Chords vs Curves

[CyrusWuff]

Down in London, the line between Reading Lane Junction and Navarino Road Junction is known as the Graham Road Curve, and in the West Midlands, the line linking the High Level route with the Trent Valley at Lichfield is known as the Lichfield Trent Valley Chord.

My question is this: What's the difference (if any) between a curve and a chord, and who decides as to whether a given section of line is named as such (and, in some cases, whether it's named at all)?

 

[Busaholic]

Going 'In Search of the Lost Curve' might impart a different meaning to 'In Search of the Lost Chord'!

 

[snowball]

I think we had a thread about this not long ago.

A chord is almost always a curve but a curve is not necessarily a chord. A curve could, for example be anywhere on a long, otherwise straight route with no junctions nearby.

In railway parlance a chord usually means a relatively short line connecting two other lines, so it will normally have junctions at both ends.

In geometry a chord is a straight line segment connecting two points on a circle or other curve.

 

[Starmill]

In geometry a chord is a straight line segment connecting two points on a circle or other curve.

It always struck me as a bit odd that a chord apparently has the inverse meaning on a railway than in mathematics!

Maybe we should refer to it as the Ordsall Segment

 

[Senex]

In railway parlance a chord usually means a relatively short line connecting two other lines, so it will normally have junctions at both ends.

Nowadays yes, but that does seem to be a relatively recent development, replacing the older usage of "curve". Does anyone know when "chord" began to be used in this context?

 

[yorksrob]

It always struck me as a bit odd that a chord apparently has the inverse meaning on a railway than in mathematics!

Maybe we should refer to it as the Ordsall Segment

Wouldn't the Ordsall segment be that area of land bordered by the chord and the railways it links

 

[Gathursty]

We have the Burscough Curves in Lancashire that are two chords no longer in existence but oft-discussed for re-introduction.

I also believe Morpeth curve is mentioned as a restrictive bend on the ECML.

 

[najaB]

Wouldn't the Ordsall segment be that area of land bordered by the chord and the railways it links

Indeed. If anything it would be the Ordsall Arc.

 

[yorksrob]

Indeed. If anything it would be the Ordsall Arc.

That has a nice ring to it !

 

[Joseph_Locke]

That has a nice ring to it !

But geometrically incorrect as it has a variable radius. The right word, I think, is locus.

 

[yorksrob]

But geometrically incorrect as it has a variable radius. The right word, I think, is locus.

That sounds like an insect !

 

[Sunset route]

Down in London, the line between Reading Lane Junction and Navarino Road Junction is known as the Graham Road Curve, and in the West Midlands, the line linking the High Level route with the Trent Valley at Lichfield is known as the Lichfield Trent Valley Chord.

My question is this: What's the difference (if any) between a curve and a chord, and who decides as to whether a given section of line is named as such (and, in some cases, whether it's named at all)?

And south of the river on the old Southern region we call them Spurs, Sydenham Spur, Crystal Palace spur, Selhurst Spur, Lee spur, Brixton spur, Cambria spur, shepperton spur and Kew spur amongst many examples.

 

[snowball]

But geometrically incorrect as it has a variable radius. The right word, I think, is locus.

To a mathematician, "arc" does not necessarily imply a circle. Any connected part of any curve is an arc.

A locus is a set of points satisfying some condition, so could mean almost anything.

 

[30907]

And south of the river on the old Southern region we call them Spurs, Sydenham Spur, Crystal Palace spur, Selhurst Spur, Lee spur, Brixton spur, Cambria spur, shepperton spur and Kew spur amongst many examples.

Kew, Hounslow, Crayford, Sittingbourne and Cliftonville (but the Erith Loop at Barnehurst).

The only other Chord I can think of is Madeley, so is it a localised usage?

 

[70014IronDuke]

Indeed. If anything it would be the Ordsall Arc.

Then, if you saw a train go round it, you could say: "Look, the Arc of a Driver."

(with apologies to the former leader of Traffic) . I'll get my coat.

 

[Joseph_Locke]

The only other Chord I can think of is Madeley, so is it a localised usage?

Would seem so!

 

[Railsigns]

The only other Chord I can think of is Madeley, so is it a localised usage?

Hazel Grove Chord (BR, LMR)
Cowlairs Chord (BR, ScR)
Allington Chord (NR, LNE)

 

[QueensCurve]

Hazel Grove Chord (BR, LMR)
Cowlairs Chord (BR, ScR)
Allington Chord (NR, LNE)

Methinks there has been a change in use over recent years. A "curve" used to connect 2 sides of a triangle whereas this would now be referred to as a "chord". This does seem to have set in with Hazel Grove.

Personally I suggest "curve" is more apt since a "chord", as noted above, is not used in its's mathematical sense.

 

[snowball]

Methinks there has been a change in use over recent years. A "curve" used to connect 2 sides of a triangle whereas this would now be referred to as a "chord". This does seem to have set in with Hazel Grove.

Personally I suggest "curve" is more apt since a "chord", as noted above, is not used in its's mathematical sense.

In the recent thread some 19th century examples of "chords" were found.

 

[QueensCurve]

In the recent thread some 19th century examples of "chords" were found.

The definitely were some, but I think - perhaps wrongly - they were different to the "curves" making up a triangular junction.

 

[ComUtoR]

The only other Chord I can think of is Madeley, so is it a localised usage?

Ravensbourne

 

[Andyjs247]

Chord seems to be the current favourite. Other recently constructed lines include...

Bicester South West Chord
Doncaster North Chord
Nuneaton North Chord

But then I believe the new track at Ipswich is officially the Bacon Factory Curve (rather than Chord).

And then there is also Hitchin Flyover

So not really any consistent rule.

 

[daikilo]

I think the explanation is that a "chord" is a connection between nearby locations on two different routes. It does not describe the actual shape of that connection which could be a "curve", a straight line or a combination of the two.

 

[DarloRich]

But geometrically incorrect as it has a variable radius. The right word, I think, is locus.

will wiggly bit do?

I think the explanation is that a "chord" is a connection between nearby locations on two different routes. It does not describe the actual shape of that connection which could be a "curve", a straight line or a combination of the two.

is the correct answer.

 

[D Foster]

Railway usage - of all sorts of terms - is specific to the railway. Rather than conventional usage such as in maths. The key factor is that people using the term and (in this case) a location know what they are talking about - or, if not, that they stop and ask.

 

[daikilo]

Railway usage - of all sorts of terms - is specific to the railway. Rather than conventional usage such as in maths. The key factor is that people using the term and (in this case) a location know what they are talking about - or, if not, that they stop and ask.

I think that true "railway usage" is actually respectful of maths qnd geometry, the issue is with the "artists" involved in public communications.

 

[GB]

But then I believe the new track at Ipswich is officially the Bacon Factory Curve (rather than Chord).

I think its the other way round. Officially Ipswich chord as per the Network Rail planning and government websites but known as bacon factory curve on the ground.