Q: Why are some spikes painted with colored heads?
A: Colored paint on spike heads is often used for identification and maintenance purposes. A specific color can indicate the year of installation, the maintenance crew that installed it, or a specific track section. This provides a simple visual aid for inspectors to track maintenance history and identify spikes that may need inspection or replacement.
Q: What are the common failure modes of a rail spike?
A: Common failure modes include:
Corrosion: Thinning of the shank, leading to breakage.
Loosening ("Spike Kill"): Loss of grip in the sleeper.
Shearing: The head shearing off due to excessive lateral force.
Bending: Deformation from improper installation or removal.
Q: How does a spike fastening system compare to a clip fastening system?
A: Spike systems (especially cut spikes) are simpler and cheaper initially but generally provide less restraint, especially against longitudinal rail movement (creep). Modern elastic clip systems offer superior holding power, maintain constant tension, are better for preventing creep, and are the standard for high-speed and heavy-haul railways. Spikes remain prevalent on secondary lines and with wooden sleepers.
Q: What special precautions are needed for spikes in electrified railway corridors?
A: In electrified zones, especially with third rails or where stray currents are a concern, spikes must be inspected to ensure they do not create unintended electrical paths that could lead to electrolytic corrosion. The integrity of their insulation from the ground is more critical.
Q: How are spikes packaged for shipping and storage?
A: Spikes are heavy and are typically packaged in sturdy wooden crates or heavy-duty sacks to prevent damage during transport. They are often bundled in weights manageable for manual handling (e.g., 50 kg). Proper storage indoors or under cover is essential to prevent premature corrosion of the coating before installation.