Curve Dimensions

Has anyone published dimensions for the various curve sections in MSTS. For example, I assume that a 1000r curve section means 1000m radius to the centerline? But what about the a2, a3 and a4 sections? Is the 1000m to the inside track centerline or elsewhere? And, is the standard MST spacing between multiple tracks exactly 5m, or is it really 5.xxxxx?Along the same lines, I often find myself needing a particular curve radius that is not available in the a2 or higher numbers of tracks. For example, I have a 150r, three track curve to lay. I can lay one of the tracks with an a1t150r section, but then must fit the other two tracks using dynamic sections. Of course this requires a bit of trial and error. I wonder if anyone has taken the trouble already to figure out what the right dynamic settings are for such cases. It sure would be a timesaver.Thanks

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RE: Curve Dimensions, DKT, May-26-04, 03:09 PM, (1) RE: Curve Dimensions, OkrasaGhia, May-26-04, 03:26 PM, (2) RE: Curve Dimensions, muskokaandtahoe, May-27-04, 12:17 PM, (3) RE: Curve Dimensions, rmays, May-28-04, 11:29 AM, (4) RE: Curve Dimensions, OkrasaGhia, May-28-04, 12:17 PM, (5) RE: Curve Dimensions, rmays, May-30-04, 01:58 AM, (6) RE: Curve Dimensions, OkrasaGhia, May-30-04, 11:02 AM, (7) RE: Curve Dimensions, rmays, May-31-04, 11:58 AM, (8)

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Go to http://www.railpage.org.au/steam4methen look at their excellent tutorials, they have just what you need there.
Whish there were more sites like steam4me.DKT

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steam4me is great with all kinds of tutorials.
When it coems to track I also have some info at the XTracks site http://www.xtracks.tk.
For a2t 1000m is between the tracks, a3t it is the middle track and a4t it is 1000m between tracks 2 & 3. The standard MSTS spacing is actually 4.985m (don't ask me why, it just is).
For the case with a1t150r tracks your outer dynamic track would need the radius 150+4.985m and the inside dynamic track needs to be 150-4.985m radius. The angle value is a simple recalculation between degrees and radians (which is what dynamic tracks use, again don't ask me why).
Radians = 3.14159 * degrees / 180
5° = 0.08727 radians
10° = 0.17453 radians
20° = 0.34907 radians


//Okrasa
Chief Engineer
okrasa @ xtracks.tk
http://www.geocities.com/okrasaghia
http://www.xtracks.tk

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I used to think it was because it would be easier to calculate position for the moving train but now I'm leaning towards the simple explanation that conforms more closely to the evidence we have from elsewhere of the way Kujo developed the sim: the left hand knew nothing of the right.Dave NelsonWP mainline, Oakland-Stockton: 100% complete;
SP mainline, Oakland-Stockton: 20% complete;
Aug 1950
<<new .sig under construction>>

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OkrasaThanks for the data. I have seen the information on your site as well as steam4me, and it is really good stuff. What I really needed was the parallel track spacing and radii, which you kindly gave in your response. This does indeed make lining up the dynamic sections easier.However, one thing I have noticed is that if I try to take a dynamic track through too many degrees of curvature, it will not connect to the adjoining track. For a single curve I have found that adding a 2m straight middle section solves this problem, but of course also slightly changes the dynamic curve radius.

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There is an upper limit to both the curvature (90°) and the radius (2000m) of dynamic track (that can be overcome by manually editing it in the w-file) but I have not heard about any connection problems before.
I don't use much dynamic track thus it could be another strangeness that Kuju managed.


//Okrasa
Chief Engineer
okrasa @ xtracks.tk
http://www.geocities.com/okrasaghia
http://www.xtracks.tk

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OkrasaThanks for the information. The connection problem is really odd. Sometimes it connects, sometimes it doesn't. It always works with the short straight piece inserted. I wonder if it has to do with sloping track. I am building the B&O West End, Cranberry Grade section as it was in the 1960's, which means 20 km of 2.5%+ grades and tight curves on a 3-track main line. Because of the tight curves in many places I have had to use the tighter radius a1 or a2 sections and then finish the 2nd and/or 3rd tracks with dynamic pieces. As a result the dynamic pieces always have a significant slope.By the way, thank you very much for the XTracks work. It has added much more potential to route design.Ron

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Okay, sloping curving track built with separate sections for each track means some additional problems you might not think about. Since the outside track in a curve is actaully slightly longer you can't use exactly the same grade or you will have height differences at the end of the track sections. This is because the tilt is set at the start of the curve. Think of a 90° curve and tilt it at the start and you will understand what I mean. The end of the outside track will be elevated more than the inside track. To get it right you will need to use an a3t or a4t track section at the end and match each tracks angle to fit using the 'End' key to fine tune the angle.
You do know about the 'End' key? Hold it down while adjusting the angle and you can adjust it by 1/1000s instead of 0.15s.


//Okrasa
Chief Engineer
okrasa @ xtracks.tk
http://www.geocities.com/okrasaghia
http://www.xtracks.tk

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OkrasaAgain, excellent input. Yes indeed I ran into the height mismatch problem early on, so I have been doing just as you suggest. I put a 3 track 10m section at the end of the curve to make sure I get the right alignment, and use the end key as you describe to fine tune the rail height for a match.For other readers of this string I have learned another trick to make this "cut and try" approach a little faster. After I run the dynamic curve to the other end, I do the rough slope adjustment using just the F4 key and with the ground texture visible. Then I raise or lower the track until it just appears above the ground surface. As a result the rail height mismatch is never off by more than the height of the rail. And the real payoff is that the final matchup on the radius seldom needs any adjustment.I have also learned the hard way that you should not take the dynamic curve through too many degrees when it slopes. When you go too far, instead of a nice even rising slope on the dynamic curve, you get a dip in the middle instead. By trial and error I have learned that running no more than about 50 degrees avoids this problem.I am also quite sure there are other tricks I have not learned yet. As old as this software is it is amazing that there is still so much to learn.Ron

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