Metric chains used in chain surveying Which standard lengths are metric chains generally available in for field measurements?

Introduction / Context:
Metric chains replaced Gunter’s chain for metricated surveying systems. Knowing the standard chain lengths helps in planning offsets, stations, and the selection of accessories such as arrows and ranging rods.

Given Data / Assumptions:

• We are dealing with standard, commonly manufactured metric chains.
• Lengths are set so that links and tallies provide convenient subdivision.

Concept / Approach:

Metric chains are typically standardized at 20 m and 30 m. These lengths align with common tape measures and allow easy conversion to hectares and square meters when computing areas from chained distances.

Step-by-Step Solution:

Verification / Alternative check:

Survey equipment catalogs and textbooks list metric chains predominantly in 20 m and 30 m, with appropriate tagging at 5 m or 3 m intervals depending on design.

Why Other Options Are Wrong:

Options A, B, D, and E list combinations that are not the conventional metric chain standards though some lengths might be found for tapes or special cases.

Common Pitfalls:

Confusing tape lengths (which can be many sizes) with standardized metric chain lengths.

Final Answer:

20 m and 30 m