Permanent-way practice: For inspection and packing of ballast around cast-iron pot sleepers, how many packing holes are provided in each pot sleeper?

Introduction / Context:
In traditional Indian permanent-way practice, cast-iron pot sleepers were widely used. For maintenance (tamping/packing of ballast) and quick inspection, specific openings are cast into the sleeper. Knowing the number and purpose of these holes is a basic track-maintenance competency.

Given Data / Assumptions:

• Sleepers are pot-type cast-iron units.
• Maintenance requires periodic packing/tamping of ballast beneath rail seats.
• Openings in the sleeper are dedicated to packing and visual checking.

Concept / Approach:
Pot sleepers are designed with packing holes to let tools reach the ballast and to allow easy inspection of its condition. Too few holes would hinder maintenance; too many would weaken the casting and add cost. Standard CI pot sleepers therefore adopt two holes balanced around the rail seat region to facilitate packing.

Step-by-Step Solution:
Confirm the sleeper type: cast-iron pot sleeper.Relate maintenance need: packing tools must access ballast effectively.Design choice: provide two packing/inspection holes per sleeper for adequate access without compromising strength.

Verification / Alternative check:
Practice manuals and legacy drawings show two circular openings in a typical CI pot sleeper precisely for ballast packing and inspection access.

Why Other Options Are Wrong:

• One hole: inadequate access for uniform packing.
• Three or four holes: unnecessary and may weaken the casting or complicate manufacture.
• None of these: contradicts standard practice.

Common Pitfalls:

• Confusing pot sleepers with plate or box sleepers, which have different shapes and features.

Final Answer:
Two holes.