If you’re working in surveying, it’s important to be aware of the potential for both systematic and random errors in your measurements.
An error means the difference between what we measure and what is actually true. Every measurement has some amount of error because it is impossible to measure things perfectly (except when we’re counting). However, we can try to minimize errors by using skilled techniques and accurate equipment. To figure out the true value of a measurement, we need to take many measurements and calculate the average.
Systematic Errors in Surveying
Systematic errors are errors that can be identified by their size and direction. Because we can figure out what these errors are, we can fix them and make our measurements more accurate. One example of a systematic error is when a steel tape used for measuring gets warm. When the temperature rises, the steel tape expands, which makes it longer than it should be.
This can cause a systematic error in our measurements. For instance, when it’s 83°F outside, a 100-ft steel tape can expand to 100.01 ft, which is a systematic error of 0.01 ft. But if we know about this error, we can simply subtract 0.01 ft each time we use the tape at that temperature. This helps us get rid of the systematic error and make our measurements more precise.
Random Errors in Surveying
Random errors, also called accidental errors, happen when a surveyor makes mistakes due to their skill and attention level. These types of errors are unavoidable because no one is perfect.
For example, let’s say a surveyor needs to find point B, which is 109.55 feet away from point A. If their measuring tape is only 100 feet long, they will need to set an intermediate point at 100 feet and then measure the remaining 9.55 feet from there. During the process of marking out the 100 feet, the surveyor may make a small mistake and mark it as 99.99 or 99.98 feet.
When measuring the remaining 9.55 feet, there are two more opportunities for errors. The lead surveyor may make the same mistake as before, and the rear surveyor may accidentally hold the tape at a slightly different measurement, like 0.01 feet instead of 0 feet.
One important thing to note about random errors is that their magnitude is unknown. It’s impossible to predict exactly how much the surveyor will be off by. However, because the surveyor is likely to make both overestimations and underestimations, random errors tend to cancel each other out over time.
However, it’s essential to be careful when performing surveys, as large random errors can give the appearance of accuracy, even when the results are highly inaccurate. Sloppy work can be just as dangerous as intentional mistakes.
Also Read: 5 Types of Chains and Tapes in Civil Surveying Engineering
Frequently Asked Questions
What is an error in measurement?
An error in measurement refers to the difference between the measured value and the actual value of a quantity. It is impossible to measure things perfectly, so every measurement has some amount of error.
What are systematic errors in surveying?
Systematic errors in surveying are errors that can be identified by their size and direction. These errors can be fixed, and measurements can be made more accurate.
What are random errors in surveying?
Random errors in surveying, also called accidental errors, occur due to the surveyor’s skill and attention level. They are unavoidable because no one is perfect.
Can large random errors give the appearance of accuracy in surveying?
Yes, large random errors can give the appearance of accuracy in surveying, even when the results are highly inaccurate. Sloppy work can be just as dangerous as intentional mistakes.
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