Gary LoRusso Alaska

 

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Gary LoRusso on How Traditional Surveyors’ Tools Work

By keeping up with the latest technological developments in his field, land surveyor Gary LoRusso has an especially clear insight into just how far the industry has advanced throughout the years. With the introduction of amazing new tools such as aerial satellite imagery, global positioning systems, and near limitless electronic data storage, surveyors have more incredibly useful tools than ever before at their disposal.

However, says Gary LoRusso, despite the undeniable usefulness of all of these new technological advancements, many surveyors still make occasional use of many of the same time-tested tools of the trade that they have been using for centuries.

In particular, these tools can be especially useful in work such as the mapping or reestablishment of land boundaries through forests, which often present special challenges for surveyors using GPS devices. As LoRusso explains, survey work through forested areas often needs to be repeated more regularly than other areas, as boundaries and other lines can become lost or moved more easily as forests slowly grow and change over time. Particularly dense forests, however, sometimes interfere with the satellite signal from GPS satellites, making the use of traditional tools necessary.

The most commonly utilized of these traditional tools, both in the past and in certain instances today, are the compass and the chain. Below, he explains how each of these survey tools works.

Measuring Bearings and Angles Accurately with a Traditional Compass

Compasses have always been a vital standby in surveying work, says LoRusso, and traditionally usually came either hand-held or conveniently mounted on a tripod or staff. By using a compass, surveyors could get their initial bearings and set a starting point for their work, both of which are important to collecting accurate data measurements.

Before beginning work, surveyors first needed to set the correct magnetic declination on their compass to account for any known sources of local magnetic interference. This was especially important when surveying land in either the far western or northeastern regions of North America because of more extreme magnetic declination. “Traditional compasses point toward magnetic north, not true north toward the North Pole,” explains land surveyor Gary LoRusso. “Magnetic north can vary as much as 20 degrees in either direction across the continent, so adjusting these compasses accordingly was important to obtaining accurate results and usage.”

When mapping or reestablishing the lines of a property with these compasses, says LoRusso, it was important that surveyors recorded all angles according to their true bearing rather than the value corrected for declination. For less sophisticated compasses without declination settings, this translation of bearings could be performed later at the end of the survey work, although doing so presented more complications and time demands.

 

Gary LoRusso Explains the Uses of the Surveyors’ Chain

“The surveyors’ chain, also called Gunter’s chain, is a traditional unit of horizontal measurement in land surveying,” LoRusso explains. “It has long been used by surveyors, foresters, and forest owners as the preferred unit of measurement for all public United States Government Land Survey work, especially the land west of the Mississippi River.”

This uniformity of measurement ensured that survey data was easier to interpret and compare. The widespread use of this measurement was adopted after being used in the original survey work of most public land and forest boundaries throughout the country.

 

Calculating Acreage from Chain Measurements

“One important reason for the traditional use of the chain, as well as its adoption to a uniform standard, is its ease of conversion,” LoRusso explains. “Converting chained dimensions into acreage was simple and could be accomplished through a fairly basic calculation. This is why the tool was adopted traditionally and why we still refer to the measurement unit today.”

Converting square chains into acres required only the division of the former measurement by ten, as one acre is exactly equal to ten square chains. “To make calculations even easier,” says LoRusso, “what we call a ‘section’ of land is an area measured 80 chains on each side. This makes 640 acres of land, or a single square mile. These sections could then be easily quartered into 160 acre lots, or again into 40 acre lots.”

 

Using a Traditional Chain to Measure Horizontal Distance

 

“Before technological advancements in the field, foresters and land surveyors typically used one of two methods to measure any horizontal distance of the area they were working on,” says LoRusso. “These methods were pacing and chaining.”

Of the two, he says, chaining created more accurate and exact measurements. “To chain a distance, you needed two people, a compass, and a surveyors’ chain, which is a steel tape measuring 66 feet long,” says LoRusso. “The rear surveyor used the compass to find the correct bearing, and the front surveyor dropped the length of the chain along that bearing. These drop points were measured with pins to indicate the number of chains contained within a distance.”

Pacing, however, also had its uses, says LoRusso. “Pacing was a rudimentary way to roughly but quickly estimate a distance,” he explains. “If you didn’t have the time, the help, or the equipment to drop a chain for more accurate readings, pacing would often suffice temporarily.”

ABOUT:

As a land surveyor and property developer, LoRusso provides many important services for his community of Palmer, AK. Most of his work is done through Keystone Surveying & Mapping, a surveying and developing company that he founded himself in 1991. Through his dedication to keeping current with the latest technological advancements and trends in his field, Gary LoRusso has made himself a highly active expert in the surveying industry.