Errors in Chaining | Guide to Surveying and Levelling

Types of Errors occurring in Chain Surveying

There are two types of Errors that are commonly seen to occur in Chain Surveying. For students studying the concept of Chain Surveying, study of the occurrence of different types of Errors in Chain Surveying is important. In this article, we will briefly discuss different types of Errors in Chain Surveying and the situations in which they occur.

Types of Errors:

1. Cumulative error
2. Compensative error

Cumulative error

These errors always accumulate in one direction and are serious in nature. They affect the survey work considerably.

They make measurements too long or too short.

These errors are of two types and are known as systematic errors.

They are classified as follows:

1. Positive error
2. Negative error

Positive error

These errors make the measured length more than the actual length which results into wrong calculations by the Surveyor.

The following are some of the positive errors:

• The length of chain is shorter than the standard length due to bending of links, removal of connecting rings and knots in links.
• The temperature is lower than at which the tape was calibrated.
• Not applying sag correction.
• Sag takes place due to self weight of the chain.
• Incorrect alignment

Negative errors

These errors make the measured length less than the actual length.

Following are some of the negative errors:

Length of chain or tape greater than its standard length due to flattening of rings, opening of ring joints and temperature being higher than at which it was standardised.

Compensative errors

These errors occur in either direction and are likely to compensate.

These occur in following situations:

• Incorrect holding of chain
• Displacement of arrows
• Adding or omitting a full length of chain
• Reading wrongly
• Booking wrongly