Why 4’8 1/2”?

[BanburyBlue]

Evening all. Just watching Michael Portillo’s great European Railway Journeys with Mrs BanburyBlue. We’re in Greece (on the tv, not in reality) and there’s a section of antique Roman track. I remember something in the back of my mind that said in Roman times they found railway type tracks, horse drawn carts etc, that were 4’ 8 1/2”.

so, the question is, why 4’ 8 1/2” - it seems a random measurement?

thanks

 

[WestCountry]

4' 8½" became the standard from being adopted for the Liverpool & Manchester Railway, which was the first 'real' mixed-use long-distance railway and quickly extended in various directions.

Originally it was 4' 8", copied from the Stockton & Darlington Railway, the extra ½" was found to reduce friction on curves with existing wheelsets.

All sorts of gauges around 4-5ft were used on early wagonways, plateways and railways. Some survive to the present, like 5' in Russia and 5' 3" in Ireland.

That general range of 'gauge' was common for both wagonways and road carts, because it's a bit wider than a horse which is convenient for mounting shafts either side (and in case of a railway, not having the horse step on the rails). It's a myth that the specific 4' 8½" measurement had any significance before the railways.

 

[Chester1]

Evening all. Just watching Michael Portillo’s great European Railway Journeys with Mrs BanburyBlue. We’re in Greece (on the tv, not in reality) and there’s a section of antique Roman track. I remember something in the back of my mind that said in Roman times they found railway type tracks, horse drawn carts etc, that were 4’ 8 1/2”.

so, the question is, why 4’ 8 1/2” - it seems a random measurement?

thanks

The Roman thing is an urban myth that remains popular. GB uses 4ft 8 1/2 inches because it's the width that was used for tracks inside the mines that the Stockton and Darlington railway was built to serve and it out competed Brunel's broad gauge.

Edit: slightly beaten to it and corrected by @WestCountry I wasn't aware that half an inch was added for Liverpool and Manchester Railway.

 

[hexagon789]

Edit: slightly beaten to it and corrected by @WestCountry I wasn't aware that half an inch was added for Liverpool and Manchester Railway.

Similar was done with Brunel's Broad Gauge for exactly the same reason - it was originally exactly 7ft but eased 1/4in to give smoother running in curves.

 

[Dr Hoo]

It is worth being clear that the gauge of the early waggonways in North East England was effectively dictated by the unit of measurement known as the chaldron. This was strictly a unit of volume rather than weight but in the days before large scale weighing was feasible was the obvious way of calculating tolls, duties, shipping charges and so on.
Back in the 1600s a chaldron was set as the maximum size of a horse-drawn road vehicle in order to prevent undue damage to the primitive roads of the time. Given the state of the roads in terms of surface and profile such a load would need to be hauled by more than one horse anyway. Wainwrights were used to making ‘chaldron’ wains for the roads so it was fairly inevitable that rail waggons would be made the same size.
It is worth noting that in other parts of the country Benjamin Outram engineered hundreds of miles of cast iron plateway with a gauge of 4’ 2” and these worked perfectly happily with a horse between the shafts. Some of his early plateways were only 3’ 6” but these worked fine with horse haulage too.
The idea that 4’ 8.5” was dictated by the dimensions of a horse’s posterior is a complete and utter myth that just will not die, but is continually trotted out by authors, journalists and commentators who are simply insulting their audiences.

 

[hwl]

Originally it was 4' 8", copied from the Stockton & Darlington Railway, the extra ½" was found to reduce friction on curves with existing wheelsets.

4'8" is 14 hands in more traditional/ancient imperial measures e.g. a nice round number

 

[LYradial]

I was always led to believe that originally the measurement was 5 feet to the outside of the rails, to stop the wheels falling between the rails, only when inside flanges and switches and crossings were introduced did the ‘between the rails’ measurement become important

 

[DarloRich]

so, the question is, why 4’ 8 1/2” - it seems a random measurement?

Because Darlington!

Is it not the width of the chauldron wagon used in the mines?

The idea that 4’ 8.5” was dictated by the dimensions of a horse’s posterior is a complete and utter myth that just will not die, but is continually trotted out by authors, journalists and commentators who are simply insulting their audiences.

or it is a nice folk tale to include as a bit of colour - surely the real answer is we don't actually know! We have some strong assumptions but no actual proof.

 

[Ashley Hill]

Is it 4’ 8 3/8” on flat bottom rail? I seem to remember being told that on my training course far to many years ago.

 

[mike57]

Another early railway which doesn't get much coverage, the Surrey Iron Railway, was a 'plateway' with a 4ft 2in gauge. It was a public railway, horse drawn, my understanding is anyone could use if they paid the tolls and had the required wagons. I assume the gauge would have been suitable for wagons already in use in the area.

Like a lot of things something which started as a local undertaking spread key parts of its technology to the rest of the country, I suspect that the 4-5ft range for gauge was probably because this resulted in wagons which had sufficent capacity to be useful, but were not too heavy to be horse drawn.

In the early days 4ft 8in wasnt the standard, the Eastern Counties Railway (precursor to the Great Eastern) started with 5ft gauge until 1844. There were also a number similar but not identical gauges in Scotland, and of course the Glasgow Subway is still 4ft gauge.

Brunels broad gauge was conceived as a steam operated railway from the outset, and you could argue that the 7ft gauge was the right choice from an engineering viewpoint, but was flying in the face of what was rapidly becoming a standard. A good modern example would be the Betamax v VHS format wars. Betamax was the better system but VHS won out because of wider adoption.

 

[edwin_m]

Back in the 1600s a chaldron was set as the maximum size of a horse-drawn road vehicle in order to prevent undue damage to the primitive roads of the time. Given the state of the roads in terms of surface and profile such a load would need to be hauled by more than one horse anyway. Wainwrights were used to making ‘chaldron’ wains for the roads so it was fairly inevitable that rail waggons would be made the same size.

Some of the earliest "railways" had L-shaped rails and no wheel flanges, which allowed wagons of the correct width to run on the roads as well.

Is it 4’ 8 3/8” on flat bottom rail? I seem to remember being told that on my training course far to many years ago.

Sometime around 1980 BR reduced the gauge from 1435mm to 1432mm for new track. I think this was the civil engineers' response to excessive lateral oscillation or "hunting" of bogie stock at high speeds. However, the mechanical engineers were looking to solve the same problem by changing the wheel profile, and the one they came up with was optimised for 1435mm and worse on 1432mm. According to Modern Railways magazine at the time, the Selby Diversion was laid to the narrower gauge, resulting in rough riding on a brand new line. New track reverted to the original gauge sometime later, but there is probably still some of the narrower stuff out there.

Brunels broad gauge was conceived as a steam operated railway from the outset, and you could argue that the 7ft gauge was the right choice from an engineering viewpoint, but was flying in the face of what was rapidly becoming a standard. A good modern example would be the Betamax v VHS format wars. Betamax was the better system but VHS won out because of wider adoption.

I remain unconvinced that it was the best choice at the time. For example with a wider track gauge flange contact will start to happen on a less tight curve, so broad gauge may have been ideal for the original London-Bristol route but became less so as it extended into more difficult terrain.

With hindsight I'd say that Stephenson got it about right. 1435mm can handle the highest speeds, and the reasons not to go faster have nothing to do with track gauge. Although a wider track gauge might allow wider wagons, the loads can't be increased in proportion because the extra axle load would start deforming the rails, and even non-weight-critical passenger stock will have a higher axle load making it less suitable for high speeds.

 

[waverley47]

With hindsight I'd say that Stephenson got it about right. 1435mm can handle the highest speeds, and the reasons not to go faster have nothing to do with track gauge. Although a wider track gauge might allow wider wagons, the loads can't be increased in proportion because the extra axle load would start deforming the rails, and even non-weight-critical passenger stock will have a higher axle load making it less suitable for high speeds

Just to add as well that 26m long coaches are pretty much maxing out the practical length of rolling stock, so you gain nothing by having a wider gauge beyond the cost of converting vast swathes of the country to a wider gauge.

 

[Big Jumby 74]

Just to add as well that 26m long coaches are pretty much maxing out the practical length of rolling stock, so you gain nothing by having a wider gauge beyond the cost of converting vast swathes of the country to a wider gauge.

Slightly OT, but you are correct. Take Waterloo throat, 23m vehicles (442 originally, 444 latterly) have restrictions placed on them route wise, entering/departing the station if the Main Slow lines are involved due to the track curvature. Not, I hasten to add relating to the track itself, but due to clearance issues with other trains due to the compact nature of the overall track layout. Sure there must be other locations that still have the same sort of (historical) restrictions?

 

[mike57]

1435mm can handle the highest speeds

Interesting thought, how much narrower would the gauge have to get before speeds were limited due to the gauge. 4ft 81/2 inch has been tested upto over 350mph by SNCF, and the track was new but standard, although there were a lot of other tweaks to get to this speed, higher catenary voltage and larger wheels are two that come to mind. There are regular 200mph or a bit more services in various countries. So assuming you wanted to acheive 200mph but didnt want to go any faster and wanted to use standard flanged wheel on rail.

Would the 4ft 8in railways during the 1840s have been able to support the speeds that the GWR was acheiving on 7ft? The designs and engineering was much simpler?

I find the whole area of how railways developed interesting.

Some of the earliest "railways" had L-shaped rails and no wheel flanges, which allowed wagons of the correct width to run on the roads as well.

I think that was the principle of the Surrey Iron Railway

 

[edwin_m]

Interesting thought, how much narrower would the gauge have to get before speeds were limited due to the gauge. 4ft 81/2 inch has been tested upto over 350mph by SNCF, and the track was new but standard, although there were a lot of other tweaks to get to this speed, higher catenary voltage and larger wheels are two that come to mind. There are regular 200mph or a bit more services in various countries. So assuming you wanted to acheive 200mph but didnt want to go any faster and wanted to use standard flanged wheel on rail.

I don't know, but I believe the maximum speed on a narrower gauge is about 100mph on the Japanese classic network. Notably the Japanese adopted 1435mm for their high speed network despite having no other track of that gauge that they had to connect to.

 

[12LDA28C]

Brunels broad gauge was conceived as a steam operated railway from the outset, and you could argue that the 7ft gauge was the right choice from an engineering viewpoint, but was flying in the face of what was rapidly becoming a standard. A good modern example would be the Betamax v VHS format wars. Betamax was the better system but VHS won out because of wider adoption.

As I understand it, Brunel chose broad gauge primarily as he considered it safer due to the lower centre of gravity of the wider railway vehicles which resulted in them being more stable at higher speeds.

 

[mike57]

Notably the Japanese adopted 1435mm for their high speed network despite having no other track of that gauge that they had to connect to.

That would imply that they 'knew' that they couldn't get higher speeds out of 3ft 6in back in the 60s. Quite an interesting topic... Mind you by this point the French had already got to 200mph but I believe the rolling stock instability pretty well destroyed the track and nearly ended in disaster. Also the story that on one of the first A4 high speed runs the engine proved capable of 110mph plus but the carriages were not up to it.

 

[birchesgreen]

What is quite fascinating (and definitely mad) is the Nazi plan for a broad gauge network for the thousand year (ho ho) Reich. This was to be 3000mm, though originally was planned to be 4000!

More info if you are interested: https://en.wikipedia.org/wiki/Breitspurbahn

 

[Peter Wilde]

The argument that a gauge of 4ft plus was needed for horse haulage may have been put forward at the time, but doesn’t stand up to subsequent experience. Look at the Festiniog for example - just under 2ft gauge, designed for gravity haulage downhill, horse haulage uphill (which apparently worked OK for reasonably long trains of empty slate wagons).

 

[duffield]

What is quite fascinating (and definitely mad) is the Nazi plan for a broad gauge network for the thousand year (ho ho) Reich. This was to be 3000mm, though originally was planned to be 4000!

More info if you are interested: https://en.wikipedia.org/wiki/Breitspurbahn

That's totally insane. The picture of the model carriage next to a normal coach (and the proposed dimensions) show something literally the size of a large two storey house on wheels!

Interesting that the gauge did have one sane reason behind it - the width of the sleeperless track meant it could double as a road.

It's a shame that at least one section wasn't built and then later preserved as an extraordinary mechanical folly. In addition to the ludicrously huge rolling stock, the civil engineering involved would have been something to behold.

 

[edwin_m]

That's totally insane. The picture of the model carriage next to a normal coach (and the proposed dimensions) show something literally the size of a large two storey house on wheels!

Interesting that the gauge did have one sane reason behind it - the width of the sleeperless track meant it could double as a road.

It's a shame that at least one section wasn't built and then later preserved as an extraordinary mechanical folly. In addition to the ludicrously huge rolling stock, the civil engineering involved would have been something to behold.

I read somewhere that it wasn't actually a practical possibility, possibly due to the axle load issue I mentioned above, but the engineers involved carried on working on it to avoid being sent to the front or worse.

The argument that a gauge of 4ft plus was needed for horse haulage may have been put forward at the time, but doesn’t stand up to subsequent experience. Look at the Festiniog for example - just under 2ft gauge, designed for gravity haulage downhill, horse haulage uphill (which apparently worked OK for reasonably long trains of empty slate wagons).

It seems more likely to have been what others have suggested, that standard gauge was chosen to allow wagons to be the same size as the road carts in use at the time, which were probably the largest that could practically be moved by a single horse.

Was there a tradition of small slate wagons that led to the Ffestiniog being the gauge it was, or it was just to reduce costs by enabling a narrower formation and tighter curves? It must be one of the very few early railways that didn't have a track gauge of between 4ft and 5ft.

 

[Bald Rick]

Aha. This allows me to wheel out, again, my favourite railway fact:

To three decimal places….

Standard gauge is Pi/2 yards
Broad gauge is Pi-1 metres


Obviously Brunel went Metric due to his French heritage.

 

[Merle Haggard]

Scanning through old accident reports in the excellent Railways Archive I sometimes find out interesting facts...

Relevantly to this thread, the report of the accident between South Wingfield and Ambergate on the North Midland Railway on 13tb September 1840 stated that the gauge of that line was 4' 9". The train included some London & Birmingham railway coaches of 4' 8 1/2" gauge and this may have been a factor in the derailment.

Also I think I remember correctly reading that the lines in the states that seceded to the Confederate States of America had a slightly wider gauge than 4' 8 1/2".

 

[edwin_m]

Also I think I remember correctly reading that the lines in the states that seceded to the Confederate States of America had a slightly wider gauge than 4' 8 1/2".

Yes, I believe various gauges were used, mostly wider than standard. Also they tended to be links from ports to their hinterlands rather than making overland connections, so the Confederacy was much less able to manage logistics especially when the Union blockaded their ports.

 

[brad465]

Sounds like Darlington deserves some huge royalties for being home to the widespread gauge adoption around the world (unless it's technically now in the public domain)

 

[Merle Haggard]

The following is probably one of those 'good stories with no foundation on fact' but...
I was told by another railwayman long ago that the builders of the Panama Canal Railway were worried about invasion, which they thought would be made easier if it was built to Standard Gauge. They instead built it to 5' gauge. Of course, that was also the gauge of Russian railways; and as a further twist, the latter chose it to make invasion more difficult.

 

[Calthrop]

The following is probably one of those 'good stories with no foundation on fact' but...
I was told by another railwayman long ago that the builders of the Panama Canal Railway were worried about invasion, which they thought would be made easier if it was built to Standard Gauge. They instead built it to 5' gauge. Of course, that was also the gauge of Russian railways; and as a further twist, the latter chose it to make invasion more difficult.

A new one on me; but as as they say, anything's possible !

I've hitherto understood that the Panama Railroad's original -- opened 1855 -- gauge being 5': came about simply because gauge-standardisation on four-eight-and-a-half took a long time to happen in the USA; and in the earlier days of railroads there, 5' was one of the more favoured gauges (especially in what became briefly, the Confederacy). Choice of that gauge for the US-promoted-and-realised Panama line would thus have been unsurprising, irrespective of any strategic considerations.

E.T.A.: re @Merle Haggard's earlier post #23, and @edwin_m's post #24 (points which I missed earlier) -- in the early / mid 19th century US, the rather predominant gauge in the "Confederate States" area was, by my understanding, 5' -- thus, significantly wider than four-eight-and-a-half; but by no means universal there. As @edwin_m mentions, this was unhelpful to the Confederacy in the Civil War; in the "North" at the time, four-eight-and-a-half tended to predominate, but was far from ubiquitous. It seems that this situation was less acute up north; and/or those concerned there, managed to cope with it better, than did their Confederate counterparts.

 

[ThirteenArches]

The real reason for 1435mm is that that was the gauge of the Willington waggonway was 1435mm, as was the Kenton and Coxlodge and the Bigges Main Line waggonway. These were all linked (not necessarily all simultaneously) as something of a single network. And George Stephenson't father worked at Killingworth, so he got a job there which enabled him to show his sound grasp of steam technology. He naturally used his connections later to allow him to test out new locomotives at Killingworth before deploying them on other lines, and to allow this he built the new lines to the same gauge. 4'8" or the extra half, that didn't matter a lot in the light of early tolerances. Other waggonways around Tyneside were anywhere between 3'6" and 5', so it's purely a historical accident, but had it been too small another gauge might well have been chosen. Other railways (and not just the GWR) did so, all regauging sooner or later. - the Eastern Counties chose 5'.

The early assumption of almost everybody bar the Stephenson set (who inherited the idea from the unfortunate William James) was that railways would be largely point to point with little need for interconnection. So Ireland ended up with a wild ragbag of gauges up to 6'2" which a government commission later "averaged" out to 5'3", which they still sadly have to use. Stephenson's track gauge turned out to be in the right ballpark. It's a pity he got the loading gauge far too small.

American railways made the same assumptions, and this only really got fixed after the Civil War.

 

[mike57]

So Ireland ended up with a wild ragbag of gauges up to 6'2" which a government commission later "averaged" out to 5'3"

And this raises the question, if instead Ireland had standardised on 4ft 81/2in would the railways there be in better shape today, as they could buy 'off the peg' rolling stock

 

[edwin_m]

So Ireland ended up with a wild ragbag of gauges up to 6'2" which a government commission later "averaged" out to 5'3", which they still sadly have to use.

And Australia ended up with three gauges instead of two (I think they employed an Irish engineer!).

Back in the 1970s the Bay Area Rapid Transit (around San Francisco) was envisaged as a new system employing optimal technology rather than being constrained by existing railway practice. Among other mistakes they went for a gauge of 5'6", only otherwise seen in India and neighbouring countries.