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Railway Sleepers:

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John Webb

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I think it was mostly by experience from the early days of plateways onwards. No doubt these days there is more science behind it. Presumably train weight and speed determine the weight of rail required and thus the number of sleepers to support train and rail on the ballast bed.
 

furnessvale

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I think it was mostly by experience from the early days of plateways onwards. No doubt these days there is more science behind it. Presumably train weight and speed determine the weight of rail required and thus the number of sleepers to support train and rail on the ballast bed.
Nowadays, another factor is the need to increase lateral restraint to avoid buckling in CWR.
 

Dr Hoo

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Hi, could anyone please tell me, how they determined the spacing between sleepers.
Did you have any particular historical era in mind?
Very simply higher speeds, higher axle loadings and generally higher traffic levels, together with the need for greater restraint on sideways movement (especially for continuous rail on curves) have required a change from 24 sleepers per 60’ to 26 or 28 on many lines.
 

CJK64

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Hi, could anyone please tell me, how they determined the spacing between sleepers.

By the category of track, which is determined by equated million gross tonne per annum and line speed, also the curvature of the track plus any cant deficiency.
I believe it ranges from 600mm to 760mm. Most new installs are either 650mm or 700mm.
 

Ploughman

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By the category of track, which is determined by equated million gross tonne per annum and line speed, also the curvature of the track plus any cant deficiency.
I believe it ranges from 600mm to 760mm. Most new installs are either 650mm or 700mm.

That does not answer the original question.
As those figures are current not Historic.
How did Brunel, Stephenson et al decide on the spacing originally?
Does it come down to a Horses pace stepping between the sleepers or stone blocks?
 

Joseph_Locke

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That does not answer the original question.
As those figures are current not Historic.
How did Brunel, Stephenson et al decide on the spacing originally?
Does it come down to a Horses pace stepping between the sleepers or stone blocks?

Brunel used long timbers initially, not cross sleepers. The Stephensons and myself just followed previous practice: stone blocks would have been spaced at the limit of the length of a cast iron plate, then at the limit of the length of a fishbelly rail
 

CJK64

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That does not answer the original question.
As those figures are current not Historic.
How did Brunel, Stephenson et al decide on the spacing originally?
Does it come down to a Horses pace stepping between the sleepers or stone blocks?

The original question doesn’t state as to when he was referring so it has answered it, anyway They are historic figures.. I laid a new length of track using those spacings LAST WEEK.. that’s historic..
 
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edwin_m

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I seem to recall the original stone blocks didn't have any cross-ties so just relied on their own weight to stay in position. This would have meant there was nothing for a horse pulling wagons to trip over, but presumably a big risk that the gauge would widen under the forces of heavy locomotives.
 

furnessvale

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I seem to recall the original stone blocks didn't have any cross-ties so just relied on their own weight to stay in position. This would have meant there was nothing for a horse pulling wagons to trip over, but presumably a big risk that the gauge would widen under the forces of heavy locomotives.
In the mid 1960s, when I was a perway engineer, I remember reading the American Association of Railways (AAR) standards for track.

On gauge it said, "for 110mph running gauge shall be 4ft 8.5ins, plus or minus half an inch". In other words anything between 4ft 8ins and 4ft 9ins will do.

Perhaps in 1825 gauge was even less important! :)
 

edwin_m

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In the mid 1960s, when I was a perway engineer, I remember reading the American Association of Railways (AAR) standards for track.

On gauge it said, "for 110mph running gauge shall be 4ft 8.5ins, plus or minus half an inch". In other words anything between 4ft 8ins and 4ft 9ins will do.

Perhaps in 1825 gauge was even less important! :)
There was a discussion on another thread about how some US railroads persisted with 4'9" until well into the 20th century, but it was close enough that it could be standardized piecemeal without having to shut the whole line while the track and stock were converted.

Gauge probably was less important in 1825 and I would guess nobody worried about it at all until a train fell off the track, when it would be pushed back on and the stone blocks knocked back into approximately the right place.
 

AndrewE

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I get the impression that the distance between the sleepers (as opposed to between the rails) is down to the strength of the rails and the axle loading.
As said above, originally there was a stone block at the end of each cast-iron fish-belly rail but that soon proved completely inadequate.
Steel rails in cast-iron chairs on sleepers were (are) infinitely better so we have our traditional bull-head track, as seen on heritage railways.
Flat-bottomed rail has got heavier and heavier (i.e. thicker and thicker section) over the years, and pictures of some really heavy-haul railways in Europe and the USA seem to have the concrete sleepers supporting 50% of the rail foot (- although that could be the effect of a telephoto lens!) In the UK there seems to be about 2 sleepers' width between them...
I'm surprised that nobody has pointed us at a UK spec for axle weights, rail grades and sleeper spacing...
 

PaxVobiscum

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Very simply higher speeds, higher axle loadings and generally higher traffic levels, together with the need for greater restraint on sideways movement (especially for continuous rail on curves) have required a change from 24 sleepers per 60’ to 26 or 28 on many lines.

[CONSPIRACYTHEORY] A likely story!
We all know that this is simply to make the railway look longer just like it used to be before they decided to shorten our fine British railway by reducing the number of route miles. [/CONSPIRACYTHEORY]
 

Daniel Pyke

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The spacing between sleepers is a combination of factors, but axle load and rail height (profile) are the two primary factors.
Axle loads in the UK rarely exceed 25t, (unless you work where I do!). Axle loads elsewhere in the world are higher (30t+). In order for the rails not to fatigue (and break) you need to stay below a limiting stress. To reduce this stress you either put the rail supports (sleepers) closer together, or make the rail taller, (or both). Or if you look at it the opposite way to keep the same stress with heavier axle loads you need taller rails and/or sleepers spaced more closely together. That's why tramways only need dinky little rails and freight railways use much bigger ones.
 

Ships

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The spacing between sleepers is a combination of factors, but axle load and rail height (profile) are the two primary factors.
Axle loads in the UK rarely exceed 25t, (unless you work where I do!). Axle loads elsewhere in the world are higher (30t+). In order for the rails not to fatigue (and break) you need to stay below a limiting stress. To reduce this stress you either put the rail supports (sleepers) closer together, or make the rail taller, (or both). Or if you look at it the opposite way to keep the same stress with heavier axle loads you need taller rails and/or sleepers spaced more closely together. That's why tramways only need dinky little rails and freight railways use much bigger ones.

In the Uk axle load has no bearing on this. Highest axle loads tend to be on the lower track categories (lower line speeds) where wider centres are required. I would guess this has more to do with the lower dynamic forces at lower speeds
 
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