Curve widening of Mainlines

Question

As shown in the attached image, i got one CAD file with this type of proposal. These lines are (Magenta colored lines) designed in MX software. Here the curves are widened to maintain concentric circles with the common circle centers with minimum distance between tracks as desired by client. When i try to translate MX XML file with Land XML Translator into .Alg format, it is not detecting those lines. The concentric circles has been maintained by providing some kink in the transition portion. 
 My doubts are is it standard practice everywhere to provide curve widening? 
 Is there any metro projects with this kind of phenomenon? 
 Is there any facility in Power Rail Track (SS-2) to convert these kind of XML files into Alg format? 
 The shift is around 0.3 to 0.4m after widening. Please any one clarify with your answer based on your experience. 
 
 Thanks in advance 
 Rajendra

jpln · Accepted Answer

In MX or Rail Track you can't create a true geometry element that is a linear offset of a clothoids to introduce the widening.
It is a long time since I last used MX but as far as I know MX, by default, is not able to create an alignment with kink. You have to activate the "non collinear" option.
I suppose that the 2 lines result of an offset from the centerline are only 3D strings not alignments, and you confirmed that they have been created using DESIGN command.
So the LandXML translator doesn't understand these lines as alignment but as features (answer of 2. 4. and 5.).

I think you don't have any spiral for the offset lines but segments (answer of 5.). And again no way to get a spiral by a linear (or other type of variation allowed by MX) variation of the offset along a spiral. So no tangency and no geometry (answer 1.).

Curve widening function does exist in Rail Track within corridor modelling (answer 3.).

As an alternative, still using corridor modelling, you can also change the offset by using parametric constraints (the width). Typically you have a template made of 3 points LT <-L_Width-> CL <- R Width -> RT and set the value of L_Width and R_Width by stations. (MX likes with input files).
You can also create longitudinal features along the alignment using offset and variation of offset (MX likes using design functions) using surface>Design surface commands. Certainly less used that corridor modelling.

jpln · Answer

Sorry no picture attached. 
yes it is common to have widening in curves. You can parallel alignments with offset using Rail Track. Arcs are concentric, straights are parallel and transitions are computed between the 2. 
How did you create these lines in MX. Are they alignments (M/G) or only strings created by DESIGN commands? 
If they are only strings that is why you don't get them as landXML import of alignment of only as lines.