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Ruling gradient

node

The steepest sustained grade on a section of line, and the number that governs everything else about it. Because a train must be able to climb the worst piece of the route unaided, the ruling gradient fixes the minimum locomotive power or the maximum train weight for the whole run — the weakest-link property that makes one hill the arbiter of a thousand kilometres of flat track. Railways buy their way out of it in only three ways: more power on the front, helper locomotives stationed at the hill, or civil engineering that removes the grade. The Canadian Pacific tried all three at Kicking Horse Pass, and the last one — the Spiral Tunnels, taking 4.4 to 4.5 per cent down to 2.2 — is the one that stuck. This is why alignment is the expensive, permanent part of a railway and rolling stock is the cheap, replaceable part.

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Assembled narrative · 1

Assembled from 21 blocks · 1 evidence · 32 related

  1. Story
  2. The steepest sustained grade on a section of line, and the number that governs everything else about it. Because a train must be able to climb the worst piece of the route unaided, the ruling gradient fixes the minimum locomotive power or the maximum train weight for the whole run — the weakest-link property that makes one hill the arbiter of a thousand kilometres of flat track. Railways buy their way out of it in only three ways: more power on the front, helper locomotives stationed at the hill, or civil engineering that removes the grade. The Canadian Pacific tried all three at Kicking Horse Pass, and the last one — the Spiral Tunnels, taking 4.4 to 4.5 per cent down to 2.2 — is the one that stuck. This is why alignment is the expensive, permanent part of a railway and rolling stock is the cheap, replaceable part.
  3. Knowledge
  4. Ruling gradient
  5. The main-line steam locomotive
  6. Connections
  7. Trans-Siberian Railway
  8. Canadian Pacific transcontinental main line
  9. The main-line steam locomotive
  10. The last spike is driven at Craigellachie
  11. The Spiral Tunnels open and the Big Hill is retired
  12. The Severomuysky Tunnel opens under the BAM's worst obstacle
  13. Liverpool and Manchester Railway
  14. The Rainhill trials settle the question of traction
  15. Trans-Siberian Railway
  16. Ruling gradient
  17. Coal
  18. The through sleeping car
  19. Electrification of the Trans-Siberian is completed
  20. Evidence
  21. Supports the Big Hill's original grade of about 4.4–4.5 per cent over Kicking Horse Pass and its reduction to 2.2 per cent by the Spiral Tunnels, built 1907–1909. V55 verification basis: the Parks Canada page was returned in search but not fetched; the grade figures and the 1 September 1909 opening were carried in accompanying Canadian rail-history summaries and differ between sources on 4.4 versus 4.5 per cent.
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/atlas?object=CONCEPT_RULING_GRADIENT&experience=CONCEPT_RULING_GRADIENT