---
name: v.net.bridge
description: Computes bridges and articulation points in the network.
keywords: [ vector, network, articulation points ]
---

# v.net.bridge

Computes bridges and articulation points in the network.

=== "Command line"

    **v.net.bridge**
    **input**=*name*
    **output**=*name*
    [**arc_layer**=*string*]
    [**node_layer**=*string*]
    [**arc_column**=*name*]
    [**arc_backward_column**=*name*]
    [**node_column**=*string*]
    **method**=*string*
    [**--overwrite**]
    [**--verbose**]
    [**--quiet**]
    [**--qq**]
    [**--ui**]

    Example:

    ```sh
    v.net.bridge input=name output=name method=bridge
    ```

=== "Python (grass.tools)"

    *grass.tools.Tools.v_net_bridge*(**input**,
        **output**,
        **arc_layer**=*"1"*,
        **node_layer**=*"2"*,
        **arc_column**=*None*,
        **arc_backward_column**=*None*,
        **node_column**=*None*,
        **method**,
        **overwrite**=*None*,
        **verbose**=*None*,
        **quiet**=*None*,
        **superquiet**=*None*)

    Example:

    ```python
    tools = Tools()
    tools.v_net_bridge(input="name", output="name", method="bridge")
    ```

    This grass.tools API is experimental in version 8.5 and expected to be stable in version 8.6.

=== "Python (grass.script)"

    *grass.script.run_command*("***v.net.bridge***",
        **input**,
        **output**,
        **arc_layer**=*"1"*,
        **node_layer**=*"2"*,
        **arc_column**=*None*,
        **arc_backward_column**=*None*,
        **node_column**=*None*,
        **method**,
        **overwrite**=*None*,
        **verbose**=*None*,
        **quiet**=*None*,
        **superquiet**=*None*)

    Example:

    ```python
    gs.run_command("v.net.bridge", input="name", output="name", method="bridge")
    ```

## Parameters

=== "Command line"

    **input**=*name* **[required]**  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Or data source for direct OGR access  
    **output**=*name* **[required]**  
    &nbsp;&nbsp;&nbsp;&nbsp;Name for output vector map  
    **arc_layer**=*string*  
    &nbsp;&nbsp;&nbsp;&nbsp;Arc layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *1*  
    **node_layer**=*string*  
    &nbsp;&nbsp;&nbsp;&nbsp;Node layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *2*  
    **arc_column**=*name*  
    &nbsp;&nbsp;&nbsp;&nbsp;Arc forward/both direction(s) cost column (number)  
    **arc_backward_column**=*name*  
    &nbsp;&nbsp;&nbsp;&nbsp;Arc backward direction cost column (number)  
    **node_column**=*string*  
    &nbsp;&nbsp;&nbsp;&nbsp;Node cost column (number)  
    **method**=*string* **[required]**  
    &nbsp;&nbsp;&nbsp;&nbsp;Feature type  
    &nbsp;&nbsp;&nbsp;&nbsp;Allowed values: *bridge, articulation*  
    &nbsp;&nbsp;&nbsp;&nbsp;**bridge**: Finds bridges  
    &nbsp;&nbsp;&nbsp;&nbsp;**articulation**: Finds articulation points  
    **--overwrite**  
    &nbsp;&nbsp;&nbsp;&nbsp;Allow output files to overwrite existing files  
    **--help**  
    &nbsp;&nbsp;&nbsp;&nbsp;Print usage summary  
    **--verbose**  
    &nbsp;&nbsp;&nbsp;&nbsp;Verbose module output  
    **--quiet**  
    &nbsp;&nbsp;&nbsp;&nbsp;Quiet module output  
    **--qq**  
    &nbsp;&nbsp;&nbsp;&nbsp;Very quiet module output  
    **--ui**  
    &nbsp;&nbsp;&nbsp;&nbsp;Force launching GUI dialog

=== "Python (grass.tools)"

    **input** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Or data source for direct OGR access  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, vector, *name*  
    **output** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name for output vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: output, vector, *name*  
    **arc_layer** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Arc layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *1*  
    **node_layer** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Node layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *2*  
    **arc_column** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Arc forward/both direction(s) cost column (number)  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, dbcolumn, *name*  
    **arc_backward_column** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Arc backward direction cost column (number)  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, dbcolumn, *name*  
    **node_column** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Node cost column (number)  
    **method** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Feature type  
    &nbsp;&nbsp;&nbsp;&nbsp;Allowed values: *bridge, articulation*  
    &nbsp;&nbsp;&nbsp;&nbsp;**bridge**: Finds bridges  
    &nbsp;&nbsp;&nbsp;&nbsp;**articulation**: Finds articulation points  
    **overwrite** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Allow output files to overwrite existing files  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **verbose** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Verbose module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **quiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **superquiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Very quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  

    Returns:

    **result** : grass.tools.support.ToolResult | None  
    If the tool produces text as standard output, a *ToolResult* object will be returned. Otherwise, `None` will be returned.

    Raises:

    *grass.tools.ToolError*: When the tool ended with an error.

=== "Python (grass.script)"

    **input** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name of input vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Or data source for direct OGR access  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, vector, *name*  
    **output** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Name for output vector map  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: output, vector, *name*  
    **arc_layer** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Arc layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *1*  
    **node_layer** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Node layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, layer  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *2*  
    **arc_column** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Arc forward/both direction(s) cost column (number)  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, dbcolumn, *name*  
    **arc_backward_column** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Arc backward direction cost column (number)  
    &nbsp;&nbsp;&nbsp;&nbsp;Used as: input, dbcolumn, *name*  
    **node_column** : str, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Node cost column (number)  
    **method** : str, *required*  
    &nbsp;&nbsp;&nbsp;&nbsp;Feature type  
    &nbsp;&nbsp;&nbsp;&nbsp;Allowed values: *bridge, articulation*  
    &nbsp;&nbsp;&nbsp;&nbsp;**bridge**: Finds bridges  
    &nbsp;&nbsp;&nbsp;&nbsp;**articulation**: Finds articulation points  
    **overwrite** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Allow output files to overwrite existing files  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **verbose** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Verbose module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **quiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*  
    **superquiet** : bool, *optional*  
    &nbsp;&nbsp;&nbsp;&nbsp;Very quiet module output  
    &nbsp;&nbsp;&nbsp;&nbsp;Default: *None*

## DESCRIPTION

*v.net.bridge* finds bridges and articulation points in a network.

## NOTES

Bridge in a network is an edge/line whose removal would disconnect the
(sub-)network. A node is an articulation point if its removal would
disconnect the (sub-)network. For more information and formal
definitions check the wikipedia entries:
[bridge](https://en.wikipedia.org/wiki/Bridge_%28graph_theory%29) and
[articulation point](https://en.wikipedia.org/wiki/Cut_vertex).

The output of the module contains the selected features. For
**method=bridge**, lines corresponding to bridges are copied from the
input map to the output map. On the other hand, for
**method=articulation**, points are created on the positions of
articulation points.

In GRASS, *line* is not always a single line segment. It might be,
and often is, a sequence of line segments between two intersections.
Also, articulation point is a standard graph theoretic terminology which
is slightly misleading in GRASS. An articulation point in graph theory
is an articulation *node* in GRASS terminology.

## SEE ALSO

*[v.net](v.net.md), [v.category](v.category.md)*

## AUTHORS

Daniel Bundala, Google Summer of Code 2009, Student  
Wolf Bergenheim, Mentor

## SOURCE CODE

Available at: [v.net.bridge source code](https://github.com/OSGeo/grass/tree/main/vector/v.net.bridge)
([history](https://github.com/OSGeo/grass/commits/main/vector/v.net.bridge))  
Latest change: Friday Aug 08 09:39:19 2025 in commit [ed72c71](https://github.com/OSGeo/grass/commit/ed72c71d8580e872cd6fd345c84a15c324764465)
