Quote:
Originally Posted by s211
I'm curious why the Canada Line southbound of the Yaletown station slows to a crawl as it approaches the line's lowest point and then guns it uphill afterward. The northbound section doesn't do that.
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This is a Google AI response, so don't shoot the messenger if it's wrong...
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The speed difference on the Canada Line between Yaletown-Roundhouse and Olympic Village is primarily due to the specific track geometry required to cross under False Creek and the technical constraints of the line's design.
Reasons for Southbound Speed Reduction
Steep Descent and Gradients: Southbound trains departing Yaletown-Roundhouse must descend significantly to pass through the bored tunnel under False Creek. To ensure safety and control, the automated SelTrac signaling system enforces lower speeds on steep downward grades.
Tight Curvatures: The transition from the downtown bored tunnels to the "cut and cover" section near Olympic Village involves curves that limit speed to prevent excessive wheel and rail wear. These curves are often restricted to lower speeds compared to the straighter approaches into Yaletown from the north.
Operational Headway: Southbound trains are often managed more strictly to maintain proper spacing (headway) before the line splits toward YVR-Airport and Richmond-Brighouse. If a train ahead is slightly delayed at the merge point, following southbound trains will automatically slow down.
Why Northbound Appears Faster
Uphill Momentum: Northbound trains are climbing toward Yaletown. The system may allow for a different power profile to maintain momentum on this ascent, making the approach feel more aggressive.
Station Layout: Yaletown-Roundhouse uses a stacked platform or split-level layout in some sections, which affects how trains enter the station from different directions. Northbound trains may have a longer, straighter run-in to the platform compared to the immediate curves encountered when heading southbound.
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