In the heading-and-benching method of tunnelling, identify the statement that is NOT correct about work sequencing, access, and muck removal efficiency.

Introduction / Context:The heading-and-benching method divides the tunnel face into an upper ‘‘heading’’ portion and a lower ‘‘bench.’’ This staged approach aims to improve access and allow overlapping operations. However, not every aspect becomes easier—especially muck removal from the higher heading area, which remains constrained by space and logistics. Understanding these nuances is essential for planning productivity and safety.

Given Data / Assumptions:

• The method involves two levels: heading (top) and bench (bottom).
• Operations include drilling, blasting, mucking, and support installation.
• We must spot the statement that is not correct.

Concept / Approach:

While the bench offers a working platform and can facilitate simultaneous activities (e.g., mucking at bench while drilling in heading), removal of muck specifically from the heading is not ‘‘very easy’’ due to elevation differences, chuting, and equipment maneuverability limits. Hence, that statement is the incorrect one.

Step-by-Step Solution:

Verification / Alternative check:

Construction reports frequently note bottlenecks at the heading for cleanup, scaling, and support, confirming that the heading portion is the more difficult zone for muck handling compared with the bench level.

Why Other Options Are Wrong:

• Simultaneous drilling and mucking: One of the method’s advantages.
• Benching provides a platform: True by definition of the method.
• None of these: Incorrect because one statement is indeed not correct.
• Benching improves safety by separating zones: Generally true in practice.

Common Pitfalls:

• Overstating productivity gains while underestimating heading congestion.
• Ignoring ventilation and scaling needs that further complicate heading muck removal.

Final Answer:

Removal of muck from the heading is very easy