications of a triangle or triangles. In triangulation, one side called the baseline and at least two interior angles of the triangle must be measured. When all three interior angles are measured, accuracy of the calculated distances is increased and a check provided against any measurement error.

Trilateration is a method of control extension, control breakdown, and control densification that employs electronic distance-measuring instruments (EDMIs) to measure the lengths of triangles sides rather than horizontal angles, as in triangulation. The triangle angles are then calculated based upon measured distances by the familiar law of cosines. Trilateration consists of a system of joined and/or overlapping triangles usually forming quadrilaterals or polygons, with supplemental horizontal angle observations to provide azimuth control or check angles. Zenith angles are required when elevations have not been established or differential leveling is not contemplated, in order to reduce slope distances to a common reference datum.

Literally, the word geodesy means “dividing the earth”; however, by usage its meaning now includes both science and art. The science of geodesy is devoted to determining the earth’s size, shape, and gravity field. The art of geodesy utilizes scientific data in a practical way to (1) obtain latitude, longitude, and elevation of points; (2) compute lengths and directions of lines on the earth’s surface; and (3) describe the trajectory of missiles, satellites, or other spacecraft. It is not intended here to designate a given activity as being either science or art, but to recognize a legitimate difference in emphasis that may exist in various areas of geodesy.

Godetic control networks have classically been divided into two distinct categories: (1) horizontal and (2) vertical. Each network has its own respective set of monumented pointsi.e., horizontal control (or “triangulation”) stations and bench marks in horizontal and vertical networks, respectively. Similarly, classical control surveying methods are divided into two nearly independent categories: (1) horizontal methods that include traversing (Chapter 9), triangulation (Chapter 11), trilateration (Chapter 12), and combinations of the three; and (2) vertical methods that consist of differential and trigonometric leveling (Chapter 6).

This chapter is not intended to be a text on global positioning surveying. The bibliography contains many other sources that will greatly expand one’s knowledge of the topic to any depth or breadth required. The objective of the chapter is to provide information to eliminate problems commonly experienced by first time users of GPS technology. Some related topics are triangulation (Chapter 11), trilateration (Chapter 12), geodesy (Chapter 13), and inertial and satellite surveys (Chapter 14).

The general subject of errors in measurement was discussed in Chapter 3, and the two classes of errors, systematic and random (or accidental), were defined. It was noted that systematic errors follow physical laws, and that if the conditions producing them are measured, corrections to eliminate these can be computed and applied; however, random errors will still exist in all observed values.

Surveying has been defined as the science of determining positions of points on the earth’s surface. The four components of surveying measurements are: (1) vertical (elevations), (2) horizontal (distances), (3) relative direction (angles), and (4) absolute direction (azimuths). Due to recent developments in technology, the accuracy and efficiency of measuring these first three components have increased dramatically. This has resulted in accurate determination of the size and shape of figures. Unfortunately, determination of the orientation of figures, the fourth component, has not kept pace, even though inexpensive technology and equipment exist, such as precise timepieces, portable time signal receivers, ephemerides, programmable calculators, and computers. The purpose of this chapter is to provide sufficient theory, calculations, and field procedures so surveys in both the northern and southern hemispheres can be accurately oriented without significant increases in time and expense, in both the northern and southern hemispheres.

The earth is round; maps are flat. If a particular map is to show only a very small portion of the earth, such as a few city blocks, the roundness of the earth is insignificant. On the other hand, if a map is to show the western hemisphere, the roundness presents a major problem—i.e., some kind of deformation will be necessary. To illustrate, a large section of orange peel can only be flattened if it is stretched and torn.

It has been common practice for surveyors to use rectangular (X- and Y-) coordinates in surveys. Coordinates are useful in the design and layout of subdivisions, layout of construction control, computation and plotting of traverses, surveying of land boundaries, establishment of mapping control, etc. All too often, however, surveyors have used arbitrary coordinate systems, resulting in thousands of different surveys referred to thousands of unrelated origins. These independent systems are useless for any purpose other than the original one—i.e., the data cannot be conveniently plotted on a map made by others or stored in a data bank or land information system. They cannot be used to relate land boundary corners to each other in adjacent areas, to tie together public works geometrically over large areas, or as control survey reference systems for any purpose except the single one for which they were created.

Photogrammetry has influenced survey practice drastically since its introduction as a mapping tool. Aerial photographs specifically for mapping purposes were first taken in 1913, although ground photography had been used to a limited extent in field surveys as early as 1894.1 The first major mapping project in the United States was conducted by the U.S. Geological Survey and the Tennessee Valley Authority in the 1930s. At that time, some 40,000 sq mi (103,500 sq km) of the Tennessee River basin were mapped. At present, aerial photogrammetry is used for virtually all small-scale mapping done in the United States and is seeing increasing use for large-scale mapping as well.

Compasses discussed in this chapter are devices used to determine direction, with a magnetized needle balanced on a pivot. The needle and pivot are housed in a box containing a circular ring divided into degrees and/or half-degrees. When a compass is held steady and the needle swings freely, it points in a northerly-southerly direction, and the degree mark to which it points can be read on the circle.

The planetable alidade is an articulated hybrid surveying and drafting instrument system that enables a topographer to simply and directly communicate with the map sheet that, in a very real sense, is an extension of the topographer’s perception of a landscape. The instrument is capable of performing all the usual survey functions with the exception of field astronomy. It is also unsurpassed as a basic instrument for teaching fundamental concepts of surveying because the geometric principles are readily grasped, and the objective of a survey operation is clearly indicated on the map sheet.

Control surveys provide horizontal and vertical positions of points to which supplementary surveys are adjusted. Control surveys provide the standard of accuracy for subsequent and subordinate surveys to attain. All projects, including route surveys, photogrammetry, and topographic mapping, are made up of a series of vertical and horizontal field surveys. These secondary surveys are dependent on control for position and relative accuracy.

Construction surveying operations comprise approximately 60% of all surveying work being performed and should be considered a definite specialty of the modern surveyor. Three basic objectives of construction surveying are (1) providing layout stakes, located both horizontally and vertically, that construction personnel can utilize in an accurate and efficient manner to position structures or earthwork projects; (2) ongoing replacement of layout stakes as a project progresses toward completion, along with periodic checking of projects to ensure compliance with design dimensions; and (3) providing a map at the completion of a project, showing the final project location and configuration, incorporating any changes or modifications in project design—an “as-built” map.

Highways, railways, canals, tunnels, dams, pipelines, and transmission lines are constructed works having linear shapes classified as routes. A unique system for expressing route geometry has developed that, once learned, can be applied without fail to this broad range of projects by all surveyors, designers, and constructors.

Hydrographic surveying is the wet equivalent of topographic surveying. Its objective is to delineate the shape of a portion of the earth’s surface concealed by water. The surface being mapped cannot be observed directly or occupied, so it is necessary to infer topography from depth measurements. Simply, it is the process of deducing underwater topography from numerous discrete observations of depth at positions throughout the survey area. The quality of its product depends on the accuracy and density of these observations.

Webster’s Dictionary defines boundary as any line or thing making a limit, whereas Corpus furls Secundum states that a boundary is a line or object indicating the limit or furthest extent of a tract of land or territory; a separating or dividing line between counties, states, districts of territory, or tracts of land.l

Property boundary location along waterways is probably the most complex of all boundary locations. Water lines naturally fluctuate and so any boundary dependent on a fluctuating line must change. This often leads to litigation among litoral owners since a changing property line may cause one person to lose and another to gain. As a result, courts rooted in common law have often established precedents for riparian boundary location based on equity rather than more precise and scientific location principles. In recent years, courts have modified some viewpoints and reversed themselves on others. As a result, boundary location along waterways is fraught with uncertainties, not only in location, but also title. Matters are made worse by unclear laws. What does all of this mean to the surveyor? How does the surveyor begin to understand riparian boundary location? Most important, what does the surveyor need to know to perform the duties and discharge the responsibilities associated with surveying a boundary along a waterway or shoreline.

Surveying and mapping practice in the mining industry encompasses most surveying fields; its main difference is that it has a direct effect on the safety of people working in the mines. Accurate surveys and reliable maps are a prerequisite to a successful mining operation. If an accident occurs, such as a roof fall or an onrush of water or oxygen-deficient air, surveying operations must be performed immediately to aid in rescue efforts. Time is important, and confidence in the surveying and mapping system of the mine is essential. If a rescue borehole is needed, a spatial position must be promptly established on the surface or in an adjacent mine; a good surface-underground three-dimensional coordinate system is required.

The public-land survey system covers all of the continental United States except the original 13 colonies, Texas, and Hawaii. It is a system begun by federal law in 1785 and was largely put in place by 1805. Most changes since that time have been refinements to the system, rather than major revisions. The system established the concept of surveying and marking the land prior to the government’s selling the land to its citizens. Though a novel concept in the world of 1785, it was successful in encouraging rapid settlement of the continent by placing most land in private ownership.

Occasionally, surveyors may be requested to provide very precise dimensional control in the assembly and alignment of aircraft jigs, automobile and farm implement manufacturing, and other machine elements. The term optimal tooling refers to surveying techniques that have been introduced into the aircraft and other industries to make accurate dimensional layouts possible. Many people refer to this process as optical alignment.

Land descriptions are prepared for use in various types of deeds or documents transferring interests in land. They should be clear, complete, and concise identifications of particular pieces of land. A properly written description describes land in a way that avoids any confusion between the intended parcel and other parcels. Unfortunately, every professional land surveyor has encountered many land descriptions (also called legal descriptions) that leave much to be desired. In fact, the history of legal descriptions is one of constant turmoil and chaos.

The expert in any of a number of technical fields is frequently, as a witness or an adviser, drawn into the vortex of land litigation. The expert in the land case may be a surveyor, title abstractor, property appraiser, engineer, geologist, hydrologist, oceanographer, biologist, or geographer. But there is one denominator that, in land cases, each of these experts bears in common with the other. It lies in the role each plays in a land dispute, whether it concerns title, political or property boundaries, water rights, or other aspects of natural resource use. In these cases, the expert’s role is much more like the lawyer’s than the part of an expert in virtually any other kind of law case.

After all phases of surveying, mapping, and other related activities are completed, individuals who are engaged in surveying and mapping sciences may find that their work is just commencing. Whether the individuals conducted a boundary survey, a building stakeout, or prepared a topographic or planimetric map, the product may be questioned by the client or a third party who had no pecuniary interest in the original job. As a result, professionals may be embroiled in a legal action, either as a party or witness defending their work for the client or explaining their actions. In either situation, their professional qualifications and capabilities will be questioned and “hung out to air” for all to see and evaluate.

Over the past decade, the interest in land and geographic information systems (LIS/GIS) has been overwhelming. Surveyors, geographers, engineers, landscape architects, environmentalists, planners, and professionals from a number of other related disciplines have embraced this technology and begun to build information systems to assist them in their work. In the United States, the development of integrated information systems has focused to a large extent on the local level where most land-related information is acquired and maintained. This has been particularly true for highly urbanized areas (cities) where most of the information is related to the property parcel.