JonMyrlennBailey
Active member
and vice-versa?
Often scale-model track is specified in radius and not degrees.
Often scale-model track is specified in radius and not degrees.
Is there a simple online calculator that will convert a curve radius to degrees....
- Thread starter JonMyrlennBailey
- Start date
No. Radius refers to any segment of the curve, angle refers to a specific segment. You can't convert one to the other.
JonMyrlennBailey
Active member
No, I had this in mind and this is what is used in railroad construction:
https://en.wikipedia.org/wiki/Degree_of_curvature
Degree of curve or degree of curvature is a measure of curvature of a circular arc used in civil engineering for its easy use in layout surveying.
Rolling stock have minimum curve specifications due to mechanical limitations in the travel of the couplers and the rotation of the bogies.
An SD40-T-2, 70.80 feet long, 3-axle trucks, loco requires a curve radius of a minimum of 359 feet when coupled to another piece of rolling stock but only 197 feet if traveling by itself.
I have curves as tight as 75 meters/245 feet on my Trainz layout and coupled SD40-T-2's handle them well at speeds of 25 mph or less. On these tighter turns, it appears as if the couplers between two such engines are disconnected while viewing them from the top down but they are not so tight that the loco bodies, the end porches, touch one another on the turns.
An O-scale Pullman Heavyweight car by Lionel requires a curve radius minimum of 54". This car sports a long wheelbase and 3-axle trucks.
On some HO layouts, if the curves are too tight, rolling stock won't auto-couple on them.
https://en.wikipedia.org/wiki/Degree_of_curvature
Degree of curve or degree of curvature is a measure of curvature of a circular arc used in civil engineering for its easy use in layout surveying.
Rolling stock have minimum curve specifications due to mechanical limitations in the travel of the couplers and the rotation of the bogies.
An SD40-T-2, 70.80 feet long, 3-axle trucks, loco requires a curve radius of a minimum of 359 feet when coupled to another piece of rolling stock but only 197 feet if traveling by itself.
I have curves as tight as 75 meters/245 feet on my Trainz layout and coupled SD40-T-2's handle them well at speeds of 25 mph or less. On these tighter turns, it appears as if the couplers between two such engines are disconnected while viewing them from the top down but they are not so tight that the loco bodies, the end porches, touch one another on the turns.
An O-scale Pullman Heavyweight car by Lionel requires a curve radius minimum of 54". This car sports a long wheelbase and 3-axle trucks.
On some HO layouts, if the curves are too tight, rolling stock won't auto-couple on them.
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cascaderailroad
New member
You measure a curve radius in Google Earth, and apply that same measurement into the Trainz ruler … nothing scientific about it … laying a curve (lead in/lead out, easement) is a piece of cake … Trainz doesn't need roket' sientist' to know when your U50 is running on a 75 m radius curve, it is obvious, by eye when a curve is too tight
You are factoring in way too much obsessive compulsiveness into a model train simulator video game cartoon illusion called Trainz, that will run a BigBoy locomotive on a 10 m radius curve, and still not derail
It's not really real … it's just a video Game, man
You are factoring in way too much obsessive compulsiveness into a model train simulator video game cartoon illusion called Trainz, that will run a BigBoy locomotive on a 10 m radius curve, and still not derail
It's not really real … it's just a video Game, man
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If that site describes what you mean be 'degree' then that is degree of curvature, which is not the angle usually specified for model track. The formulae are available from that site. You just have to nominate either the arc length or the chord length. You haven't indicated which you want to use. See: https://rechneronline.de/pi/circular-segment.php
JonMyrlennBailey
Active member
I wanted use what's used on American railroads as a standard.
For example, what standard for tightness of curves would Union Pacific employ on standard-gauge track?
For example, what standard for tightness of curves would Union Pacific employ on standard-gauge track?
I recommend contacting the UPRR historical society. They would have information, or most likely know of sources for that information.
cascaderailroad
New member
Again … Go on Google Earth … And measure a radius of a tight mainline curve … and apply that measurement into Trainz
Minimum arc radius and spline spacing
This is what I use in my routes:
R = 250, Vmax = 20
R = 400, Vmax = 30
R = 500, Vmax = 35
R = 600, Vmax = 40 (tightest arc allowed for welded tracks)
R = 800, Vmax = 50
R = 1200, Vmax = 60
R = 1500, Vmax = 60 (as R = 1200, but causing less stress on rolling stock)
R = 2000, Vmax = 70
R = 4000, Vmax = 100
Where
R is arc radius in meters
Vmax is maximum speed in miles per hour
To avoid shaky movement of the train on the curve section of track, I insert splines no further than in this intervals:
R = 250, α = 18
R = 400, α = 14
R = 500, α = 12
R = 600, α = 11
R = 800, α = 9
R = 1200, α = 8
R = 1500, α = 7
R = 2000, α = 6
R = 4000, α = 4
where α is the angle of circular sector in degrees.
These figures are based on experiences from Central and Eastern European railways.
This is what I use in my routes:
R = 250, Vmax = 20
R = 400, Vmax = 30
R = 500, Vmax = 35
R = 600, Vmax = 40 (tightest arc allowed for welded tracks)
R = 800, Vmax = 50
R = 1200, Vmax = 60
R = 1500, Vmax = 60 (as R = 1200, but causing less stress on rolling stock)
R = 2000, Vmax = 70
R = 4000, Vmax = 100
Where
R is arc radius in meters
Vmax is maximum speed in miles per hour
To avoid shaky movement of the train on the curve section of track, I insert splines no further than in this intervals:
R = 250, α = 18
R = 400, α = 14
R = 500, α = 12
R = 600, α = 11
R = 800, α = 9
R = 1200, α = 8
R = 1500, α = 7
R = 2000, α = 6
R = 4000, α = 4
where α is the angle of circular sector in degrees.
These figures are based on experiences from Central and Eastern European railways.
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Christopher824
CDETrainz.com
Its too hard to work it out that way (or maybe impossible according to the other posters), determine your radius, then break it up into degrees with the ruler, then do the math in your head.
Then the outcome is like this...
Based on my conversations with a MOW engineer, the degrees of curvature are based on a 100 foot chord. Additionally according to him, in jointed rail with 39 ft rail lengths, on the inside rail, you can run a string line across two rails from the ends, and the inch measurement will be the degrees curvature.
Christopher824
CDETrainz.com
What you speculate is a little more complex than using a string.
See here https://mysite.du.edu/~jcalvert/railway/degcurv.htm
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It is not too hard if you know the method and once you know it you will never be happy to work by trial and errors.
The method shown on your screenshots is very accurate and I use it myself, but only for tight arcs, with radius up to 500 meters. This method is impractical for arcs with high radius, like 2000 meters and higher. You would need to add many temporary base boards just to plot the arc center (which is required in your method). In my method (described here https://forums.auran.com/trainz/showthread.php?150917-Is-there-a-simple-online-calculator-that-will-convert-a-curve-radius-to-degrees) you don't need to plot arc center, because you lay track using straight fixed track turned by the required angle of an arc sector. This method is not as accurate (it would if the arrow tool was better designed), but still results in fair accuracy of plus minus 5% (which is optically undetectable).
When I start building my next route I post some pictures here.
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Christopher824
CDETrainz.com
Why would it be different for a bigger arc. Math is math... https://mysite.du.edu/~jcalvert/railway/degcurv.htm
Just add some more baseboards until you can complete your arc.
GoofusClam57
Member
I may have missed it, but in reading through this topic, I did not see an answer to the original poster's question, a simple online calculator to convert curve measures in radius to their equivalent measure in degrees. If I did the algebra correctly, the formula would seem to be 2 x ArcSin(50/Radius) = Degree, if the Radius is measured in feet. For meters, this becomes 2 x ArcSin(15.24/Radius) = Degrees. So, the calculation is simple, if not online. Make sure your calculator isn't set to use Radians.
The original question cannot be answered. OP wanted to convert the radius used to describe model railway curved track section to degrees. It can't be done without knowing other dimensions, and manufacturers typically supply a variety of sections.
If, instead, OP wanted to convert a length of arc (not a radius) such as the typical US railway standard of 100 to a degree of curvature then the formula is available at the sites referred to in some of the posts.
GoofusClam57
Member
Ooooh! So OP was asking how many degrees of turn would one get from a section of Atlas 18" radius track, for example? That is different from the question I was attempting to address. Thanks for the clarification!