When the alignment is not at the CL of bridge

[phooi]

I am new in C3D, and my main concern is bridge modeler. I am using C3D 2014.

When I build the corridor, the CL of bridge is always on the top of alignment, but actually my alignment is at 3.65m rightward from CL.

Pls help.

Attached my dwg for your better understanding.

[ericcollins6932 · Accepted solution]

Then build an offset alignment from the CL alignment and have the corridor use that alignment instead as its target.

[phooi]

Thank you Eric, yes, now my corridor is able to locate at center.

I proceed with my modelling, and now come to another problem :

When I assign superelevation, the rotation axis is at the CL, can I make the rotation axis 3.65 rigthward from CL ? (as shown in attached picture)

[ericcollins6932]

Not in front of my computer, but if I remember, you typically rotate about either the inside or outside edge as per the super examples. Docs state do not include an offset in an assembly that that will be used with superelevation axis of rotation. The axis of rotation calculation will not run on an assembly that contains an offset.

[phooi]

Thanks for sharing your knowledge.

So sad that it cannot be done....

Just hope that Autodesk can add this functionality in the future releases.

What I need is to get the coordinates at left edge, right edge and CL of top surface of the bridge at every segment.

Then I try to use Lane assemby for my purpose, and it works.

Another problem occur:

The length of my assembly is 10.04m, but the length measured at the corridor become bigger, i.e. 10.041, 10.043, 10.047, 10.058, etc.

How can this happen ? Does it show the inaccuracy of the software ? or some setting is needed to fine-tune it ?

[nikoue · Accepted solution]

I think that you mesure dimensions using dynamic usc. The horisontal lenght of the your assembly is always 10.04.

Whats you mesure in the drawing is a sloped lenght which depends of the slope of the assembly.

H_Dist=Slope_Dist * Sin(angle)

You mesure the Slope_Dist. The H_Dist is always 10,04. 

[phooi]

I see, Thank you very much.

How if I want the sloped length always 10.04m, is it possible ?

[nikoue]

I can’t think an automatic way to do that.

Maybe you can built a custom subassembly in which you can make a parameter of a width witch user must key in e.g 10.04.

After that you can place a second parameter Width Slope with a formula Width_Slope= width/ sin(angle).

The angle is arctan(slope/100). So

Width slope=width/sin(arctan(slope/100)

I don’t know if it can read slope from superelevation.

Of course you can compute manually this width in every section and override it in the section editor.

But really I don’t know why you want that.

Maybe it makes sense in rail design. 

[fcernst]

You can make an API call for the superelevation in SAC, calculate your required projected subassembly width to effect your desired lane length, and pass that projected width back into the stock subassembly's width parameter. 

[phooi]

I think these should be the correct approach.

I still need some time to learn about how to create my own assembly using Subassembly Composer and API function.

Thank you very much !