What Are Chaining Errors?
Chaining errors are errors that occur when multiple steps are taken to calculate a result. These errors can accumulate and be either negative or positive depending on the result.
Types of Chaining Errors
There are two types of chaining errors that can occur: cumulative error and compensating error. A cumulative error is one that increases with each step of the calculation, resulting in an incorrect result. A compensating error is one that decreases with each step, resulting in a correct result.
Impact of Chaining Errors
The impact of chaining errors can vary depending on the size of the error and the number of steps taken in the calculation. Small errors tend to have less of an impact than larger errors, while longer calculations can increase the overall impact of the errors.
Cumulative Error and Compensating Error
Cumulative Error
Cumulative error is an error that occurs during the chaining process in the same direction. This type of error accumulates as the chaining process progresses.
Compensating Error
Compensating error is an error that occurs in either directions during the chaining process. These errors compensate for each other, meaning that the values balance out.
Causes of Errors
1.Erroneous Length of Chain or Tape:
Errors in the chaining process in surveying can be caused by an incorrect length of chain or tape used in the process. This can be due to faulty or inaccurate measurement of the chain or tape, leading to an incorrect length being used. This can lead to incorrect results in the surveying process.
2.Inefficient Ranging:
Another potential cause of errors in the chaining process in surveying is inefficient ranging. This is when the surveyor fails to accurately measure and record the distances between the points being surveyed. This can lead to incorrect results, as the recorded measurements may not be accurate.
3.Inefficient Straightening:
Errors can also be caused by inefficient straightening of the chain or tape. This is when the surveyor fails to ensure the chain or tape is straight and level when measuring the distances between the points being surveyed. If the chain or tape is not straight and level, this can lead to incorrect results.
4.Careless Holding and Marking:
Errors in the chaining process can also be caused by careless holding and marking of the chain or tape. This is when the surveyor fails to accurately measure and mark the distances between the points being surveyed. This can lead to incorrect results, as the recorded measurements may not be accurate.
5.Sag in Chain:
Errors in the chaining process can also be caused by the chain or tape sagging. This is when the chain or tape is not held taut when measuring the distances between the points being surveyed. This can lead to inaccurate results, as the recorded measurements may not be accurate.
6.Personal Mistakes:
Errors in the chaining process can also be caused by personal mistakes. This is when the surveyor fails to accurately measure and record the distances between the points being surveyed. This can lead to incorrect results, as the recorded measurements may not be accurate.
7.Variations in Pull:
Errors in the chaining process can also be caused by variations in the pull of the chain or tape. This is when the surveyor does not pull the chain or tape taut when measuring the distances between the points being surveyed. This can lead to incorrect results, as the recorded measurements may not be accurate.
8.Variations in Temperature:
Errors in the chaining process can also be caused by variations in temperature. This is when the temperature of the chain or tape changes when measuring the distances between the points being surveyed. This can lead to incorrect results, as the recorded measurements may not be accurate.
9.Non-Horizontality:
Errors in the chaining process can also be caused by non-horizontality of the chain or tape. This is when the chain or tape is not held horizontally when measuring the distances between the points being surveyed. This can lead to incorrect results, as the recorded measurements may not be accurate.
1. Erroneous Length of the Chain or the Tape
What is a cumulative error?
A cumulative error is an error that can take either a positive or a negative value. It is caused by the wrong length of the chain which is one of the serious errors.
How is the cumulative error affected by the length of the chain?
When the length of the chain is long, the measured distance is smaller resulting in a negative error. On the other hand, when the length of the chain is short, the measured distance is longer and the error is positive.
How to prevent the cumulative error?
Regular and timely checking of the chain can help to provide corrections and prevent the cumulative error.
2. Errors due to Inefficient Ranging
What is Inefficient Ranging?
Inefficient ranging is a surveying mistake which involves placing the chain out of the survey line. This mistake always results in a longer distance value and is a positive error which is also a cumulative error type.
What is the Impact of Inefficient Ranging?
For each repetition of this mistake, the error is cumulative and the final effect on the result is large. If offset distance is also measured, then the error becomes even more serious.
3. Errors due to Inefficient Straightening
Measuring Sloped or Irregular Ground
When measuring a sloped or irregular ground, it is important to ensure that the chain is held straight. This is because any deviation from a straight line will lead to a cumulative positive error, resulting in a measurement that is greater than the true length.
4. Errors due to Careless Holding and Markings
Error Caused by Inexperienced Chain Men
A common error often seen when using a chain is caused by an inexperienced chain man. If the follower does not hold the handle correctly, either one side of the arrow or the other end, the leader may proceed with the work and mark the points without noticing. This type of error is known as a compensating error, as it can generally be corrected.
Compensating Errors
Compensating errors are caused by inexperienced chain men who do not hold the handle of the chain correctly. If the follower holds the handle to either side of the arrow or the other end, the leader may not notice and proceed with the work and mark the points. These errors can generally be corrected, although it is important to ensure that the chain man is experienced enough to avoid this kind of mistake.
5. Error due to Sag in Chain
What is a Cumulative Positive Error?
A cumulative positive error is an error in measuring sloped or stepped ground where the chain has the tendency to sag, resulting in a higher value than the actual measurement.
How does a Cumulative Positive Error Occur?
Cumulative positive errors occur when measuring sloped or stepped ground, as the chain has the tendency to sag, resulting in higher values than the actual measurement. This is because the chain’s sag results in an overestimation of the ground’s height.
What are the Consequences of a Cumulative Positive Error?
The consequence of a cumulative positive error is an overestimation of the ground’s height, which can lead to inaccurate measurements and incorrect results. This can have a significant impact on the accuracy of the results and can lead to costly mistakes.
6. Personal Mistakes
Common Errors in Chaining
Displacement of Arrows:
Displacement of arrows is one of the most common errors encountered in chaining. This occurs when the arrow is moved from its original location, thus affecting the accuracy of the measurements. To avoid this, it is important to mark a point on the ground while fixing the arrow.
Misreading:
Misreading is another common mistake made while taking measurements with a chain. This usually occurs when there is confusion between the 5m and 15m tally of the chain, or between 6 and 9. To avoid this, it is important to be careful while reading the measurements.
Miscounting the Chain Length:
Miscounting the chain length is another common error when chaining. This can be avoided by following a systematic procedure to count the number of arrows.
Erroneous Booking:
Erroneous booking is another error that can occur when taking measurements with a chain. This can be avoided by having the chainman say the reading loud and the surveyor repeating it out loud and entering it in the field book.
7. Errors due to Variation in Pull
Calibrated Pull of a Chain
A calibrated pull of a chain is the exact amount of pull that should be applied to the chain to ensure accurate measurement results. When a chainman applies more or less pull than is calibrated, the error in measurement results is cumulative.
Compensating Error
When the pull applied to a chain is not known, the resulting error is known as compensating error. This error can be caused by the chainman applying too much, or too little pull to the chain. This can result in inaccurate measurement results.
Impact of Applying Too Much or Too Little Pull
If the chainman applies too much or too little pull to the chain, it can lead to cumulative errors in the measurement results. This can cause inaccurate results and lead to costly mistakes in the construction process.
8. Errors due to Variation in Temperature
What is Cumulative Error?
Cumulative error is an error that accumulates over time, resulting in either a positive or negative value. It is most commonly seen in measuring systems that rely on the use of tapes, such as length measuring systems.
How Does Cumulative Error Occur?
Cumulative error can occur when tapes are used to measure lengths. This is because tapes are calibrated to achieve a certain length at a certain temperature. If the temperature of the tape is not the same as the calibrated temperature, then the length of the tape can vary, resulting in errors in the final measurement. These errors can be either positive or negative, depending on whether the tape has become longer or shorter due to the temperature change.
What Are the Implications of Cumulative Error?
The implications of cumulative error are that measurements taken with tapes may not be accurate. This is because the temperature of the tape can affect its length, resulting in errors in the measurement. Furthermore, these errors can be either positive or negative, meaning that the measurement can either be greater than or less than the actual value. This can lead to incorrect conclusions or decisions being made, which can have far-reaching consequences.
9. Errors due to Non-Horizontality
What is a Cumulative Positive Error?
A cumulative positive error occurs when measuring the slope or irregular ground, if the chain is not held horizontally. This results in a longer distance than the actual measurement, resulting in a positive error.