Standard gauge
Discussion
thewarlock said:
100SRV said:
Why did the standard railway gauge end up at 4' 8 1/2" - why not make it a round 5' ?
IIRC, George Stephenson measured the track width of loads of farm wagons, and took the average, the idea being people would be allowed to use the railway themselves.No idea if that's true but sounds plausible and it's a nice story.
The choice of a gauge somewhere between 4 and 5 foot is just the result of that being the approximate width of a pony or horse. If you need to fit the beast between the rails (or the shafts of the wagon/cart sized to run on the rails) you're going to end up with the rails being that sort of distance apart.
There's that chain email/facebook post that goes around which concludes that the width of the Space Shuttle's rocket boosters was - via the origins of the railway standard gauge - determined by the width of a Roman horse's backside, but that's a) not historically true and b) not that remarkable given that every society that independently invented horse-drawn tramways settled on a similar gauge. And the Shuttle's boosters were more restricted by the loading gauge, not the rail gauge, and one does not strictly depend on the other.
The colliery tramways of the north of England were no different, and had rails 4-foot-something apart. The exact distance depended on the personal choice of the engineer, the size of the animals (were they small pit ponies dragging the wagons out from underground or where they larger draught horses hauling wagons from the pit to a canal wharf or furnace) and the size of mine workings which depended on the geology and mineral type.
George Stephenson favoured 4ft 8in, a size already in use in the collieries of Northumberland and Durham. The region already had hundreds of standardised wagons (chaldrons) in use and the Stockton & Darlington railway was built to carry these and so used the same gauge. The extra half inch was added in the 1830s during the development of mainline railways since it allowed for imprecision in construction and differential wear of the wheelsets - if everything was built to a nominal 4ft 8in, then it only takes a wheelset to be slightly too wide for very strong drag or binding forces - enough even for the wheels to 'pop' and derail - to develop on corners. So the wheelsets were all made to a 4ft 8in standard and the rails were laid to 4ft 8.5in so the tolerances achievable at the time all averaged out. Very quickly it became possible to both build wheelsets and lay rails (plus things like the development of improved rail profiles) with better accuracy and 4ft 8.5in became the true standard.
There's that chain email/facebook post that goes around which concludes that the width of the Space Shuttle's rocket boosters was - via the origins of the railway standard gauge - determined by the width of a Roman horse's backside, but that's a) not historically true and b) not that remarkable given that every society that independently invented horse-drawn tramways settled on a similar gauge. And the Shuttle's boosters were more restricted by the loading gauge, not the rail gauge, and one does not strictly depend on the other.
The colliery tramways of the north of England were no different, and had rails 4-foot-something apart. The exact distance depended on the personal choice of the engineer, the size of the animals (were they small pit ponies dragging the wagons out from underground or where they larger draught horses hauling wagons from the pit to a canal wharf or furnace) and the size of mine workings which depended on the geology and mineral type.
George Stephenson favoured 4ft 8in, a size already in use in the collieries of Northumberland and Durham. The region already had hundreds of standardised wagons (chaldrons) in use and the Stockton & Darlington railway was built to carry these and so used the same gauge. The extra half inch was added in the 1830s during the development of mainline railways since it allowed for imprecision in construction and differential wear of the wheelsets - if everything was built to a nominal 4ft 8in, then it only takes a wheelset to be slightly too wide for very strong drag or binding forces - enough even for the wheels to 'pop' and derail - to develop on corners. So the wheelsets were all made to a 4ft 8in standard and the rails were laid to 4ft 8.5in so the tolerances achievable at the time all averaged out. Very quickly it became possible to both build wheelsets and lay rails (plus things like the development of improved rail profiles) with better accuracy and 4ft 8.5in became the true standard.
Simpo Two said:
Brunel's broad gauge made a lot of sense IMHO. It seems odd to have railway carriages on such relatively narrow track. Guess it saves money on sleepers!
Brunel's 7ft 1/4in gauge was - like a lot of his ideas - based on his particular intellectual habit of looking so far forward that he couldn't see what was right under his feet, as it were. The Stephenson standard gauge does not really impose great limitations on either speed (the fastest trains in the world run on standard gauge) or loading gauge (witness some of the huge rail vehicles running on standard gauge in the USA, Australia and Russia). In neither case are the engineering limits caused by the rail gauge. In the 1830s Brunel's choice of 7ft 1/4in gauge made intuitive sense. It seems obvious that a wider gauge allows bigger, more powerful, faster and more stable locomotives hauling wider, more capacious, more stable and more comfortable rolling stock. But this proved to not be the case. Brunel was a man of great vision and loved to re-invent new systems on a new scale (the Bristol Floating Harbour, the Great Western Railway, the SSs Great Western/Britain/Eastern, the South Devon Atmospheric Railway, the Saltash Bridge, the prefabricated field hospital and so on). But he rarely cared for making incremental improvements to the existing state of the art. So in the case of the GWR he failed to realise (or foresee) that it wasn't standard gauge as such that was holding rail travel back from meeting his vision. Improvements in locomotives, rolling stock, track design and permanent way could all go together to achieve his aims without needing to adopt a unique (and absurdly wide) broad gauge and a new form of track construction (timber baulk road). Brunel also, for some reason, insisted on highly conservative engineering specifications for the GWR's original stud of locomotives, which completely failed to make use of the potential of the broad gauge in either power or speed - they were significantly inferior to the norm for standard gauge engines of the era. And don't overlook that Brunel's intended vision for broad gauge rolling stock was for the coach bodies to be slung between the wheels, which would be large stagecoach style affairs, providing a better ride and stability. But how were you going to board a carriage with the wheels up the side, the paddleboxes of a paddle steamer? Brunel never answered this question and the GWR adopted conventional carriages.
There's no evidence from the GWR's broad gauge era that it was technically, dynamically, economically or functionally superior to the standard gauge competitors. For all it's magnificent appearance, a Western 'Rover' class was no faster, no more efficient and no more capable than a GNR Single or an LNWR 'Bloomer'. The continual cramping factor on British railways has always been our restrictive loading gauge, not the track gauge. The broad gauge legacy gave the GWR a slight advantage in that regard but if Brunel had been a true visionary he would have adopted standard track gauge and a 3.3m x 4.8m loading gauge.
It's this sort of 'wood for the trees' thinking that makes Brunel fascinating. Take the Great Eastern for instance; the problem was that there was no coal available for ships to refuel between Europe and Australia. Brunel's solution was to design a ship five times the size of any yet built in human history so it could carry all its fuel on a complete road trip. Other engineers - with less vision but more pragmatism - set up a network of coaling stations allowing ordinary ships to make the journey in stages. Less efficient, less pleasing to the engineering mind, but much more practical. The atmospheric railway embodied exactly the same thinking that makes electric traction the optimal choice for modern rail transport - removing the power source from the train itself, centralising the power generation in fixed, remote sites where it can be generated at large scale and peak efficiency and then distributing it to the trains as required - but Brunel failed to notice both the huge steps forward made in locomotive engineering between the atmospheric principle being first demonstrated and the choice to use it for the South Devon, and that the material technology of the mid-Victorian period simply wasn't up to permitting the atmospheric system to work at the scale he envisioned.
Old horse and cart type wagons had evolved into a standardised axle width because before roads were paved it was convenient for one wagon to follow in the tracks of another rather than bumping over fresh ground. This simply carried forward to the railways, early "coaches" being exactly that - horse drawn coaches adapted to run on rails.
One reason three wheeler cars are a PITA is because the "odd" wheel has to travel over parts of the road where nobody else drives. Steer the front round a pothole or manhole cover and the back just crashes through it.
One reason three wheeler cars are a PITA is because the "odd" wheel has to travel over parts of the road where nobody else drives. Steer the front round a pothole or manhole cover and the back just crashes through it.
I don't know if it was the South Devon railway, or another atmospheric one (was there another?) but I remember 20+ years ago Adam Hart David was doing his Local Heroes series and did a feature on it. I think he used a Henry hoover and some drain pipe, but as a kid I thought it was fascinating. Although I could see the problem with leaky leather flaps even as a kid. Imagine if BR had got hold of an atmospheric railway, there'd be small children and dogs getting sucked up the tubes!
I was a kid/teenager when the email chain about the Space Shuttle boosters being sized by a pair of roman equine asses and it was one of my favourites and I used to recite it regularly, that and the 'Americans spent millions making pens that worked in space, Russions just took pencils!'. Both a load of boll@ks when you actually think about it.
Interesting about the added 1/2 inch to allow for tolerance of manufacturing. Like the OP I always though it was a stangely specific sizing for something that was just made up in the first place, but it makes sense now.
I was a kid/teenager when the email chain about the Space Shuttle boosters being sized by a pair of roman equine asses and it was one of my favourites and I used to recite it regularly, that and the 'Americans spent millions making pens that worked in space, Russions just took pencils!'. Both a load of boll@ks when you actually think about it.
Interesting about the added 1/2 inch to allow for tolerance of manufacturing. Like the OP I always though it was a stangely specific sizing for something that was just made up in the first place, but it makes sense now.
Just to add, some of the early lines didn’t believe that this newfangled steam traction would ever take off, and planned their lines to be horse drawn.
The line between Newcastle and Carlisle is an early one, and still has some of the stream fed horse troughs set into the retaining walls.
The line between Newcastle and Carlisle is an early one, and still has some of the stream fed horse troughs set into the retaining walls.
Simpo Two said:
Brunel's broad gauge made a lot of sense IMHO. It seems odd to have railway carriages on such relatively narrow track. Guess it saves money on sleepers!
Queensland uses Narrow gauge (yes, really) on almost all of the railways because it was cheaper to build.The only Standard gauge line is the one that connects to NSW because they use Standard gauge.
100SRV said:
Why did the standard railway gauge end up at 4' 8 1/2" - why not make it a round 5' ?
According to my history teacher it was the length of Stevenson's arm span. He was asked how wide to space the tracks and stood arms outstretched and said "this far". Not sure how much truth is in that but it is a nice anecdote and despite having little interest in railways it is a measurement I have remembered for the last 30+ years.
LimaDelta said:
100SRV said:
Why did the standard railway gauge end up at 4' 8 1/2" - why not make it a round 5' ?
According to my history teacher it was the length of Stevenson's arm span. He was asked how wide to space the tracks and stood arms outstretched and said "this far". Not sure how much truth is in that but it is a nice anecdote and despite having little interest in railways it is a measurement I have remembered for the last 30+ years.
Simpo Two said:
LimaDelta said:
100SRV said:
Why did the standard railway gauge end up at 4' 8 1/2" - why not make it a round 5' ?
According to my history teacher it was the length of Stevenson's arm span. He was asked how wide to space the tracks and stood arms outstretched and said "this far". Not sure how much truth is in that but it is a nice anecdote and despite having little interest in railways it is a measurement I have remembered for the last 30+ years.
It may be linked to a measurement over the rails which may be 5ft.
Gauge is a compromise.
Wide gauge (e.g. Brunel’s) made more powerful steam engines easier to achieve and is more stable at sped but the train doesn’t go round corners very well.
Narrow gauges (e.g. 2ft 6in) allows easier cornering, even if at lower speeds, but are terrible for high speed stability.
Any size of train could run on any gauge of track but they might look a bit stupid.
There are still countries with more than one gauge.
Gauge is a compromise.
Wide gauge (e.g. Brunel’s) made more powerful steam engines easier to achieve and is more stable at sped but the train doesn’t go round corners very well.
Narrow gauges (e.g. 2ft 6in) allows easier cornering, even if at lower speeds, but are terrible for high speed stability.
Any size of train could run on any gauge of track but they might look a bit stupid.
There are still countries with more than one gauge.
gazzarose said:
I don't know if it was the South Devon railway, or another atmospheric one (was there another?) but I remember 20+ years ago Adam Hart David was doing his Local Heroes series and did a feature on it. I think he used a Henry hoover and some drain pipe, but as a kid I thought it was fascinating. Although I could see the problem with leaky leather flaps even as a kid. Imagine if BR had got hold of an atmospheric railway, there'd be small children and dogs getting sucked up the tubes!
I don't know about the TV feature, but there was another atmospheric railway - the London & Croydon Railway, which ran an atmospheric system between Forest Hill and West Croydon in the 1840's. It was beset by issues with the steam engines which generated the vacuum, and a planned extension of atmospheric locomotion onwards towards Epsom and from Forest Hill back towards London Bridge was never completed.Kim
2xChevrons said:
Brunel was a man of great vision and loved to re-invent new systems on a new scale (the Bristol Floating Harbour…
Tiny point of detail but ‘The Float’ is not actually Brunel’s work. IIRC William Jessop is your man. Later on Brunel designed some better lock gates and stuff to stop The Float silting up. Yertis said:
Tiny point of detail but ‘The Float’ is not actually Brunel’s work. IIRC William Jessop is your man. Later on Brunel designed some better lock gates and stuff to stop The Float silting up.
Thanks for picking that up. It was the entry in that list that tinkled a warning bell in my mind when I wrote it, but I knew he'd had something to do with the Bristol docks. It's been 15+ years since I had to be able to rattle off Brunelian projects off the top of my head - getting rusty!Simpo Two said:
Thinking of the atmospheric railway and its remote power source, do you think that if Brunel had been 30 years later he would have done something remarkable with electric power? Brunel + Armstrong, now there's a team.
Brunel would have been all over electric railways and electrification in general had he been around at the right time. As I mentioned up-thread, his attraction to the atmospheric railway was based on the same principles as electrification - generating the power remotely allows for much more power and much greater efficiency than each train having its own power units - but the atmospheric system didn't deliver those benefits in practice and the material technology of the time wasn't up to the job (amongst other failings of the scheme). Brunel was predominantly a civil engineer (in the modern sense) and liked to think in terms of 'systems' - he envisioned, planned and constructed on a big scale. He wasn't averse to detail work, be it an individual structure like the Maidenhead Viaduct or Saltash Bridge, or right down to him doing the architecture for all the GWR's original stations or even personally designing the mileposts and trackside signage. But they were always part of a greater system - the GWR wasn't just a string of bridges, cuttings, banks, stations and depots, but a holistic transport machine to connect London and Bristol. The SS Great Western was intended to extend that machine's reach across the Atlantic to New York. The Great Eastern was to do the same for Australia - I always think it's very appropriate that, after Brunel's death, the Great Eastern found her true calling as a trans-oceanic cable laying ship, because that's something that was right up Brunel's street. His 'systems' approach had blind spots, to be sure - had he carried his approach through to its logical conclusion then he'd have realised that adopting a non-standard rail gauge just made the railway system, and his railways' part in that system, less effective. But the only thing bigger than Brunel's ships was Brunel's ego.
With all that said, I can absolutely see him being in the vanguard of electrification - it makes for the most effective and efficient rail transport system. Brunel excelled in many areas but mechanical engineering was not one of them. All the steam locomotives he designed or specified were, to be frank, utter crap and the steam plant for his ships were unambitious and old-fashioned, mostly relying on 'being very big', which introduced all sorts of manufacturing issues. You can easily predict a slightly-out-of-time Brunel consulting with Armstrong, Crompton, Parsons and Ferranti and then coming up with some hugely advanced high-voltage multi-phase AC supply standard which was just beyond the cutting edge of Victorian electrical engineering while IKB penned designs for ram-nosed mahongany-panelled electric rail carriages which would zip to Penzance at 180mph, drawing power from Arts and Crafts-styled power stations with floors covered in allegorical mosaics and stained glass windows.
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