Surveying, in general, is the art of measuring and locating lines, angles and elevations on the surface of the earth, within under-ground workings, and on bodies of water. A cadastral survey creates (or reestablishes), marks and defines the boundaries for tracts of land (Bureau of Land Management, 1973). Global Positioning System (GPS) technology has revolutionized the way people survey. Originally developed as a navigation and timing system for military applications, GPS has emerged as a leading technology in surveying. Surveying possibilities with GPS are unlimited. If you can get to it on foot, in a car, a boat or aircraft, you can survey it using GPS.
What is GPS? It? a space-based radio navigation system that is operated for the Federal Government by the Department of Defense (DOD) and jointly managed by DOD and the Department of Transportation (DOT). GPS was originally developed as a military force enhancement system and will continue to function in this role. However, GPS also provides significant benefits to the civilian community. In an effort to make GPS service available to the greatest number of users while ensuring that the national security interests of the United States are protected, two GPS services were originally provided: Precise Positioning Service (PPS) and Standard Positioning Service (SPS).
The Precise Positioning Service (PPS) provided full system accuracy primarily to the United States and allied military users. The Standard Positioning Service (SPS) provided civilian and all other users throughout the world with a less accurate positioning capability than the PPS. SPS was removed from GPS in May 2000.
GPS surveying can be conducted in any weather, at night, without a line of sight requirement, and needs only one person to operate the equipment. A continuous line of data can be recorded tracing a route while driving a road or hiking a trail (Bureau of Land Management. 1991). One of the greatest advantages of GPS is that the data can be collected and transferred electronically. GPS also uses a common reference system; latitude, longitude, and elevation.
The U.S. Government has directed surveying of public lands since 1785, when a beginning point that was established at the west boundary of Pennsylvania as it crosses the north bank of the Ohio River. The first surveys, covered parts of Ohio and were made under the supervision of the Geographer of the United States in compliance with the Ordinance of May 20, 1785. The land was divided into townships plats which are subdivided into sections or lots of one square mile. Each township consists of 36 lots (or square miles) numbered from 1 to 36. (Bureau of Land Management, 1973) The original GLO surveys were made using a standard 100 link survey chain (66 feet long) and a needle compass Each measurement, of their survey, was recorded in chains and links (i.e., 251 links).
Today, with survey grade GPS, measurements can be made to the nearest centimeters. Are today’s advancements in technology improvements that we really need? Were the skills and accuracies of yesterday good enough for land measurements? Is GPS surveying just another way of challenging yesterdays’ skills?
Resurveying and remonumenting a section or a township with GPS is more than just finding old monuments and surveying them in. The township plat furnishes the data relating to the original survey and the description of all areas in the particular township. All title records within the area of the former public domain are based upon a Government grant or patent, with descriptions referring to an official plat. The lands are identified on the ground through the retracement, restoration, and maintenance of the official lines and corners. A knowledge of the practices and survey instructions in effect at the time of the original survey is essential. These instructions will indicate what was required and how the original survey was made.
Today, with GPS, measurements are made to the nearest centimeters. Are today’s advancements in technology improvements that we really need? Were the skills and accuracies of yesterday good enough for land measurements? Just because we can measure land to within a centimeter, is it really required for every survey today? Is GPS surveying simply just another way of challenging yesterdays’ skills or is it just sometimes faster and cheaper?
The real sad side to GPS is it has created the One Person Crew and that has given us the one cry we hear over and over that is “where are the younger Surveyors?” Whenever I hear that I ask, who do you learn your Survey skills from?