Rail section designation: A rail section is generally designated by which parameter?
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ATotal weight of the rail batch
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BTotal length of a standard rail
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CWeight per metre length of the rail
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DArea of cross-section only
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EMoment of inertia of the section
Answer
Correct Answer: Weight per metre length of the rail
Explanation
Introduction / Context:Rail sections are standardized and identified for procurement, design, and maintenance. A clear designation convention ensures uniformity across drawings, specifications, and logistics documentation.
Given Data / Assumptions:
- Rails of different profiles (e.g., 60 kg/m, 52 kg/m) used for various load and speed categories.
- Section properties scale with mass per unit length.
Concept / Approach:Rails are generally designated by their mass per metre (e.g., 60 kg/m). This single metric is practical and correlates with section modulus, stiffness, and load capability. While area and inertia are important for analysis, the mass-per-metre designation is universally recognized for identification.
Step-by-Step Solution:1) Recognize designation must be simple and uniformly applicable.2) Weight per metre succinctly captures section size and capacity.3) Hence rails are commonly referred to as ’’X kg/m’’ sections.
Verification / Alternative check:Standards and catalogues list rail types by mass per metre, with associated drawings providing exact dimensions and properties.
Why Other Options Are Wrong:
- Total batch weight or total length does not identify section.
- Area or inertia alone is not the standard naming convention in practice.
Common Pitfalls:
- Confusing designation (kg/m) with total piece length (e.g., 13 m rails).
Final Answer:Weight per metre length of the rail.