New alignment and need for stations and offsets

@stefan.markic @Benzcly
In the US, road infrastructure is based on stations and offsets relative to the alignment. How is that now handled in the changes made in RC2?

If you mean how to specify such geometry, I’d suggest using IfcSectionedSurface or IfcSectionedSolidHorizontal. Note, though, that these are still in the finalization stage.

If you mean positioning elements along the alignment, I’d use IfcLinearPlacement.

I’m newbie at IFC but I’ll give a response I think is helpful.

The IfcAlignment2DHorizontal (4x1) and IfcAlignmentHorizontal (4x3rc2) have a StartDistAlong attribute. My guess is this attribute is defines starting station of the alignment.

Since an alignment is a distance along/offset coordinate system the range of distance along values is StartDistAlong to StartDistAlong+Sum of length of each IfcAlignment2DHorizontalSegment.