> 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/concrete-box-girder-bridge-workflow/bridge-geometry-cbg.md).

# Bridge Geometry \[CBG]

OpenBrIM provides different workflows for each type of bridge. All objects are pre-defined and parametric, allowing users to create a model by defining several parameters. Due to the nature of parametric modeling, the requirements for defining parameters may vary. Definitions can be made using numbers, other parameters, or by choosing from provided options.

To obtain the desired model, a specific sequence must be followed, known as the workflow.

The common starting point for all workflows is Bridge Geometry.

The definitions for Bridge Geometry are divided into five main parts: Roadway Alignment, Bridge Alignment, Support Lines, Insertion Points, and Girder Layout.

**Roadway Alignment:** The alignment should be defined in the horizontal, vertical, and transverse directions or can be imported.

**Bridge Alignment:** The need to set Bridge Alignment to the previously defined Roadway Alignment is due to the requirement for the platform to allow users to have several alignments and several bridges within the same project.

**Support Lines:** Generally, the support lines in OpenBrIM are used when defining the locations of piers, abutments, and bearings.

**Insertion Points:** Insertion Points are needed to define bearing locations more specifically.


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