Another idea for realistic engine motion

[lvf]

Dear Friends,

Recently I was reading a discussion on the motion of trains due to harmonic and rocking. The discussion brought out that to duplicate this type of motion too much processing power would be needed.

Why not have it introduced into the track shape file itself? Create different Classes of track as in the real world. MSTS already jerks the train at rough transitions in track laying, it seems that there is all ready a possibility that is built in to MSTS.

A route builder could choose the Class of track for every area or siding as needed.

If this is possible, no extra processing power would be needed and the motion would be driven by the track just as it is in the real world prototype.

Yours truly,
Leland

[longiron]

leland,
Excellent idea for going forward. It's one that already in the design spec for new routes built with new OR tools. The challenge is how to create a realistic illusion without requiring route builders to revist existing MSTS routes.

[OTTODAD]

While only one type of track can be used in a MSTS route, although there are some limited work-arounds, I can not see how certain unevenness can be added to some tracks and not others, the same track being used for high-speed mainlines, local and freight trains tracks and in yards and sidings.

TS 2012 has it now but can only be applied to all of one type of track.

O t t o

[kox]

For msts routes i think a moderate default unevenness should be set. If someone wants more, then convert it to orts format and modify it.

[mestevet]

It IS possible to simulate some level of "jerkiness" in track in MSTS, as-is. I've done it. Simply, you use short sections of track (10 - 20m) and just alter the "elevation" so that each section reverses the elevation of the last. It doesn't have to be extreme. What I'm describing clearly has to be built into the trackwork of a route though. I've done this in some locations where there are switches as well, so that the trains appear to "bounce" slightly as they pass over the switch-work.

Now that doesn't simulate "yaw" or "roll" type oscillations, which I think is part of the suggestion.

I think that one of the difficulties in doing this is to get realistic numbers on the stiffness and dampening in the suspension of various pieces of rolling stock - get the numbers wrong and a car could sway and shimmy down the track very unrealistically, or perhaps be used on a new route and find that the "fundamental frequency" of the track on that route causes a particular piece of rolling stock to behave like a baby carriage.

I will say though, that it would be cool to have something like what I saw on the NEC today, an AEM-7 at speed (over 110mph) going straight through an interlocking, but having the various components of the switch set the unit yawing back and forth for a few hundred yards down the track.

Steve

[charlie]

Recently I was reading a discussion on the motion of trains due to harmonic and rocking. The discussion brought out that to duplicate this type of motion too much processing power would be needed.

Hi Leland,

In the meantime whilst waiting around, you might try this. Works in MSTS and OR.
http://www.elvastower.com/forums/ind...azzas-k27-454/

Motion best viewed from a head-out cab view. All of this builder's steam locomotive models are so equipped (BazzaMotion). Tenders too...

EDIT: Or just watch the rocking and swaying in Shape Viewer. The motion is not "over-done".

regards,
charlie

[OTTODAD]

Motion best viewed from a head-out cab view. All of this builder's steam locomotive models are so equipped (BazzaMotion). Tenders too...

Yes, that's one alternative, but means that this loco will rock like that no matter what the quality of the track is it is running on ?

O t t o

[lindsayts]

A number of points........

The first is the subject of "cab sway" is some thing of a religous argument, ie there is a good bit of polarisation and a good portion of either side is not realy listening to the other sides point of view.

Second some tracks (not many but defintely some) do NOT produce any lateral movement in the rail vehicle. An example would be the Victorian (Australia) class 1 track from St Albans, Melbourne to Ballarat. This realy is dead smooth with the VLocity DMU's in some places doing 160KPH, all one sees is the scenery going by and feels is the 19 litre engine under the floor. Even the switching does not produce any noise or bounce.

Third point is the carriage motion is felt rather than seen. Look at how much trouble for instance the air line aircraft simulators go to to get the "feel" of the aircraft correct. Modern airlines do not spend this sort of money for nothing. Visual artifacts are always going to be something of a short cut.

Lastly from my point of view there is nothing worse in a sim than to be able to pick that something is not correct, destroys the illusion completely. The human mind is very good at picking up irregularities in things like this. A real good example for me is the stars in OR at night. Stars are points of light, the current implentation (in V6.2) of elongated nebular is totally off putting, so I sadly do not do any testing in the sim in the virtual night.

There is nothing wrong with putting in some kind of "psuedo" movement as long is it can be disabled for those that do NOT wish it to be present. Keep in mind the first point here!!!!

Lindsay

[OTTODAD]

There is nothing wrong with putting in some kind of "pseudo" movement as long is it can be disabled for those that do NOT wish it to be present.

That's the way to do it to please all !

That is what I am pushing for in TS 2012, to let users decide in it's OPTIONS what they want to disable, like Cab Sway, Shadows on tracks and all derailments, no matter what the cause is, like derailments in MSTS which lets me drive my Santa-Fe Explorer at 1500+ MpH along tracks when testing them !

O t t o

[GoGoran]

The first is the subject of "cab sway" is some thing of a religous argument, ie there is a good bit of polarisation and a good portion of either side is not realy listening to the other sides point of view.

Second some tracks (not many but defintely some) do NOT produce any lateral movement in the rail vehicle. An example would be the Victorian (Australia) class 1 track from St Albans, Melbourne to Ballarat. This realy is dead smooth with the VLocity DMU's in some places doing 160KPH, all one sees is the scenery going by and feels is the 19 litre engine under the floor. Even the switching does not produce any noise or bounce.

Sic!

And the same holds true for most European, especially German, French, Swedish and other North-European railway tracks, even the branch lines ! No rumbling, rocking, swaying, or anything there ! Just smoothness.

There is nothing wrong with putting in some kind of "psuedo" movement as long is it can be disabled for those that do NOT wish it to be present. Keep in mind the first point here!!!!

Absolutely. OR would become totally unusable if it "simulated" "cab-sway" in a Shinkansen, TGV or ICE train. There must be the option to turn it off completely.

[kox]

Absolutely. OR would become totally unusable if it "simulated" "cab-sway" in a Shinkansen, TGV or ICE train. There must be the option to turn it off completely.

Not true at all. EVERY vehicle have cab motion. Depending on the suspension and the quality of track. You seem to think cab sway is a fixed thing what's always the same... but in every game where it is implemented you can set track quality per track sections.

[GoGoran]

Not true at all. EVERY vehicle have cab motion. Depending on the suspension and the quality of track. You seem to think cab sway is a fixed thing what's always the same... but in every game where it is implemented you can set track quality per track sections.

Let's say it's below anything you could simulate on a computer screen, as far as European mainline railways are concerned.

[OTTODAD]

The quality of high-speed mainline tracks varies greatly in some European countries.

Has been a while since I have been a passenger in a French TGV from Paris to Lyons and in a German ICE-3 from Frankfurt and do not recall any sway in their carriages at all.

There certainly can not be any sway in the French AGV train which can reach speeds of up to 574 Kph, which is the world record !

On the other hand I am frequently riding on a UK Great Western Intercity HST from Bristol Parkway to Paddington and it is not until it gets past Reading that the ride gets smoother, not spilling the contents of full drinks cups on tables, speeds being restricted West of Reading and on some other UK mainlines since a HST derailment some years ago.

What is the sway like in the HST Acela Express on the NEC upgraded for it seamless, concrete ties tracks ?

I do much of my train simulator driving outside cabs and have not yet tested the few available in TS 2012 passenger views for swaying, I can do without one way or the other.

Like I have said before, lets have an option to turn it off altogether, which can be achieved partly in TS 2012 by reducing the programmed into tracks files unevenness to ZERO, but there is still some annoying jerking when the loco encounters an abrupt gradient change or a sudden change in the tilt at superelevated s-curves track joints !

O t t o

[GoGoran]

Best way to simulate cabsway: Rocking back and forth and sideways in your computer chair !

[mestevet]

There certainly can not be any sway in the French AGV train which can reach speeds of up to 574 Kph, which is the world record !

While I agree that the tolerances for lateral movement/sway that we engineers would refer to technially as "yaw" MUST be quite a bit higher to enable extremely high speeds safely, I don't agree that there "can not be any sway". That is simply an engineering impossibility. There will be sway as a consequence of the basic track and wheel structure even in the high tolerances held by the TGV and Shinkansen. Those trains DO go through curves, albeit banked and super-elevated, but simply heading into a curve, where one wheel MUST have higher lateral forces simply based on physics, there MUST be some amount of sway. It may be highly damped by active systems that make it difficult to notice, but there will be sway.

What is the sway like in the HST Acela Express on the NEC upgraded for it seamless, concrete ties tracks ?

I have been looking through my video to see if I can find a good example to illustrate the sway (yaw) and rock (pitch) that I've seen from an Acela power car going through a non-high speed interlocking (read: an interlocking that can handle "high speed" track speed, but NOT high speed through the diverge - I can't say, with good knowledge what the exact tolerances on all the components are, but certainly NOT anything like a true "high speed" turnout as would be used with the TGV). However, I have seen Acelas consistently hit the "Hook" interlocking in Marcus Hook, PA at about 110mph and as it hits the switches, start to see the engine rock (like nose to tail like a see saw) and also start to sway. It's actually pretty subtle, which is why my videos aren't clearly showing it, since I can't get that close to the interlocking itself (about 1/4 mile away at the train station) and it damps out (dies down and stops) within a couple hundred yards (my guess) and the power car is typically very smooth going through the station (the rock seems to damp out more quickly than the sway. The passenger cars themselves seem to display even less visible rocking/rolling/swaying, I'm guessing on account of the active damping systems being activated. I can't say what the power car motion would look like in the cab, but given what I'm seeing trackside, it doesn't strike me as alarming, it would probably look like a little bounce and a small side to side motion.

I've also been ON the Acela a number of times going through that same interlocking (and others, obviously) and in the passenger spaces barely notice it other than the sound changes a bit. I'm probably only one of few people who notice it just because I'm aware of the fact there is an interlocking there, and I'm paying attention to it. The ride on the normal, concrete tie and welded rail is silky smooth.


I do agree that, poorly implemented, this could be a huge distraction from an otherwise good physics simulation. My understanding of vehicle dynamics (my experience is mainly with aircraft, but many of the underlying principles are the same with rail and road vehicles) is that it can be quite complicated and will depend highly on an accurate model of the spring and dampening systems and the geometry of the suspension in a vehicle. Manufacturers use highly sophisticated dynamic modeling software packages to characterize the motions of their vehicles, and it's not simple science. If it can be boiled down to some simple things to be handled by a train simulator without losing realism, I'm all for it. But I agree the ability to "switch it off" is probably a wise way to go.

Steve