Elvas Tower: Traveling too slow for this curve - Elvas Tower

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Traveling too slow for this curve

#1 User is offline   Genma Saotome 

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Posted 05 September 2018 - 08:51 PM

4mph thru the diverging path of a switch....

What is that message about? What parameter values/settings are necessary to make it go away?

#2 User is offline   steamer_ctn 

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Posted 06 September 2018 - 12:00 AM

View PostGenma Saotome, on 05 September 2018 - 08:51 PM, said:

4mph thru the diverging path of a switch....

What is that message about? What parameter values/settings are necessary to make it go away?


Have a look at this thread, and the referenced article for a description of the feature in real life.

As you suggest, perhaps a yard would not have superelevated track, and therefore cars toppling over would not be an issue. Therefore ideally there should be no error messages when traversing small switches or curves in yards.

I can think of two possible ways to solve the problem:
i) Set a minimum curve radius before the alarm indicates. So what would be the maximum curve radius used in a yard, but not on a main line? Would 100m be a safe bet?
ii) Disable the alarm indication on switches. This would solve the problem perhaps for yard switches, but I am not sure how to identify whether a car is on a switch or not.

I suspect that i) is the easiest solution, but happy to consider ii) if somebody can suggest how to identify when a switch is under a wagon.

Thanks

#3 User is offline   Goku 

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Posted 06 September 2018 - 06:20 AM

In real life there are no superelevated curves when too slow speed is dangerous. It would be insanely stupid. There are many situations where train can't keep optimal speed and must drastically slow down or even stop.

I don't see a reason for this message.
Also that's why I don't like OR superelevation, because it works for every track, but in real life that's not the case.

Here I've recorded emergency stop at steep curve adjusted to 160 km/h. Nothing happened:
https://youtu.be/PW8AG3Jf67g?t=3189

#4 User is offline   Genma Saotome 

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Posted 06 September 2018 - 08:43 AM

I agree w/ Goku, tho I'm no expert on the subject so perhaps there are reasons that argue for the feature.

If it is to remain as a feature then I recommend de-coupling it from whatever assumed cant is used for the display of track (we use only one value for software purposes due to the limits of the 3dmodels for track) and instead tying the calculation to an assumed cant based either on the current speed limit alone (which should be based on the tightest curve) or some ratio of speed limit and current curvature (I expect that ratio would need to be a curve). Surely there are formulas that can be found in the engineering literature that present typical cant amounts for various speeds.

I suspect there are also speed limits set so low as to fall under a practical limit of don't bother... for example, if for whatever reason the speed limit in a switching yard is, say, just 10 mph it's pretty safe to either assume no curve has a cant built into it or that the chance of tipping over on whatever slight cant might be present is actually nill. I do not know what value to suggest for such a limit.

If the track doesn't have an assigned speed limit assume it has no cant (e.g., perhaps it's a route under development).

#5 User is offline   Mike B 

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Posted 06 September 2018 - 08:55 AM

I think this video shows what the message is aimed at - stringline derailment: https://www.youtube....h?v=CgqdIjp6zuQ

That can happen even without much (or any) super if the curve is tight enough and the train improperly built or handled. But as currently implemented it's not very sensitive to conditions; as noted, low speeds are normal (and required!) in a yard, and even if super is applied to the diverging line of a switch (which OR does) it's not going to matter much over the short distance involved. The two alternatives above are good to think about; another possibility might be to make OR aware of "yard limits" and not apply super (or trigger super-related messages) within them.

#6 User is offline   steamer_ctn 

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Posted 07 September 2018 - 04:33 PM

Whilst I agree that the best way to adjust the slow speed message might be to use the "Yard" definition from MSTS (though not all routes probably have yards defined in them) I am unaware as to whether OR reads the yard definition, and how to access it in the code.

I have now put a limit in to prevent the message appearing on curves of less then 150m radius. Hopefully this should cover all yard type scenarios.

#7 User is offline   ebnertra000 

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Posted 07 September 2018 - 06:58 PM

A 150m radius is probably too tight in most cases, as many yards use 10d switches (164m), or maybe 7.5d (190m). Do you think it would be possible to select a track piece and insert some kind of flag, probably in the .w file, that says to the code 'Do not superelevate this track'? It would be useful not only in switches and yard tracks, but also on industrial spurs and other low-speed trackage

#8 User is offline   Genma Saotome 

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Posted 07 September 2018 - 08:35 PM

Peter, the error pops when super-elevation display is not activated. It also occurs in all slow speed limit situations where little to no cant would be present w/o regard to curvature (I have seen 2000m curves in a yard and in one of my routes I have 10 congruent 340r curves). And of course when a long train is in transition from slower to faster it's speed is governed by where the end of the train is, not the front. For example any radius curve that occurs on the main while the end of the train has yet to clear the slow speed switch of the siding.

IMO we should not be seeing the message in any of those situations.

Does the block of code you are working on have access to the speed limit that is presently governing the whole train?

#9 User is offline   steamer_ctn 

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Posted 08 September 2018 - 01:32 PM

Given the fact that it is very difficult to definitively isolate the conditions under which the low speed indication works, I will disable the code until a better way to determine yard conditions, etc are identified.

#10 User is offline   Hamza97 

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Posted 08 September 2018 - 07:58 PM

Actually I got this message in an opposite situation. I was just driving around in Free Roam mode when I took a diverging switch at 50kmph instead of permitted 20km/h. Even then I got this message of traveling to slow for this curve.... Pretty Ironic... :rotfl:

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