Oh, yeah, Zoe, we forgot…
[dons vest worn by Nelson on “The Simpsons”:]
HAR-HAR!!
Of course, I understand the economics of it. But you see - that is why I asked the question - to see if anyone has gone against this logic 
And thank you for correcting my “guage” misspellling. As someone with a strong interest in railroading, I should know better.
The classic scenario people conjure up when they worry about trains tipping over because the gauge is too narrow is of a train being pulled by outward forces to the outside of a curve it is negotiating too fast.
To consider the real risks involved in this, consider a standard child’s HO/OO gauge oval layout on the living room table. The scale speeds of those trains are phenomenal! Yet, they whizz around those 180 degree corners in three or four seconds without tipping over. Think about this for a moment. Imagine a real train doing the same thing. It would scare the living bejeezers out of a real, human train crew. Sure, trying to do a U-turn in under five seconds probably would tip a real train, but that is because there are differences in the scale of the track (model trains run on relatively more chunky, robust track than the real life prototype). So, a full sized train may not be able to negotiate curves at quite the rate that the models do, but they can certainly do so much faster than standard rail operation allows.
The main consideration (assuming a well-surveyed and well-built right of way) is passenger comfort, not tipping concerns. The speed at which passengers will start to get anxious about tipping over on a curve is much, much lower than the actual speed at which the train will tip. This is why trains keep to the curve speeds they currently do.
This point is illustrated by the fact that “tilt trains” have been developed. These are passenger trains the bodies of which lean into curves, but the bogies, wheels, and undercarriage do not. They were designed to allow higher speeds without completely renewing the lines with banked curves (at great expense). The actual tilting doesn’t do very much at all to increase safety (the speed is still within safe margins), but it makes the passengers more comfortable. Tilt trains wouldn’t be permitted to travel at the faster speeds they currently enjoy compared to regular trains if it wasn’t safe to do so.
In a nutshell, as a passenger, you’d have a hair-raising experience of being pushed into the wall of the carriage, drinks going flying etc LONG BEFORE the train is in actual danger of tipping.
Ahahaha LOL ^^^
I was going to mention that whole HO scale analogy! I didn’t think the analogy was accurate enough though, so I didn’t bother posting. I have a setup right here in my basement, and my trains fly around those tracks and they certainly never tip over.
[nitpick]
The subways and local train lines throughout Japan are, for the most part, built, run and maintained by private companies. Japan Rail, which runs most of the intercity trains (including the bullet trains) was initially government run, but was split up into several private companies in the early 90’s (and have been profitable since then).
[/nitpick]
I was going to write about gauge affecting costs the other direction, that is to say downward. There are a number of factors that work towards having the smallest gauge practicable. Yard acreage needed, fixed costs, initial outlay, and cost of rail maintenance due to increased loading of rail among them.
But as to the OP tipping isn’t much of a problem, at least it is very rare in the real world. As The LoadedDog very nicely pointed out for passenger trains it’s a different concern that keeps the line’s designers up at night.
The only picture I ever saw of tipping in the total absence of derailment was an SP drag going upgrade when a brake failure (in this case incorrect application of brakes) in the rear of the train caused the load though the train to skyrocket.
The grade, as they often do, was snaking through pretty sharp curves and eight, or so, cars did the model railroad trick of flopping to the inside of the curve. I wish I had that picture.
Tipping over to the outside of curves can happen, but excess lateral loads usually cause derailment first. The tranverse load being applied at the railhead makes the rail act as a lever and pulls the spikes on the inside of the rail up and out. The rail rolls over and the train is then on the ground, with typically bad results.
One of the worst accidents of this ilk occured late Eighties coming down from Cajon pass in California with a 60-ish car train being braked by 6 locomotives. Turns out the load had gotten wet at some point and was 50% overweight. This, combined with two of the locomotives having inoperable dynamics brakes, had nasty consequences. The grade there is over 2% which is a pretty steep hill for trains. They don’t know how fast the train was moving because the train recording gear lonly goes up to 90 mph. Probably going 100 to 110 when it hit the first sharp turn. The lead locos basically bulldozed their way through the outside rail and into some adjacent housing.
I don’t think any practical gauge railway survives that sort of thing.
That should read:
I don’t think any gauge in use on a railway would survive that sort of thing.
I don’t suppose any of you rail geeks know some good sites that discuss the various speed and gradient regulations?
I know on one trip I take frequently there’s a portion in which the train (Via Rail as it were) slows to a crawl. I’d love to find out what kind or grade its traversing. Is it possible to get rail maps that show the grades and speed limits?
What’s the terrain like where you’re seeing this? Grades and tight curves often go together, as I’m sure you’ve noticed. If it’s hilly country, then the curves are probably the limiting factor where you’re concerned.
The train I take regularly (The Coaster) to San Diego traverses the Sorrento Valley grade at about the same speed going up and down. Passenger trains have a much better power to weight ratio than freights so the constraining factor is curve radius regardless of grade direction.
If you keep your eye peeled out the window when you travel you can see the speed limits posted by the tracks. They’ll be two numbers, one above the other, on a yellow sign about 6 by 12 inches. Top (greater) number is mph limit for passenger service; bottom (lesser) number is mph limit for freight service. My guess is that Canada uses mph for train speeds, but I might be mistaken.
More geekery:
On heavily used track there is often a little banking built into curves. It’s not very steep, usually, but it’s there if you look for it.
I ran across this account of a narrow gauge locomotive that seemed to be operating close to its ability to remain upright:
http://www.railwayeng.com/hon3/c-18sped.txt
As mentioned above, notice that it was the crew’s discomfort that finally led to a reduction in speed and an apparent return to stability. I think that most locomotives would give similar warning signs before their stability limits were surpassed. Most of the derailments mentioned above all share the characteristic of resulting from some sort of loss of control.
Yep, I’ve seen those signs before. And I think you mean kph, not mph. I’ve seen signs that have “90” on them but only once has the train ever felt like it was going anywhere near that fast.
I asked a Canadian railfan about the kph/mph question. Turns out that Canada uses mph on its speed limit signs for railroads. The locomotive manufacturers don’t have to install different speedometers and the crews (who occasionally cross the border both ways) don’t have to deal with two sets of units.
90 mph, by the way, is a common passenger speed limit on well-maintained tangent track.
I don’t know if this is the intent, but if you use millimeters you don’t have to decide which decimal marker to use (period or comma) for an international audience. Although I think you could safely use a period in English text.