Preferred rail section for heavy Broad Gauge main lines On B.G. main lines carrying maximum traffic loads, which rail section (weight per metre) is generally preferred?

Introduction / Context:
Heavier rail sections better resist bending, wear, and contact stresses on busy main lines. Indian Broad Gauge (B.G.) routes with high axle loads and traffic intensity typically employ heavier rail weights.

Given Data / Assumptions:

• Units are weight per metre (kg/m) for standard rail designation.
• The question asks for the range suited to heavy B.G. main lines.

Concept / Approach:
B.G. main lines under maximum traffic loads commonly adopt rail sections in the range of approximately 45 to 57 kg/m. This ensures adequate section modulus and durability, reducing frequency of renewals and maintenance.

Step-by-Step Solution:
Identify the options with correct units (kg/m vs kg/cm).Recognize that 44.7–56.8 kg/m aligns with heavy main-line practice.Select 44.7 to 56.8 kg/m as the preferred range.

Verification / Alternative check:
Track standards and procurement records consistently list heavier rails for busy routes, matching the 52 kg and 60 kg class commonly referenced (approximate to the given range).

Why Other Options Are Wrong:

• 29.8–37.3 kg/m: lighter sections suited to lighter traffic or branch lines.
• Options in kg/cm: unit error; rails are specified in kg/m.
• None: incorrect because a suitable range is provided.

Common Pitfalls:
Missing unit consistency; confusing nominal catalogue weights with exact in-service designations.

Final Answer:
44.7 to 56.8 kg/m