Where is the standard rail cant (tilt) of 1 in 20 provided in track construction?
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AAt the rail seats in bearing plates, chairs, and metal sleepers (not on the rail head itself)
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BOn the top (running surface) of the rail head
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COnly at joints, not under through sleepers
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DOnly on curves with cant > 100 mm
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EAt ballast surface by trimming shoulders
Answer
Correct Answer: At the rail seats in bearing plates, chairs, and metal sleepers (not on the rail head itself)
Explanation
Introduction / Context:Rails are canted inward at 1 in 20 to align wheel–rail contact near the rail head center, reducing wear and improving stability. Understanding where and how this inclination is implemented is important for design and maintenance.
Given Data / Assumptions:
- Cant 1 in 20 is standard for BG flat-bottom rails.
- Cant is achieved by inclined rail seats or fittings, not by tilting the running surface of the rail head itself.
Concept / Approach:
The inclination is built into the support components (chairs, bearing plates, or sleeper seats) so that the rail is installed at the required angle. The rail head remains a manufactured profile; its running surface is not machined to provide cant.
Step-by-Step Solution:
Identify the purpose of cant: better flange/rail contact.Locate where cant is introduced: at the seats/fastenings.Conclude: provided at rail seats on sleepers/chairs/plates.Verification / Alternative check:
Standard drawings show inclined rail seats; fastening systems (e.g., Pandrol clips with baseplates) preserve the 1 in 20 inclination.
Why Other Options Are Wrong:
Top of rail head is not where cant is formed; limiting to joints or only very high cants is incorrect; ballast trimming cannot provide precise inclination.
Common Pitfalls:
Assuming the rail profile itself is tilted by milling; overlooking that PSC sleepers often have cast-in inclined seats.
Final Answer:
At the rail seats in bearing plates, chairs, and metal sleepers (not on the rail head itself)