Calculate Bridge Offsets (Topographic Production)

Summary

Calculates the offsets necessary to properly display bridges at a given location.

Offsets can be calculated for either line or point bridge features. For a line bridge feature, an offset will be calculated for the width of a bridge based on the overpassing feature that runs through the bridge. For point bridges, offsets include the following:

• The rotation angle of a bridge based on its overpassing feature
• The position of the bridge if the original position is not coincident with the overpassing feature

Usage

• This tool is meant to be used on topographic map data and requires a well-defined symbology for point and line bridges. This tool can also be used on culverts meeting the same criteria as bridges.

• This tool should not be confused with the Create Overpass tool in the Cartography toolbox. The Create Overpass tool generates new bridge features at the intersection of other features; the Calculate Bridge Offsets tool symbolizes existing features.

• The feature layer that contains the bridge features must have attribute-driven symbology enabled.

• When a point feature class is used for Input Bridge Features, the following double fields are added:

  • CBO_OffsetX—Apply the offset along the x-axis.
  • CBO_OffsetY—Apply the offset along the y-axis.
  • CBO_Rotation—Apply the rotation of the feature symbology.

• When a line feature class is used for Input Bridge Features, the following double field is added:

  • CBO_Offset—Apply the offset to line features.

Parameters

Dialog

Label	Explanation	Data Type
Input Bridge Features	The feature layer that contains bridge features for which symbol offsets will be updated. Symbolize the bridge features layer with proper bridge features and enable attribute-driven symbology on it.	Layer
Overpassing Features	The feature layer that contains the features overpassing the bridges.	Layer
Reference Scale	The scale at which symbols appear at their intended size.	Long
Search Distance (Optional)	The distance, calculated in map units, by which this tool will buffer point bridge features when identifying the overpassing features. This parameter is only available for point bridges. The default is 0 meters.	Linear Unit
Expand to Markers (Optional)	Specifies whether marker layers on overpassing symbols will be included when analyzing widths. Checked—Marker layers on overpassing symbols will be included when analyzing widths. Unchecked—Marker layers on overpassing symbols will not be included. This is the default.	Boolean
Additional Offset (Optional)	An offset added to the bridge width. The default is 0 points.	Linear Unit
Minimum Length (Optional)	The minimum length of a line bridge. The default is 1.35 millimeters. If the length of the bridge is less than the minimum length, it will be expanded to minimum length.	Linear Unit
Bridge Features Subtype (Optional)	The subtype of the feature class from the Input Bridge Features parameter that will be modified by this operation.	String
Overpassing Features Subtype (Optional)	The subtype of the feature class in the Overpassing Features parameter that will be used in this operation.	String

Derived Output

Label	Explanation	Data Type
Updated Bridge Features	Bridge features that have been offset based on in_overpassing_features.	Layer

Python

arcpy.topographic.CalculateBridgeOffsets(in_bridge_features, in_overpassing_features, reference_scale, {search_distance}, {expand}, {offset}, {min_length}, {bridge_subtype}, {overpassing_subtype})

Name	Explanation	Data Type
in_bridge_features	The feature layer that contains bridge features for which symbol offsets will be updated. Symbolize the bridge features layer with proper bridge features and enable attribute-driven symbology on it.	Layer
in_overpassing_features	The feature layer that contains the features overpassing the bridges.	Layer
reference_scale	The scale at which symbols appear at their intended size.	Long
search_distance (Optional)	The distance, calculated in map units, by which this tool will buffer point bridge features when identifying the overpassing features. This parameter is only available for point bridges. The default is 0 meters.	Linear Unit
expand (Optional)	Specifies whether marker layers on overpassing symbols will be included when analyzing widths. EXPAND—Marker layers on overpassing symbols will be included when analyzing widths. NO_EXPAND—Marker layers on overpassing symbols will not be included. This is the default.	Boolean
offset (Optional)	An offset added to the bridge width. The default is 0 points.	Linear Unit
min_length (Optional)	The minimum length of a line bridge. The default is 1.35 millimeters. If the length of the bridge is less than the minimum length, it will be expanded to minimum length.	Linear Unit
bridge_subtype (Optional)	The subtype of the feature class from the in_bridge_features parameter that will be modified by this operation.	String
overpassing_subtype (Optional)	The subtype of the feature class in the in_overpassing_features parameter that will be used in this operation.	String

Derived Output

Name	Explanation	Data Type
updated_bridge_features	Bridge features that have been offset based on in_overpassing_features.	Layer

Code sample

CalculateBridgeOffsets example (stand-alone script)

The following code sample calculates the offsets to display bridges properly at a location.

# Name: CalculateBridgeOffsets_sample.py
# Description: Calculates the offsets to display bridges properly at a location

# Import System Modules
import arcpy
from arcpy import env

# Check Out Extensions
arcpy.CheckOutExtension('Foundation')

# Set the Cartographic Environment
env.cartographicCoordinateSystem = 'GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]]'
env.referenceScale = 10000

# Setting Local Variables
in_bridge_features = r'C:\Data\Layers\BridgeL.lyrx'
in_overpassing_features = r'C:\Data\Layers\RoadL.lyrx'
reference_scale = 1000

# Execute Calculate Bridge Offsets
arcpy.topographic.CalculateBridgeOffsets(in_bridge_features,in_overpassing_features,reference_scale)

# Check In Extensions
arcpy.CheckInExtension('Foundation')

Environments

This tool does not use any geoprocessing environments.

Licensing information

• Basic: No
• Standard: Requires Production Mapping
• Advanced: Requires Production Mapping