Railway Gauge

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cirdan

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This one (their statement of the origin of track gauge comes from the width of a horse's butt) comes up often with variations. Think wagon wheels set on 5 feet centers with 4 inch wide iron treads. That leaves you 4 feet 8 inches. Put a vertical flange on the inside of the wheel Make the rails an additional 1/2 inch further apart so that you have a little play, and guess what! You get 4 feet 8 1/2 inches. I suspect this to be the most likely origin.
I'm not sure.

George Stephenson built the Stockton & Darlington to this gauge because this was the gauge he was accustomed to from the colliery where he had previously been employed and where he first experimented with building locomotives. At the time every colliery had its own gauge. Had Stephenson been employed elsewhere he would probably have adopted whatever gauge they had there. Trevithick for example built to a narrower gauge for much the same reason. If you want to dig into the reason any particular gauge was used in any place, there is typically no record, and in all likelihood the initial decision was taken on the fly by whatever local blacksmith had been asked to install the first tracks and supply the first coal cars. Subsequent generations just copied that.

There have been horse- drawn colliery and quarry lines that used gauges significantly narrower than 4'8 1/2". This wasn't a problem for the horses. Today we have a concept of a horse that is a thoroughbred and large and heavy animal with a fiery temprament and that will gallop at high speeds and effortlessly jump over hedges. Back in the day the cavalry may have had such horses and a couple of rich folks may have used them for hunting and racing. The animals that went into the mines were often more ponies and mules and small mangy horses as well as various indeterminate cross-breeds that could be bought and maintained on a low budget. There were mining operations that used what they called horses on gauges as small as 2 foot.

Anyway, it's not the width of a horse's butt that is in any way relevant for the track gauge, but the distance between its hoof prints, which is typically a fair bit smaller than the width of the butt.
 

JontyMort

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Conversely British loading gauge is much smaller than AAR loading gauge, while both run on standard gauge tracks. There are a few routes in the UK cleared for the Continental UIC loading gauge, but none for any AAR loading gauge AFAIK.
In practice, only the high speed line between London St Pancras International and the Channel Tunnel is cleared to UIC gauge. The original Eurostar sets had to run on classic lines and were a compromise. The Siemens E320 sets use the extra gauge, I believe.
 
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cirdan

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In practice, only the high speed line between London St Pancras International and the Channel Tunnel is cleared to UIC gauge. The original Eurostar sets had to run on classic lines and were a compromise. The Siemens E320 sets use the extra gauge, I believe.
There was once a railway called the Great Central which was the last mainline trunk route of any greater length to be built in Britain until HS1. It was built to European clearances in anticipation of wider trains and ran from London Maryelbone up north via Sheffield to Manchester.

The same people who built it were also behind the first Channel Tunnel project. It would thus have formed part of a grand plan to bring European sized trains to Britain. This was never to be.

In a short-sighted move in the 1960s, the line was closed and dismantled (with the exception of a few short sections).

There was a privately backed proposal about 20 years ago to reopen it as a freight corridor to bring European sized freight trains to the north. This project was eventually dropped.

A shortish stub at the London end is still used for commuter trains today. In Nottingham part of the alignment is now used by trams. There is also a short section that is used for freight and two sections that were restored as heritage lines with a project currently underway to connect them.

The rest of the line will probably never return and has been built on in many places.
 

jis

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Even where routes built originally to much larger loading gauge exist today in their entirety they do not have clearances for larger than British standard loading gauge today. There is very little incentive to maintain gauges which are unlikely to be used much, specially before the Eurotunnel was built. Of course no one was sure that the thing would actually get built and put into service given Margaret Thatcher's antics.

At present the plan is to upgrade the Midland Main Line to the so called GC gauge to allow continental loading gauge freight trains (UIC C) to travel minimally upto the vicinity of Sheffield. MML is a good choice since its London end is at St. Pancras which is where HS-1 built to GC gauge terminates at present.

AFAICT HS-2 is also being built to GC gauge. I suppose there already is GC access to Wembley Yard somehow (I don’t know the details) HS-2 of course will terminate at Euston, but I believe there is a GC gauge connection from St. Pancras to the vicinity of Euston, which is how GC gauge freights get to Wembley. But this is all from vague memory so could be wrong.
 
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JontyMort

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There was once a railway called the Great Central which was the last mainline trunk route of any greater length to be built in Britain until HS1. It was built to European clearances in anticipation of wider trains and ran from London Maryelbone up north via Sheffield to Manchester.

The same people who built it were also behind the first Channel Tunnel project. It would thus have formed part of a grand plan to bring European sized trains to Britain. This was never to be.

In a short-sighted move in the 1960s, the line was closed and dismantled (with the exception of a few short sections).

There was a privately backed proposal about 20 years ago to reopen it as a freight corridor to bring European sized freight trains to the north. This project was eventually dropped.

A shortish stub at the London end is still used for commuter trains today. In Nottingham part of the alignment is now used by trams. There is also a short section that is used for freight and two sections that were restored as heritage lines with a project currently underway to connect them.

The rest of the line will probably never return and has been built on in many places.
It is frequently stated that the GC was built to a more generous loading gauge, but this is actually an urban myth.

The Channel Tunnel aspirations of Sir Edward Watkin were real enough, however.

As you say, restoration of the line north of Ashendon Junction would be all but impossible. It was very heavily engineered through Rugby, Leicester and (especially) Nottingham, and all the infrastructure has been destroyed or re-used.
 

John819

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I believe that way back the Southern Railway had a 5 foot gauge that was then modified in the 1880s to the US standard.
 

George Harris

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Most of the railroads in the South were to 5'-0" gauge before the War Between the States and in most cases until the 1870's or 80's. One more example that winners write the rules.
 
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