View Full Version : Looking for tips to determine a speed limit

jcardana

August 27th, 2012, 05:39 PM

I'm throwing together a fictional route. Some of my curves seem pretty sharp but at 70+ mph (with derailment set to realistic) the train stays on the track.

Does anyone use some kind of guide to determine a speed around a curve. For example... at 67mph my loco derails on a 25 curve but not on a 35.

Just curious.

Thanks,

Joe

Ricke82

August 27th, 2012, 07:46 PM

See Appendix A in 49 CFR, Part 213 for current US regulations: http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div5&view=text&node=49:4.1.1.1.8&idno=49

Since track in Trainz is not super-elevated, the speeds listed in the 0 column would be appropriate. If you need to convert Degree of Curvature to a curve radius you can use the Area 10 Spiral Calculator applet found here: http://home.comcast.net/~daletherail/curve/curveHome.html. The Spiral Length and Total Central Angle don’t matter in this case. Since you’re not doing a transition curve, the Number of Spiral Stations would be 1.

For example if you’re using a 1 degree curve (a radius of 5,729.651 feet), the maximum allowed speed would be 66 mph. That’s assuming that it’s Class 5 track for freight or Class 4 or 5 for passenger trains. Obviously, if the maximum allowed speed for the class of track is lower than the speed allowed for the curve, the former would be the governing factor. In the above example if it was Class 2 track the maximum speed would be 25 mph (not 66 mph).

Or, since this is your route and (at least so far) the Code of Federal Regulations do not apply, you can just use whatever looks right to you.:D

JCitron

August 27th, 2012, 09:19 PM

I determine the speed by going for a ride. If the train makes me seasick when going around the curves, I slow the speed down. ;)

John

jcardana

August 27th, 2012, 10:20 PM

I determine the speed by going for a ride. If the train makes me seasick when going around the curves, I slow the speed down. ;)

John

That's what I've been doing and I'm bored with it.

jcardana

August 27th, 2012, 11:07 PM

Ricke82: Cool! Thanks! I think that will work!

jcardana

August 27th, 2012, 11:55 PM

Thanks to Ricke82 pointing me in the right direction... This formula seems to correspond to what he showed me

Speed(mph) = SQRT( (30*CurveRad(m) / 11.8)

meters = ft * .3048

kph = mph * 1.609344

So when Trainz gives me a Curve Radius of 40, I can calculate that 10mph is the limit.

jcardana

August 28th, 2012, 02:13 AM

I've also come up with a way to determine the overall curve radius... Taking the smallest number closest to the spline points and divide by .63. The take the largest number in the middle of the curve and divide by 1.3. Both numbers should be close to average together.

airtime

August 28th, 2012, 04:01 AM

I've also come up with a way to determine the overall curve radius... Taking the smallest number closest to the spline points and divide by .63. The take the largest number in the middle of the curve and divide by 1.3. Both numbers should be close to average together.

Now your just showing off...:hehe:

Good logic though, if I can get my head around it...:confused:

Joe Airtime

jcardana

August 28th, 2012, 09:49 AM

If I was showing off... I'd tell people that I created a Windows App that did all this for me... but I don't want to show off, so I won't say that! :o

OK, ok... for those interested... you can get the calculator HERE (http://www.anadrac.com/Downloads/TrainzSpdCalc.zip)

kws4000

August 28th, 2012, 02:18 PM

See Appendix A in 49 CFR, Part 213 for current US regulations: http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div5&view=text&node=49:4.1.1.1.8&idno=49

Thanks a BUNCH! Never knew where to find that stuff before, but now I've learned somthing, which means I had to forget something to make room for it....:)

JCitron

August 28th, 2012, 08:38 PM

If I was showing off... I'd tell people that I created a Windows App that did all this for me... but I don't want to show off, so I won't say that! :o

OK, ok... for those interested... you can get the calculator HERE (http://www.anadrac.com/Downloads/TrainzSpdCalc.zip)

This is much better than going for short boring rides and getting seasick. :)

Thank you for the link to your app.

John

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