# Insertion Point \[TB]

Insertion points define discrete locations on a support line where bearings, truss nodes, girder ends, or deck anchors attach to the bridge geometry. In the Truss Bridge workflow, an insertion point may also serve as a truss bearing or as an arch bearing point.

## Bridge Parameters

**Location:** The support line that carries this insertion point. Click the cell and use **Set to ... (Support Lines created)** or **Select** to pick a previously defined support line; the station, skew, and transverse offset of that support line govern where the insertion point can be placed.

**Longitudinal Offset:** Offset along the PGL (Profile Grade Line), measured from the support-line station. Positive values move the point up-station. When the support line has a non-zero skew, the longitudinal offset is applied perpendicular to the support line.

**Transverse Offset:** Offset along the support line (not along the PGL). Zero places the insertion point at the center of the support line, a positive value offsets toward the right when looking up-station along the PGL, and a negative value offsets toward the left.

{% hint style="info" %}
The positive direction of the Y-axis is to the left when looking up-station along the PGL. However, based on engineer feedback, OpenBrIM's transverse-offset convention uses **positive = right** when looking up-station. This sign convention applies to geometric offsets; FEM load definitions still follow the standard Y-axis rule (positive Fy = left).
{% endhint %}

**Reference Object \[Girder Layout/Steel Bent/Truss/Deck]:** Identifies which object class the insertion point is paired with. Use **Girder Layout** for standard bearing locations at the end of spans, **Steel Bent** for connections feeding a steel bent cap, **Truss** for truss bearing/joint anchors, and **Deck** for deck-edge anchors. The selection controls how the insertion point participates in FEM generation and elevation computation.

**Reference Alignment \[Bridge Alignment (Default)/Custom Alignment]:** The alignment used to compute the insertion point's geometry. By default the bridge alignment (PGL) is used; switch to **Custom Alignment** if the hosted element follows a different path than the PGL.

**Custom Alignment:** When **Reference Alignment** is set to Custom Alignment, pick the alignment object to use. Required under that condition.

**Elevation:** Vertical elevation used when **Reference Object** is **Truss** — the truss bearing point is placed at this absolute elevation relative to the alignment, where zero is the PGL and negative values drop below the PGL. Only active when the reference object is Truss.

**Station on PGL (readonly):** Displays the computed station of the insertion point projected onto the PGL. (Read-only)

**Distance Perpendicular to PGL (readonly):** Displays the perpendicular distance from the insertion point to the PGL, using OpenBrIM's convention (positive = right of PGL looking up-station). (Read-only)

**Elevation (readonly):** Displays the computed global elevation of the insertion point — for Girder Layout / Deck references this combines the bearing location with the alignment's vertical and super-elevation profiles, and for Truss references it echoes the user-entered Elevation. (Read-only)

## Referencing Objects

**Bearing Fixities:** Bearing Fixity objects that reference this insertion point. An insertion point may carry at most one bearing fixity. (Read-only)

**Girder Layouts:** Girder Layout objects that reference this insertion point. (Read-only)

**Girder:** Girder objects (from girder layouts) that land on this insertion point. (Read-only)

**Structure States:** Construction/deconstruction state objects that reference this insertion point. (Read-only)

**Bridge Seat:** Bearing Seat objects that reference this insertion point. (Read-only)

**Temporary Support:** Temporary Support objects that reference this insertion point. (Read-only)

**Truss:** Truss objects that reference this insertion point. (Read-only)


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