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Zero point for mileage on the Ungerground.

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Gloster

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As here - from Watford to Ricky starts at Watford at km 76.08, km descending to Croxley 74.10 and Watford E Jn 73.26. Where the kmage changes to 72.80, and increases to Watford N Jn 73.35 (matching kmage up the 'main line' from Baker St and Watford S Jn), Ricky 74.52 and on.

Remember these km figures are arbitrary progessive distances along the line, not really measured from anywhere in particular.
Aren’t all distances on the underground measured from a zero point at the buffer stops at Ongar. The transfer from the Central to the sub-surface lines takes place at Mile End, which means that for Mile End-Upminster the distances are counting down.
 
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etr221

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Aren’t all distances on the underground measured from a zero point at the buffer stops at Ongar. The transfer from the Central to the sub-surface lines takes place at Mile End, which means that for Mile End-Upminster the distances are counting down.
While LU kilometrages (for ex LT lines) are based on a datum of 0.0 at Ongar buffer stop, except for the Central Line to Ealing Broadway and West Ruislip, it is somewhat misleading and confusing to describe them as 'distances from', or 'measured from', Ongar. The Central 'main line' kilometrages (which are progressive from Ongar) at Loughtonstone Junction and Mile End as used as datums for the Hainault loop (kms descending round to Woodford) and District Line; and from the District Line figures you get a datum for the Piccadilly; and so on as kmages propogate round the system.

The system was devised with two aims - to avoid negative kilometrages, and minimise the number of 'jumps'; CULG has a brief description, while the railwaycodes distances diagram lists transfer points (where kilometrage on one line provides datum for another)
 

Mojo

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As here - from Watford to Ricky starts at Watford at km 76.08, km descending to Croxley 74.10 and Watford E Jn 73.26. Where the kmage changes to 72.80, and increases to Watford N Jn 73.35 (matching kmage up the 'main line' from Baker St and Watford S Jn), Ricky 74.52 and on.
I’m assuming those distances are ones you’ve taken from CULG? As mentioned above the official source I have shows East Junction as at 73.32km and North Junction as 73.41km.

The meterage doesn’t change at East Junction if heading toward the South Curve (eg. the public footpath footbridge over the curve is at 73km). To answer @jumble’s question, hopefully my answer several posts above should explain why.
 

etr221

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I’m assuming those distances are ones you’ve taken from CULG? As mentioned above the official source I have shows East Junction as at 73.32km and North Junction as 73.41km.

The meterage doesn’t change at East Junction if heading toward the South Curve (eg. the public footpath footbridge over the curve is at 73km). To answer @jumble’s question, hopefully my answer several posts above should explain why.

As here - from Watford to Ricky starts at Watford at km 76.08, km descending to Croxley 74.10 and Watford E Jn 73.26. Where the kmage changes to 72.80, and increases to Watford N Jn 73.35 (matching kmage up the 'main line' from Baker St and Watford S Jn), Ricky 74.52 and on.

Remember these km figures are arbitrary progessive distances along the line, not really measured from anywhere in particular.
Seems you can't rearrange quotes....

But yes, figures I gave came from CULG. To clarify, perhaps what I should have written, "Where the kmage changes to 72.80, going round to Watford N Jcn, and..."
 
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