> 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/truss-bridge-workflow/substructure-tb/abutment-system-tb/drainage-tb.md).

# Drainage \[TB]

Bridge drainage is part of the engineering system that is used to capture, manage and drain surface water from the bridge surface.

## General

**Abutment:** This parameter specifies the abutment for which the drainage will be modeled.

**Elevation Offset from Bottom:** This parameter is used to determine the value of the elevation offset for the drainage object. The reference point is the bottom elevation of the abutment.

**Drainage Section:** This parameter is used to determine the section of the drainage object.

## Mid Drainage

**Mid Drainage Length:** This parameter is used to determine the length of the middle section of the drainage object.

**Mid Drainage Elevation Offset from Bottom of Abutment:** This parameter is used to determine the value of the elevation offset for the mid drainage object. The reference point is the bottom elevation of the abutment.

## Left Drainage

**Left Drainage Start Station:** This parameter is used to determine the starting station of the left-side drainage object.

**Left Drainage End Station:** This parameter is used to determine the ending station of the left-side drainage object.

**Left Drainage Offset from Front Face of Abutment:** This parameter is used to determine the value of the elevation offset for the left drainage object. The reference point is the bottom elevation of the abutment.

## Right Drainage

**Right Drainage Start Station:** This parameter is used to determine the starting station of the right-side drainage object.

**Right Drainage End Station:** This parameter is used to determine the ending station of the right-side drainage object.

**Right Drainage Offset from Front Face of Abutment:** This parameter is used to determine the value of the elevation offset for the right drainage object. The reference point is the bottom elevation of the abutment.

## IFC

**Type:** The IFC entity type for BIM export. Default is IfcDistributionSystem.

**Predefined Type:** The IFC Predefined Type is specified using this parameter. Default is DRAINAGE for bridge deck drainage systems. Available options include:

* DRAINAGE (default)
* DISPOSAL
* RAINWATER
* SEWAGE
* STORMWATER
* WASTEWATER
* USERDEFINED
* NOTDEFINED

**Parent \[Bridge/Superstructure/Deck/Substructure/Foundation/Approach\_Structure/Retaining\_Structure]:** The IFC Parent is specified using this parameter to define the hierarchy relationship in the IFC model.


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