A completed Location design contains a horizontal alignment and a vertical alignment that define the designed road center line coordinates; this designed line is referred to as the Location line or L-line or simply the Alignment.
An optional traverse document (TR1 file) contains a centerline and perpendicular side shots that define a ribbon of topography; the traverse center line is referred to as the preliminary line or P-Line.
If a P-Line traverse exists, it is possible to refer to position either by P-Line Station (distance along the P-Line traverse) or by L-Line Station (distance along the horizontal alignment).
