Extra ballast on curves and welded rail practice Which of the following statements regarding extra ballast width on curves and welded-rail tracks is correct in permanent-way maintenance practice?

Introduction / Context:
Curved track experiences higher lateral forces due to curvature and cant deficiency. Welded rails (short or long welded) also demand greater lateral resistance from ballast shoulders to prevent buckling and maintain alignment. Hence, standards prescribe extra ballast widths under specific conditions.

Given Data / Assumptions:

• Curves sharper than specified degrees require extra outer shoulder ballast.
• Welded rail track (SWR/LWR/CWR) typically needs extra shoulder on both sides.
• Values such as 7.5 cm or 15 cm are standard augmentation amounts used in practice.

Concept / Approach:
Additional ballast on the outer shoulder of curves counters lateral drift. For welded rails, providing extra ballast on both shoulders increases track lateral and longitudinal resistance, helping to manage thermal forces. Therefore, each listed prescription serves a valid and documented objective in track stability.

Step-by-Step Solution:
Check each statement against typical permanent-way guidelines.7.5 cm extra on outer side for SWR and for curves sharper than about 3° is a recognized practice.15 cm extra on each shoulder for welded rails enhances resistance and is commonly specified.Since all are correct, the combined option is right.

Verification / Alternative check:
Standard ballast profiles and welding manuals provide tabulated extra shoulder requirements for curves and welded sections, confirming these statements in maintenance literature.

Why Other Options Are Wrong:
Individual options are correct, but “All the above” captures the complete, consolidated practice and is therefore the best choice.

Common Pitfalls:

• Applying only one-side extra ballast on LWR/CWR where both shoulders should be augmented.
• Ignoring site-specific needs such as weak formation or high speeds requiring more stringent profiles.

Final Answer:
All the above