What is the minimum number of headings that must be ventilated with intake air in a group of main roads that are being driven this year?

• A. 0
• B. 2
• C. 3
• D. 4

Answer: (B)

Fresh air must be brought into an underground group of main road headings through intake air feeds. Having more than one intake path helps distribute the air evenly across the entire group and provides redundancy if one heading becomes blocked or contaminated. This reduces the risk of methane or dust buildup and ensures every heading gets adequate fresh air. Two intake air headings is the smallest setup that still achieves reliable, adequate distribution for the group. Zero intake headings would mean no fresh air supply, which is unsafe, and three or four would exceed the minimum requirement for this scenario. Hence, two is the correct minimum.