> For the complete documentation index, see [llms.txt](https://docs.openbrim.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openbrim.org/templates/cadd/stationoffset-cadd.md). # Station Offset A **Station Offset** labels a point's location relative to an alignment as a Station + Offset pair: how far along the alignment the point sits, and how far perpendicular to it. This is the standard way to call out the location of bridge features in plan — pier centerlines, abutment back walls, bearing centerlines, expansion joints, drainage pickups, sign foundations. Pick a point, and the label shows its `Station` (distance along the alignment from the alignment start) and `Offset` (perpendicular distance from centerline; positive = right of stationing, negative = left). Before the first pick, the label the pick would make is drawn faintly at the cursor and the prompt reads it, so the right station can be found by moving the cursor. ## The picked point The first pick lands on a vertex of the cut, or on an alignment line the cut draws. Alignment lines are snap targets: nearest, perpendicular and intersection snaps land on them (for example where the alignment crosses a pier joint), and their ends and major station ticks snap as endpoints. * **On an alignment line**, the point is held by alignment and station. It stays at that station when the alignment or the cut changes; it marks a station, not the support it was picked at. * **On a vertex of the cut**, the point is bound to that point of the cut (Source Object, Layer, Point Index) and follows it when the model changes. The Layer is the drawing the point was picked on (CL, Cut or Proj); the point is held as what it is in that drawing -- a centerline's First or Last point or its cross Marker, a cut's named corner (TL, BL, TR, BR, T, B), a Corner, the Middle of a straight side, a plumb point straight above or below a corner or a middle (Above Corner 7, Below Middle 4; in a cross section or an elevation), a Mid-edge point or a Vertex -- so a point added or removed in another tier (a new corner, a chord more or less) does not move it to another point; only a change in its own tier before it renumbers it. Named corners and a centerline's First and Last are found by position each time, so a large enough change of the shape can move them: a wider bottom flange can take TL. While picking, the snap marker says what the pick would hold, in the sheet's words ("Deck1 Cut TL", "PIG1\_1 CL Last", "PIG1\_1 CL Marker 2", "Deck1 Cut Middle 4", "Deck1 Cut Above Corner 7"), and on an alignment line the alignment and the station ("US380ML, STA 1064+81.81"). **Attached Alignment / Attached Station:** The alignment and station a point picked on an alignment is held at. Type a station (`160` or `1+60`) to move the point along the line; dragging the point grip slides it along the line, and dropping it on a model point binds it there. **Source Object / Layer / Point Index / Point:** The point of the cut a point picked on a vertex is bound to. Layer (read-only) is the drawing it was picked on; Point (read-only) names it ("TL", "Mid 18", "Marker 2"); Point Index takes a number in the point's tier or a name ("TL", "Corner 7", "Middle 4", "Above Corner 7", "Mid 3", "Vertex 12", "First", "Last", "Marker 2") to hold another point of the same object. ## Alignment **Alignment:** The alignment the station and offset are measured from; empty means the cut's own. Chosen in the tool's input bar before the first pick, or in the sheet. A named alignment that is deleted shows "--" in the broken-reference colour and "(not found)" in the sheet; a renamed one is followed. **Show Alignment Name:** Adds a third line naming the alignment measured from, for projects with more than one alignment. **Alignment Name Prefix:** Text before that name; default `℄` . DXF and DGN write `℄` as `CL`. ## Text **Label:** Override text. Leave blank for the auto-computed `STA , OFF ` format. **Precision:** Number of decimal places. ## Placement **Offset X / Offset Y:** Leader offsets — fine-tune label position relative to the dimensioned point. ## Typography **Text Height:** Text size in real units. **Font Family / Font Weight / Font Style:** Font controls. ## Notes Station Offset annotations are essential on plan-view bridge drawings — every bearing centerline, pier centerline, joint location, and drainage pickup typically gets one. A label bound to a model point updates when the alignment is revised or when that point moves (a pier repositioned, a bearing moved). A label held on an alignment keeps its station: to follow a support that moves, pick a vertex of the support instead. A label whose text sits to the left of its point is right-aligned at the end of its leader. Station format follows highway conventions (e.g., `STA 12+34.50` for stations using the `+` separator), or the project's preferred format. The exact format depends on the alignment's stationing setup. For features that share a station but sit at multiple offsets (e.g., a row of bearings on one pier line), call out the station once and use Linear Dimensions for the offset spacing — cleaner than a Station Offset on every bearing. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. 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