Historians aren’t quite sure who made the prehistoric monument at Stonehenge, but they know that early surveying equipment was used. In fact, most ancient civilizations relied on simple geometry and surveying tools to establish land borders and boundaries for building, farming, and city planning. The Romans, for example, built the most advanced system of roads the world had ever seen with the help of land surveyors. Here’s a brief look back at how the profession has changed since those early days.
Equipment: Development and Improvement
Before the 18th century, most surveyors used ropes and chains to measure distance. The great leap forward occurred in 1787, when the first precision theodolite was introduced. The instrument simultaneously measures angles on both vertical and horizontal planes. It helped surveyors quickly and accurately measure angles to distant points, which was invaluable for map making.
But as important as the theodolite was, surveyors still had to manually measure distances to ensure precision. It was not until electronic distance measurement (EDM) was developed in the 1950s that they could finally put away their ropes and chains. The device utilizes microwave transmitters and receivers to determine long distances. Building on this advancement, instruments that measured both distance and angles came on the scene in the 1970s. Known as total stations, their speed and accuracy have continued to improve at an impressive pace. Modern stations can even be operated by remote control!
At present, the theodolite and the total station are considered essential pieces of equipment for professional surveyors. Although GPS technology has come a long way in recent years, it does not yet provide the accuracy and precision professionals need to do their job. As such, GPS equipment is rarely used to the exclusion of more trusted surveying tools.
Measurement Conversions
Because most surveying tools use the metric system, U.S. surveyors must convert their measurements from meters to feet (1 meter = 3.28 feet). Even more confusing is a unit of length and area known as a rod. Used primarily in older property deeds, one rod is equal to 16.5 feet. For federal surveyors who complete U.S. public land surveys, an ancient measurement unit called a chain is still in use. Originally consisting of 100 iron links that were nearly eight inches long, a standard chain is 66 feet in length.
Although the tools and technologies have changed, many ancient units of measurement are still in place today. For the average residential surveyor, it is often enough to simply convert metric measurements to imperial (U.S.) ones. But for federal surveyors, a more complex system based on ancient measurements is still in use.
