Automatic railway signaling systems monitor train locations by sending a continuous low-voltage electrical current through the steel rails to an energized track relay. When a train enters a designated track block, its steel axles conduct electricity between the rails, creating a short circuit that deprives the relay of current and triggers a red stop signal. Railway track beds are layered with crushed granite ballast specifically to drain water away and preserve electrical insulation between the two rails. During severe weather, standing water mixed with conductive mineral silt can pool over compromised ballast and bridge the rails.
Based on the passage, what is the implied consequence of conductive water bridging the rails?
- AThe track relay will remain continuously energized because the granite ballast drains standing water.
- The signaling system will indicate that the track section is occupied even if no train is present.Cevap
- CThe granite ballast will immediately lose structural integrity and cause track collapse.
- DThe train wheelsets will be prevented from conducting electrical current between the tracks.
Cevap
The signaling system will indicate that the track section is occupied even if no train is present.
The passage states that a red signal is triggered whenever electricity is conducted between the rails to short-circuit the track relay, such as when steel axles cross them. If conductive mineral water bridges the rails, it performs the same electrical function as an axle, shorting the circuit and causing the system to display a false occupied (stop) indication.
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Identifying Implied Meanings
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