List four errors found in chain survey and calculate the reduced levels of the survey in figure 6.

c) List four errors found in chain survey

• Incorrect ranging: The chain is not laid in a straight line between survey stations.
• Incorrect chaining: Errors in measuring the length, such as applying incorrect tension, allowing sag, or not straightening kinks in the chain.
• Displacement of arrows: The marking arrows used to denote chain lengths are moved or lost.
• Careless plumbing: The plumb bob is not held accurately over the station point, especially on sloping ground.

d) Calculate the reduced levels of the survey carried out as seen in the diagram in figure 6.

Step 1: Extract the readings from Figure 6.

• BS on BM: $0.8