Timber sleeper suitability: What is the minimum composite sleeper index (CSI) prescribed for wooden sleepers used in cross-overs on Indian Railways?

Introduction / Context:
The composite sleeper index (CSI) is a measure combining strength and durability parameters of timber to assess its suitability as a sleeper. Cross-overs experience complex loadings from turnouts and crossings; thus a higher minimum CSI is specified.

Given Data / Assumptions:

• Application: wooden sleepers for cross-overs (turnout zones).
• CSI thresholds vary by location severity: plain track vs. points & crossings.

Concept / Approach:
Heavier impact and lateral forces at cross-overs demand higher-quality timber. A commonly prescribed minimum CSI for such locations is higher than for plain track to ensure adequate life and resistance to splitting and wear.

Step-by-Step Solution:
Recognize cross-over sleepers require better timber class.Select the threshold CSI used for points & crossings.Adopt 1352 as the minimum CSI for wooden sleepers in cross-overs.

Verification / Alternative check:
Track maintenance manuals list higher CSI benchmarks for special locations compared to plain track.

Why Other Options Are Wrong:

• 1152, 1252: Suitable for lighter duty; below cross-over requirement.
• 1452: Acceptable but not the minimum; represents a higher grade.
• None of these: Incorrect since a standard minimum exists.

Common Pitfalls:
Using plain-track CSI for special locations; overlooking increased dynamic effects at crossings.

Final Answer:
1352