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If the gauge were 4'1½"


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Lets face it, if we didn't have railways and someone suggested running lorries hauling lots of semi trailers about 1000 tones worth, on two steel strips 4 ft 8 in apart which steel wheels with steel tyres with flanges projecting down about 2" to gude the wheels and a braking capability of about half a mile from 70 MPH they would probably be laughed at and possibly sectioned under the mental health act.

I was reading a biography of Aspinall the L&Y designer who worked in Ireland and greatly bemoaned the cramped space between the frames of std gauge locos, and had to resort to Joy valve gear with no eccentrics to get sufficient bearing area on his inside cyl locos.

All in all I think the Irish got it about right, while if we want to do 200+MPH maybe we should seriously consider 7ft gauge. 

If we had gone for 5ft 3" then the Midland 4F might have been a useful loco, and everything with outside cylinders probably would not have got built.

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Narrow gauge can move phenomenal loads when built properly. Take for example the coal and minerals carried particularly in South Africa and Queensland. Japan runs mini-Skinkansen on 3'6" gauge, however they are limited to 130 km/h (80 mph) due to the alignment. They have done studies that 230 km/h (140 mph) would be possible on narrow gauge with curves no tighter than 4000m radius. 

Queensland's tilt trains run at up to 160 km/h, however the narrow gauge limits the tilting to 5 degrees.

 

However balancing  would be an issue with taller vehicles. It's possible that double stacking containers wouldn't be possible on 4'1½".

 

Cheers

David

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Thailand's railways are either 3' or 1m (I never can remember). Their trains are UK loading gauge or possible a bit bigger. They even have class 158s running on a narrower chassis.

The difference is speed. Their system is very slow compared to the UK.

The only exception is the 100mph Siemens Desiros they have on their airport link (vitually similar those used in Heathrow connect), but that is a new 4'8½" railway.

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If you want an example of a railway whose stock is oversize in relation to the track gauge look no further than the Channel Tunnel. It may be standard gauge, but the proportions of the stock almost exactly match those of the 15" gauge Romney, Hythe & Dymchurch Railway, which could best be described as 1/3 scale bodies on 1/4 scale track.

 

One thing that a narrower track gauge would have affected markedly would have been first generation diesel-electric and electric locomotives, with their commutator traction motors. A 7" reduction in track gauge results in a disproportionate reduction in the length of the traction motor windings, the part that turns the electrical power into mechanical force. The effect is not so marked with the induction motors used with modern three-phase traction drives, but they are a recent invention on the timeline of railway history.

 

Jim 

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Standard gauge was used because it was already there, on industrial railways and tramways.  Where it came from before that is a bit of a mystery.  The best theory is probably that it was nominally 5 feet but measured to the outside or middle of the rails, not the inside (this would make some sense for a grooved tramway).

 

Would 4' 1 1/2" be a nominal 4' 6"?

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12 hours ago, DavidCBroad said:

All in all I think the Irish got it about right, while if we want to do 200+MPH maybe we should seriously consider 7ft gauge. 

Err, there are numerous standard gauge railways that already run at 200+ Mph!

46365447635_9aea8d452e_h.jpg

My good friend James took this picture on a Chinese train in March last year (that's around 220 Mph!).

As I'm sure you know, the French have run trains at well over 300 Mph.

I don't think we need worry about having to increase the track gauge for at least another century or so.

 

As to the OT, if "standard" gauge had been 4'1½", then model railway gauges would have been proportionately smaller and so 0 gauge would have come out around 28mm and therefore H0 (half 0!) would have been around 14mm. As usual, the smaller British loading gauge would have created problems therefore "00" gauge would have been around 12mm!!!

 

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13 hours ago, DavidCBroad said:

while if we want to do 200+MPH maybe we should seriously consider 7ft gauge. 

Not the case at all! Certain oscillations of the running gear at high speeds are difficult to control if the wheelbase is small compared to the gauge, so broad-gauge lines would have serious issues at high speeds. That's one of the reasons why Spanish and Indian high-speed rail projects are going for standard gauge. Purely from that perspective, the narrowest gauge possible makes sense, which probably goes some way to explaining enthusiasm for the concept of a high-speed monorail.

 

Other considerations, of course, prevent the gauge from getting too small - countries with narrow-gauge systems have also found standard gauge preferable for high-speed rail! Tellingly, the Shinkansen system is standard gauge, despite being a completely clean-sheet design and not having to worry about interchangeability with any other rail networks.

 

There's probably an optimum gauge for any given application, but available evidence suggests that for most applications the theoretical advantage of that optimum gauge over 4'8.5" is very small. The Russians aren't changing gauge for their high-speed rail projects, which suggests that 5' and 4'8.5" are both close enough to the optimum that it doesn't really matter which you use.

 

Of course, the designers (non-railway engineers) of the Bay Area Rapid Transit system also decided to start from a clean sheet and came up with 5'6" as the ideal gauge for their purpose. But on the other side of the coin, they also didn't discover the importance of coned wheels, so I wouldn't place too much emphasis on their findings. For the contrary viewpoint, look up Robert Fairlie's Railways or No Railways, in which the inventor of the eponymous locomotive advocates for gauges as narrow as 2'6"!

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6 minutes ago, Allegheny1600 said:

 

 

As to the OT, if "standard" gauge had been 4'1½", then model railway gauges would have been proportionately smaller and so 0 gauge would have come out around 28mm and therefore H0 (half 0!) would have been around 14mm. As usual, the smaller British loading gauge would have created problems therefore "00" gauge would have been around 12mm!!!

 

err not quite, HO would still have been 3.5mm to the foot, OO would have been 4mm to the foot with track at 14mm instead of  16.5mm for 4ft 1.5 in

Edited by TheQ
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5 minutes ago, TheQ said:

err not quite, HO would still have been 3.5mm to the foot, OO would have been 4mm to the foot with track at 14mm instead of  16.5mm for 4ft 1.5 in

Yes, of course!

Sorry about that, I think I started mixing gauge and scale ratios up somewhere, oops!:blush:

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1 hour ago, TheQ said:

err not quite, HO would still have been 3.5mm to the foot, OO would have been 4mm to the foot with track at 14mm instead of  16.5mm for 4ft 1.5 in

 

and some idiot on a forum would be asking what trains would be like if track gauge was 3'6" rather than 4'1.5".

 

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On 23/02/2020 at 08:55, TheQ said:

........ Loading gauges were often set by how well the railway was funded.  Witness the small tunnels in the south east and Isle of wight.

If the south east tunnels you're thinking about are those on the Hastings line, this was absolutely nothing to do with funding. The contractors only lined the tunnels with one ring of brickwork instead of the specified four - so the only way to rectify them was to line them down ........... OK, maybe if the railway hadn't opted for the lowest tender ( i.e. funding ), they might have ended up with reputable contractors .... but ............

 

Anyway - back to track gauges -  7' gauge may have been the broadest that was actually installed ( other than for dockside cranes and the likes ) but there was a proposal for three metre gauge high speed lines back in the thirties ....... the idea of some chap called Adolf .........................................

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1 hour ago, Wickham Green said:

Anyway - back to track gauges -  7' gauge may have been the broadest that was actually installed ( other than for dockside cranes and the likes ) but there was a proposal for three metre gauge high speed lines back in the thirties ....... the idea of some chap called Adolf .........................................

Saw something about this on a high-numbered Freeview channel a few months ago (assuming your're referring to "three-metre gauge" not three separate metre-gauge lines...).  They mentioned that engineers had said (probably not to Adolf himself) it was totally impossible, but didn't explain why.  Any suggestions?  

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On 23/02/2020 at 10:19, Trog said:

Apparently standard gauge is about at the sweet spot, for usefulness. Go much smaller and you start having to reduce the speed or the size of your rolling stock. Go much wider and you start to get problems with cornering and need greater radii for your curves. But do not get a huge advantage in stock size, as standard gauge will support stock up to what is normally useful.

 

Larger and smaller loading gauges however are the real game changers. If that nice Mr Stephenson had foreseen the utility of being able to double stack freight containers, that would have been a whole new ball game.

I guess as the gauge gets wider, for a given radius curve, the difference in length between inner and outer rail increases. This means that the difference in rotation speed between inner and outer wheels becomes greater, which I guess increases wheel and rail wear?

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1 hour ago, Edwin_m said:

Saw something about this on a high-numbered Freeview channel a few months ago (assuming your're referring to "three-metre gauge" not three separate metre-gauge lines...).  They mentioned that engineers had said (probably not to Adolf himself) it was totally impossible, but didn't explain why.  Any suggestions?  

Presumably you'd need to increase the axle diameter to maintain stiffness, which would make wheelsets very heavy, increasing the unsprung weight. To compensate, you'd need thicker, heavier rails, to avoid rail breakages.

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1 minute ago, rodent279 said:

I guess as the gauge gets wider, for a given radius curve, the difference in length between inner and outer rail increases. This means that the difference in rotation speed between inner and outer wheels becomes greater, which I guess increases wheel and rail wear?

 

I think it is more of an angle of attack problem where the axle is not at 90' to the line of the rails, leading to side wear and wheel flange wear.

 

The difference in distance travelled between the two wheels, is taken up on all but the most severe curves by the coning of the wheels.  On a curve the wheel set moves to the outside of the curve, so the outside wheel is running on its thick side, and the inner on the smaller. So for each rotation of the axle the outer wheel rolls further than the inner. The coning is usually set at an angle of 1 in 20, the rails are also inclined inwards at 1 in 20. This gives a self centring action so the wheel sets stay in the middle of the track without to much wear on the flanges.  

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But for the same radius curve the difference in running distance between the two wheels would be greater for a wider track gauge.  So to avoid flange contact, the coning angle would have to be steeper or the wheel would have to be thicker.  

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1 hour ago, Trog said:

 

I think it is more of an angle of attack problem where the axle is not at 90' to the line of the rails, leading to side wear and wheel flange wear.

 

The difference in distance travelled between the two wheels, is taken up on all but the most severe curves by the coning of the wheels.  On a curve the wheel set moves to the outside of the curve, so the outside wheel is running on its thick side, and the inner on the smaller. So for each rotation of the axle the outer wheel rolls further than the inner. The coning is usually set at an angle of 1 in 20, the rails are also inclined inwards at 1 in 20. This gives a self centring action so the wheel sets stay in the middle of the track without to much wear on the flanges.  

On a curve, the leading wheelset will move outwards as the radius tightens, until it reaches flange contact, whereas the trailing wheelset will remain largely centred. At the same time, the leading wheelset will be at a progressively increasing angle of attack to the outer rail, leading to significant longitudinal and lateral (gauge spreading) forces at the rail head. Because the contact patch is at an angle to the rail, the wear mechanism becomes predominantly scrubbing. The free-curving radius, ie the minimum before flange contact occurs, is relatively large for normal railway wheel, and whilst I no longer have the figures to hand, can be reckoned to be in four figures in metric terms. Wheel profiles can be designed so as to give much higher than normal conicities (the measure of how small a curve radius they can cope with before getting into flange contact), but there is a trade off against the maximum speed at which they will run without instability (hunting) setting in.

 

Jim

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11 hours ago, Allegheny1600 said:

Err, there are numerous standard gauge railways that already run at 200+ Mph!

 

My good friend James took this picture on a Chinese train in March last year (that's around 220 Mph!).

 

 

 

A bit of trivia, the chase plane is an Aérospatiale Corvette F-GPLA. It is fitted out for aerial photography and has been hired by Airbus on numerous occasions as a chase plane during flight testing. I doubt there are many civilian pilots that get to fly at this sort of speed at such a low altitude on a regular basis.

Edited by DavidB-AU
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Indian Railways meter gauge trains appear to be the same loading gauge as their broad gauge cousins, but during my visit there in 1987 ran at a lower speed than broad gauge. I understand most o the meter gauge network has been converted to broad gauge, apart from "hill" railways such as the famous Nilgri Hills line.

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Is there any reason (other than increased complexity and costs) why full sized railways can't adopt independently rotating wheelsets, as used in some ride-on applications, to allow use of small radii without excessive scrubbing? 

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Independently rotating wheelsets are used on some light rail vehicles such as the Siemens Avenio. Even then Siemens says it's a compromise for very tight curves (like street tramways) where there is a lack of space for an axle. There are advantages such as reduced wheel wear compared with axles on the same radius, but disadvantages such as increased maintenance and ride comfort (acceptable but not as good as it could be).

 

Cheers

David

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On 22/02/2020 at 23:27, The Johnster said:

Probably fair to say that loading gauge has had far more of a restrictive effect on UK railways than track gauge.  The Japanese have 125mph services on their 3’6” network. 


I stand to be corrected but I was under the assumption that all of Japan’s high speed lines were built to standard gauge?

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36 minutes ago, jools1959 said:


I stand to be corrected but I was under the assumption that all of Japan’s high speed lines were built to standard gauge?

 

They are. To the best of my knowledge the fastest trains on 3'6" in Japan are 130 km/h (80 mph). There was a proposal for "Super Tokkyū" 3'6" gauge lines, basically Shinkansen standard in everything but gauge with a maximum speed of 230 km/h, but it never went anywhere. 

 

EDIT: I should add the Queensland Rail tilt train reached 210 km/h (130 mph) in testing but is limited to 160 km/h in regular service.

 

Cheers

David

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6 hours ago, PatB said:

Is there any reason (other than increased complexity and costs) why full sized railways can't adopt independently rotating wheelsets, as used in some ride-on applications, to allow use of small radii without excessive scrubbing? 

The "steering" effect described above, where the conicity of the wheel avoids flange contact except on tighter curves, relies on the wheels on each side rotating at the same speed.  If that doesn't happen then there is a risk the bogie starts "crabbing", or running along at an angle with the flanges on diagonally opposite wheels in contact with the rail even on straight track.  There are ways round this but they introduce more complication, for example Talgo trains have a linkage from the body sections to the two-wheeled "bogies" which keeps the axis of the wheels midway between that of the two body sections above, and therefore parallel to the track.  

 

However a system is now being tested that has independent wheels with a motor in each wheel hub and some sort of active steering of the "axle" (which connects the wheels but doesn't rotate).  Details are commercially sensitive but it appears to be measuring the curvature and using this to steer the axle to the correct angle and also to adjust the relative rotation of the two wheels so flange contact is avoided even on tight curves.  

Edited by Edwin_m
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13 hours ago, Trog said:

 

............ The coning is usually set at an angle of 1 in 20, the rails are also inclined inwards at 1 in 20. This gives a self centring action so the wheel sets stay in the middle of the track without to much wear on the flanges.  

Yes, it's usually 1 in 20 in the UK - but most of the world uses 1 in 40, i believe ...................... so you'd need even wider tyres for the coning to be effective on three-metre gauge .... and lots of gauge widening !

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