Rail Geometry Question
Discussion
Their must be some rail experts on here.
For reasons I won't go into, I could do with knowing something about rail geometry, and it's probably phenomenally simple!
Switch & control units - BV8 or 1 in 8 specifically. What is the actual curvature, because 1 in 8 is obviously a simple angle that would only give you a straight line? I basically want to draw it in CAD and need to understand how.
For reasons I won't go into, I could do with knowing something about rail geometry, and it's probably phenomenally simple!
Switch & control units - BV8 or 1 in 8 specifically. What is the actual curvature, because 1 in 8 is obviously a simple angle that would only give you a straight line? I basically want to draw it in CAD and need to understand how.
I'm not a rail expert, but in CAD the answer is surely self evident: if you draw a line 1 unit long, forming a right angle with a line 8 units long (or multiples thereof) then draw an arc that is tangential to the longer line at it's open end and intersects the end of the shorter line at its closed end, Bob's your uncle.
With AutoCAD, you could draw the arc using the <Arc: start/end/direction/> function to join the ends of your 1:8 straight lines.
If you can't grasp what I'm saying, let me know and I'll post up a simple diagram later.
With AutoCAD, you could draw the arc using the <Arc: start/end/direction/> function to join the ends of your 1:8 straight lines.
If you can't grasp what I'm saying, let me know and I'll post up a simple diagram later.
Just coming back to this, having drawn the curve in the above way, it gives a radius of 32.5m.
Now, I have reason to believe that this bv8 switch and crossing unit actually has a radius of 183.3m! Which begs the question of what the hell the 1:8 is referring to.
If anyone has any idea on this it would be very much appreciated.
Now, I have reason to believe that this bv8 switch and crossing unit actually has a radius of 183.3m! Which begs the question of what the hell the 1:8 is referring to.
If anyone has any idea on this it would be very much appreciated.
There is an S&C design handbook on the Network Rail system which has accurate dimension for each size switch and possible turnout radii.
Switches range from A-H? With A being the tightest radius layout, for very low speed, and H being very shallow radius layouts allowing faster speeds through turnouts.
Ideally you need a copy of NR/L2/TRK/2049, Page 17 - 35.
S&C design is massively complex.
Switches range from A-H? With A being the tightest radius layout, for very low speed, and H being very shallow radius layouts allowing faster speeds through turnouts.
Ideally you need a copy of NR/L2/TRK/2049, Page 17 - 35.
S&C design is massively complex.
Swervin_Mervin said:
Yeah and not something I really want to delve into JB!
I take my interpretation is correct though? That is to say that the 1 in 8 that is referred to is the angle you essentially end up on relative to the line you've just left?
every 8ft forward would be 1ft deviation basically.I take my interpretation is correct though? That is to say that the 1 in 8 that is referred to is the angle you essentially end up on relative to the line you've just left?
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