> 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/examples/steel-bridge-examples/example-steel-tub-girder-bridge-ex1-stg/bridge-geometry-ex1-stg.md).

# Bridge Geometry

This section defines the geometric layout of the Steel Tub Girder Bridge including alignment, supports, and girder positions.

{% hint style="info" %}
**Navigation:** Bridge Geometry
{% endhint %}

## Overview

Bridge geometry establishes the spatial framework for the entire model:

* **Roadway Alignment:** Horizontal, vertical, and transverse geometry
* **Bridge Alignment:** Associates alignment with the bridge
* **Support Lines:** Defines abutment and pier locations
* **Insertion Points:** Positions for girder placement
* **Girder Layout:** Connects insertion points to define girder paths

## Sections

| Section                                                                                                                                           | Description                                          |
| ------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------- |
| [Roadway Alignment](/examples/steel-bridge-examples/example-steel-tub-girder-bridge-ex1-stg/bridge-geometry-ex1-stg/roadway-alignment-ex1-stg.md) | Define horizontal curves, grades, and cross-sections |
| [Bridge Alignment](/examples/steel-bridge-examples/example-steel-tub-girder-bridge-ex1-stg/bridge-geometry-ex1-stg/bridge-alignment-ex1-stg.md)   | Assign alignment to bridge                           |
| [Support Lines](/examples/steel-bridge-examples/example-steel-tub-girder-bridge-ex1-stg/bridge-geometry-ex1-stg/support-lines-ex1-stg.md)         | Define abutment and pier stations                    |
| [Insertion Point](/examples/steel-bridge-examples/example-steel-tub-girder-bridge-ex1-stg/bridge-geometry-ex1-stg/insertion-point-ex1-stg.md)     | Position girders on support lines                    |
| [Girder Layout](/examples/steel-bridge-examples/example-steel-tub-girder-bridge-ex1-stg/bridge-geometry-ex1-stg/girder-layout-ex1-stg.md)         | Connect insertion points for girder paths            |

{% hint style="success" %}
Complete Bridge Geometry before defining Properties and Superstructure components.
{% endhint %}


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