Why didn't Brunel settle for 7 feet?

[rockershovel]

Fascinating stuff, about the atmospheric railways.

 

Of course, the underlying concept might be regarded as little different from the linear induction motor...

Edited March 28, 2018 by rockershovel

[LMS2968]

Fascinating stuff, about the atmospheric railways.

 

Of course, the underlying concept might be regarded as little different from the linear induction motor...

...or cable haulage using stationary steam engines.

[Pacific231G]

Fascinating stuff, about the atmospheric railways.

Of course, the underlying concept might be regarded as little different from the linear induction motor...

Which also tends to be attractive to engineers but ends up only being used in small specialist applications such as at airports. The atmospheric railway did turn out to be a blind alley, at least in Victorian times, but my point is that the engineers who adopted it weren't fools for doing so.

[PatB]

Something else which needs to be remembered is that from concept to final extinction the broad gauge lasted 57 years. Rather longer than many technological dead ends and, for example, a lot longer than much of the infrastructure that resulted from the 1955 Modernisation Plan, which was formulated by people who might reasonably be expected to know what a railway should look like.

[kevinlms]

Something else which needs to be remembered is that from concept to final extinction the broad gauge lasted 57 years. Rather longer than many technological dead ends and, for example, a lot longer than much of the infrastructure that resulted from the 1955 Modernisation Plan, which was formulated by people who might reasonably be expected to know what a railway should look like.

The Broad Gauge did in fact work and did do so well. The stock was virtually identical except for the track gauge to standard gauge stock. It's major disadvantage was that freight in particular, needed to be transhipped at every location where there was a mismatch. Since the amount of BG was much less than SG, eventually it had to be chosen to abolish it rather than the other way around.

[GeoffAlan]

As an aside, various broad gauges survive around the world mostly 5' and a bit. Had Germany won the Second World War he'd a plan for a 3 metre gauge to the conquered Russian territories. Quite how the 3m gauge would have looked and performed, we'll thankfully never know. The surviving examples of broader gauges don't ever seem to be able to boast many advantages. Perhaps because most locomotive stock is based on the 4'8.5" gauge.

[Wickham Green]

The surviving examples of broader gauges don't ever seem to be able to boast many advantages. Perhaps because most locomotive stock is based on the 4'8.5" gauge.

.......... that's certainly the case in Ireland where most recent passenger stock has utilised bodyshells originally designed for the UK market ( for understandable economies of scale reasons ) .......... I can't comment on Iberia or Australia but having ridden many miles on the Indian 5'6'' can confirm that the greater width of their loading gauge is taken full advantage of. Twenty or more coaches are the norm for long distance services - and they're BIG & heavy coaches - but they have adequate space to squeeze ample motive power into a single locomotive .... there's no 4’8½’’ restrictions there !

[Edwin_m]

.......... that's certainly the case in Ireland where most recent passenger stock has utilised bodyshells originally designed for the UK market ( for understandable economies of scale reasons ) .......... I can't comment on Iberia or Australia but having ridden many miles on the Indian 5'6'' can confirm that the greater width of their loading gauge is taken full advantage of. Twenty or more coaches are the norm for long distance services - and they're BIG & heavy coaches - but they have adequate space to squeeze ample motive power into a single locomotive .... there's no 4’8½’’ restrictions there !

But I think you'll find the American loading gauge is just as big and that's on standard track gauge. 

 

Incidentally the Auckland suburban EMUs on the 3'6" gauge are also from CAF and have considerable similarities to their Irish DMUs and also to the class 332 and 333 in the UK.  So a similar design has been adapted for three track gauges. 

[John_Miles]

In that excellent  book by Miles, Thomas and Watkins (some connection) on the Swansea Vale Railway there is quite a bit about the Broad Gauge because the citizens of Swansea and its environs were up in arms about the fact that the need for transhipment except for destinations on the southern part of the GWR was hampering the trade of local industries. They were encouraging any railway company which showed any interest in promoting a standard gauge line towards Swansea to "connect them to the rest of the country". So when the Swansea Vale reached Brynamman and connected with the then Llanelly Railway via a single track line with 1 in 40 gradients there was dancing in the streets  ( slight exaggeration).  This lack of easy connectivity would have had an impact on  the wide range of industries which existed in the area such as non-ferrous metal smelting, tinplate production and anthracite mining.

[Mark Saunders]

In that excellent  book by Miles, Thomas and Watkins (some connection) on the Swansea Vale Railway there is quite a bit about the Broad Gauge because the citizens of Swansea and its environs were up in arms about the fact that the need for transhipment except for destinations on the southern part of the GWR was hampering the trade of local industries. They were encouraging any railway company which showed any interest in promoting a standard gauge line towards Swansea to "connect them to the rest of the country". So when the Swansea Vale reached Brynamman and connected with the then Llanelly Railway via a single track line with 1 in 40 gradients there was dancing in the streets  ( slight exaggeration).  This lack of easy connectivity would have had an impact on  the wide range of industries which existed in the area such as non-ferrous metal smelting, tinplate production and anthracite mining.

 

Rather like the VHS, Betamax wars!

[Pacific231G]

The Broad Gauge did in fact work and did do so well. The stock was virtually identical except for the track gauge to standard gauge stock. It's major disadvantage was that freight in particular, needed to be transhipped at every location where there was a mismatch. Since the amount of BG was much less than SG, eventually it had to be chosen to abolish it rather than the other way around.

It's other major disadvantage was that  for a small increase in loading gauge, well within what standard gauge could and in other countries does accomodate, the infrastructure costs would have been significantly higher. Minimum curves would have been larger, sleepers would have had to be longer and possibly of greater cross section to handle greater bending moments; points would have been longer for the same crossing angle so yards and other formations would have been longer and therefore requiring more land and so on. On rolling stock axles would presumably have also had to be heavier, again to withstand greater  bending moments.  Brunel was clearly interested in straight, fast main lines  but had he won the gauge wars then I suspect we'd have slightly larger trains and possibly rather faster earlier. Trains would also perhaps have been rather safer in their earlier days thanks to the increaded stability with more of the vehilcle's  weight between the rails. On the down side,  because of the extra cost, we'd probably have had far fewer secondary and branch lines (but possibly more narrow gauge public railways)   and railways would have been far more of an inter-city affair with fewer industirial branches and private sidings .  

 

 

Going back to the OP, it does seem that gauges often creep out a bit. 7ft became 7ft 0.25ins, 4ft 8ins became 4ft 8.5ins, 16mm became 16.5mm and 18mm became 18.2mm.

 

OTOH I've often wondered whether Spooner's slight narrowing of 2ft gauge to what various sources give as 1ft 11 ⁵/₈  ins, 1ft 11 ¹/₂ ins (the ffestiniog's  current gauge) or 1ft 11³/₄ (the gauge  in the  FR's 1869 Act of Parliament*)  was simply 600mm expressed in the imperial units he'd have had to use. It's supposed to have been the same as the gauge used in the quarries but I wonder how much variability they had. 

 

* Clause 54 "The gauge of the railway shall be one foot eleven inches and three quarters of an inch"

Edited March 29, 2018 by Pacific231G

[Salmotrutta]

A long time ago one of the customers in the model shop I was working in bemoaned the demise of broad gauge "as by now we could have nuclear-powered trains". Mankind dodged the bullet on that one methinks.... 

[JimC]

The stock was virtually identical except for the track gauge to standard gauge stock

My understanding is the pure broad gauge coaches were ten feet wide across the body, whereas standard gauge were 7'6 in or 8ft. 

[Mark Saunders]

One thing that's always puzzled me about Brunel's broad gauge is the use of 7ft + quarter of an inch.

 

Is there some tech reason why he didn't just settle for exactly 7 feet?

 

Look at it the other way, he chose 7' feet for the wheels and add 1/4 inch to the track gauge!

[LMS2968]

My understanding is the pure broad gauge coaches were ten feet wide across the body, whereas standard gauge were 7'6 in or 8ft.

The L&YR Liverpool Southport stock in 1904 was 10 feet wide.

[Spitfire2865]

A long time ago one of the customers in the model shop I was working in bemoaned the demise of broad gauge "as by now we could have nuclear-powered trains". Mankind dodged the bullet on that one methinks.... 

Current Nuclear tech could make that work far safer than in the past 60 years.  Plus, it would allow electric traction without considerable infrastructure to power it reliably along many miles in areas less populated such as Middle America, Australia, Russia, etc.

Only problem is the past 60 years of poor nuclear planning havent done much to its image.  

[rodent279]

Why does broad gauge lead to larger radius curves, and longer p&c work, sidings etc?

 

I think I can guess the answer, but can someone please confirm?

 

Cheers N

[Pacific231G]

Why does broad gauge lead to larger radius curves, and longer p&c work, sidings etc?

 

I think I can guess the answer, but can someone please confirm?

 

Cheers N

For turnout the switch would probably be the same length but for the same crossing/frog angle the lead between the heel of the switch and the throat of the frog has to be longer simply because it has further to go.

 

I have a copy of a 1940 military railway manual that gives an average length for cilvil turnout leads of 1.42GN where G is the gauge and N is the frog or crossing number. 

 

The same book quotes realtive volumes of earthworks as 100% for standard gauge, 75% for 3ft 6in gauge and 70% for metre gauge. Clearly that will work the other way if you increase the gauge even if the loading gauge remains the same (as it often did for 3ft 6in gauge). The figures for the total weight of track per mile, including 90lbs per yard rail, sleepers, and everything else above the ballast, are 170 tons for metre and 3ft 6in gauge, 230 tons for standard gauge and 260 tons for 5ft 6in (Indian) gauge track. Since the weight of rail is the same the main difference will, unless I'm missing something, be the weight of sleepers.

 

If curves can be smaller on NG railways than on SG then it surely follows that the minimum curvature would have to be greater for BG. Given that the centripetal forces should be the same for a given speed and weight irrespective of gauge then there must be other factors at play.

Edited March 30, 2018 by Pacific231G

[Pacific231G]

My understanding is the pure broad gauge coaches were ten feet wide across the body, whereas standard gauge were 7'6 in or 8ft. 

As long ago as 1912 the Berne Gauge used for international traffic in Europe, had a maximum width of 10ft 2ins though some railways had slightly more generous loading gauges.

Even as a standard gauge railway the Metropolitan Railway had a larger than normal (for Britain) loading gauge so that when a load of their steam hauled stock was made redundant by electrification in about 1910 they couldn't flog them to other railways in Briain. The result was that  sixteen MR coaches emigrated to France where they worked on a local (i.e light) standard gauge railway near Bordeaux until the late 1960s. To make them even more "foreigh" they were often hauled by diesel locos bought after the war from the American army (USATC) .   

[PenrithBeacon]

The L&YR Liverpool Southport stock in 1904 was 10 feet wide.

I haven't done much research into this area yet but I get the impression that Parliamentary Standing Orders for railway bills specified a minimum loading gauge. These standing orders were developed during the railway mania of the mid-1840s and they allowed a committee to examine bills for relevance before they were read in the Commons. Or at least that's my understanding!

 

The LYR's loading gauge was unusually wide, it had to build carriages of a more standard size for through services.

[LMS2968]

All true, but the point is that 10 foot wide stock could and did run on standard gauge track. It didn't the broad gauge to do it.

[jjb1970]

Something else which needs to be remembered is that from concept to final extinction the broad gauge lasted 57 years. Rather longer than many technological dead ends and, for example, a lot longer than much of the infrastructure that resulted from the 1955 Modernisation Plan, which was formulated by people who might reasonably be expected to know what a railway should look like.

The typical life cycle of systems continues to get shorter. If you consider large diesel engines, until not that long ago a basic engine platform could remain in a catalogue for 30 -40 years (unless it was a complete lemon), with constant updating to keep performance competitive. Nowadays that life cycle is down to 10 - 20 years. Typical ship life spans nowadays seem to be not much more than half what they were when I started my cadetship in 1989. And those are big lumpy mechanical things, when we get onto electronic systems its a lot shorter still. I was involved in a new power plant construction project and certain of the Siemens PLCs were becoming difficult to support within a couple of years of handover.

[Nearholmer]

231G

 

Yes, all those not quite 2ft gauges were originally 60cm.

 

There was a big movement among British engineers to adopt the metric system at the time the Festiniog was built, and it was overtly 60cm gauge initially. I’d have to check, but I think the Penrhyn was too, but measured between the centres of ovoid rails, so smaller that the Festioniog once measured inside the rails.

 

Kevin

[Edwin_m]

Why does broad gauge lead to larger radius curves, and longer p&c work, sidings etc?

 

I think I can guess the answer, but can someone please confirm?

 

Cheers N

It's really the loading gauge not the track gauge that determines the length of P&C work, because the length of a lead from one track to the next depends on the track spacing, which in turn depends on the width of the trains not of the track. 

 

As to curves, it comes down to the fundamentals of the railway wheel.  The tread of the wheel is coned (inclined) and the track gauge is a bit wider than the spacing between the flanges (which I think is where we came in with that quarter inch...).  This means the wheelset can move a bit laterally on the track, but as it does so the effective circumference at the two contact points changes, so a rotation of one wheel will take it further than a rotation of the other.  As the opposite wheels are linked by axles they must rotate the same number of times, but on a curve the outer wheel needs to travel a bit further than the inner one. 

 

On a relatively gentle curve the wheel will actually "steer" so the ratio of effective wheel circumferences is the same as the ratio of the curve radii of the two rails.  The flanges are not in contact with the rail, unlike a road vehicle it doesn't need a differential and neither wheel is slipping on its rail.  However on a tighter curve the difference in effective circumference is not enough to compensate, a flange starts rubbing against the rail and potentially one wheel is slipping. 

 

This undesirable behaviour starts when the ratio of the useable taper of the wheel to the diameter is the same as the ratio of the track gauge to the curve radius.  Unless the wheels are made thicker or with a greater coning angle (which causes other problems) this ratio is fixed, and the minimum desirable radius is a certain multiple of the track gauge.  Hence if the track gauge is larger the minimum radius must be larger in the same proportion. 

Edited March 29, 2018 by Edwin_m

[Steamport Southport]

I've not seen photos of George Stephenson, but there is at least one of Robert, when he was a guest of IKB at the launch of the Great Eastern.

 

launching the Great Eastern.jpg

 

I must say, Robert (seated,on the left) looks as sick as a parrot!

 

He was extremely ill at the time and both him and Brunel weren't long for this world. Both died about a month apart.

 

https://en.wikipedia.org/wiki/Robert_Stephenson#The_house_that_has_no_knocker

 

 

 

Jason