Hi Steve, yeah probably what you are running into there is if you have a high number of lines like that you probably have many of them that are within tolerance of being considered tangent to one another.

Segments that are considered tangent to each other will get kind of glommed together into longer rail pieces. It would probably be better for that rail segment combining stuff to not happen when the segments are lines.

If you had somewhat fewer lines so that they were not within such a close angle of being tangent to one another you might get a more expected result.

If you could post the 3DM model files of your examples I could test them over here and see if tuning up the rail segment combining solves the problem you are showing or not.

- Michael