In earthwork/payment classification, which excavation items are measured in square metres (sq.m) rather than cubic metres (cu.m)?

Introduction / Context:
Correct units are crucial for estimating and paying for earthwork. Shallow, spread-out operations are commonly measured by surface area, while bulk diggings are measured by volume. Recognising which items fall into each category prevents contractual disputes.

Given Data / Assumptions:

• “Surface dressing” is a shallow operation, typically limited to about 15 cm depth.
• “Surface excavation” is slightly deeper but still shallow (up to about 30 cm).
• “Ordinary cutting” refers to deeper excavation, e.g., up to 1 m depth or more.

Concept / Approach:
Area measurement (sq.m) is appropriate when depth is standardized and small, so cost primarily scales with the plan area treated. Deeper excavation with significant variable depths is measured by volume (cu.m) because removed material depends on both area and depth.

Step-by-Step Solution:
Surface dressing up to 15 cm: paid in sq.m — yes.Surface excavation up to 30 cm: also measured in sq.m — yes.Ordinary cutting up to 1 m: measured in cu.m — not sq.m.Therefore, items (b) and (c) are the ones measured in sq.m.

Verification / Alternative check:
Schedules of Rates and standard measurement books list separate items for surface dressing/excavation by area and bulk excavation by volume.

Why Other Options Are Wrong:

• (a) involves substantial depth; it is measured volumetrically.
• (e) incorrectly includes (a).

Common Pitfalls:
Confusing superficial works with bulk earthwork; forgetting depth limits that switch the unit from area to volume.

Final Answer:
Both (b) and (c)