GENERATE COULD AFFECT SEGMENTS

Summary

Generate Could Affect Segments calculates “could affect” segment ranges on your centerline route features based on information stored in your Liquids HCA project geodatabase’s HCA intersections table and stores the output in a could affect segments table in your Liquids HCA project geodatabase.

To learn more about the Liquids HCA Tool in general, please see Liquids HCA Tool Frequently Asked Questions.

To learn more about the structure of the Liquids HCA Tool project geodatabase, please see Liquids HCA Tool Data Dictionary.

Usage

From a regulatory reporting standpoint, the definition of could affect segments is simple. Any release point plume that affects any High Consequence Area (HCA) in any way results in a could affect segment subject to the pipeline integrity management requirements of 49 CFR §195.452. However, operators are also required to gauge risk in prioritizing pipeline integrity management activities. An important aspect of evaluating pipeline risk is evaluating Consequence of Failure (CoF). For hazardous liquids pipelines, CoF varies based on product type, HCA type, intersection type, and, to some extent, the area affected, and the volume of product introduced into a given HCA, and also the timing of the release plume’s entry into a given HCA relative to the start time of the release. All of this information is stored in the HCA intersections table of your Liquids HCA project geodatabase.

Generate Could Affect Segments enables you to calculate different types of could affect segments based on different combinations of HCA types/groups and HCA intersection methods. HCA types and groupings are stored in a lookup table (HCA_GROUP_LOOKUP) in your Liquids HCA project geodatabase, as are HCA intersection types and groupings (stored in the HCA_INTERSECTIONS_METHOD_LOOKUP table). Could affect segment types are based on a combination of HCA type and/or groupings and intersection method groupings; these could affect segment type definitions are stored in a could affect segment definitions lookup table (HCA_CA_SEGMENTS_DEF). The HCA types/groupings, intersection method groupings, and could affect segment definitions lookup tables are all instantiated and populated by the Initialize Database tool. (You may extend the could affect segment definitions lookup table as needed to accommodate new could affect segment type definitions.) The Generate Could Affect Segments tool allows you to select all could affect segment type definitions at runtime, or interactively define alternate could affect segment types, and then generates could affect segments for all specified could affect segment types.

Could affect determinations are actually made based on individual release points (i.e., based on whether the plume for a given release point affects an HCA). To construct a could affect segment, a run of contiguously adjacent could affect release points is strung together to create a could affect segment. The tool allows you to adjust the extent to which could affect segments are extended relative to their bounding non-could affect release points.

The Generate Could Affect Segments tool uses the following parameters:

Input Project Database – This parameter allows you to specify your Liquids HCA project file geodatabase. You created your project geodatabase with the Initialize Database tool. By default, your input release point features, centerline route features, HCA intersections table, intersection methods lookup table, HCA groupings lookup table, and HCA could affect type definitions lookup table are all sourced from your Liquids HCA Project file geodatabase, and the output could affect segments records are written to your project file geodatabase.
Input Centerline Route Features – This parameter allows you to specify the centerline route features that underly your input release point features. You import centerline route features into your Liquids HCA project geodatabase using the Initialize Database tool. The default value for this parameter is the ROUTES feature class in your Liquids HCA project geodatabase. The tool looks for this feature class automatically; there is generally no need to alter the default parameter value. Note that the input route features must include properly populated ROUTE_ID, FROM_MEAS, and TO_MEAS columns.
Input Release Point Features – This parameter allows you to specify the release point features that are the starting points for the modeled release plumes. You create release point features using the Create Release Points tool. The default value for this parameter is the OSPOINTM feature class in your Liquids HCA project geodatabase. The tool looks for this feature class automatically; there is generally no need to alter the default parameter value.
Input HCA Intersections Table – This parameter allows you to specify your input HCA intersections table, which stores information about intersections of HCAs by your release plumes. You create the HCA intersections table using the Calculate Land Spill HCA Intersections and Calculate Hydro Trace HCA Intersections tools. The default value for this parameter is the ROUTES feature class in your Liquids HCA project geodatabase. The tool looks for this feature class automatically; there is generally no need to alter the default parameter value.
Input HCA Intersection Methods Lookup Table – This parameter allows you to specify your input HCA intersection methods lookup table. This table stores the different ways by which a release plume may intersect an HCA (e.g., direct centerline intersection, overland flow intersection, hydrographic transport intersection, radial slick spread intersection) and combinations of these intersection types. You instantiate and populate this lookup table by running the Initialize Database tool. The default value for this parameter is the HCA_INTERSECTIONS_METHOD_LOOKUP table in your Liquids HCA project geodatabase. The tool looks for this table automatically; there is generally no need to alter the default parameter value.
Input HCA Group Lookup Table – This parameter allows you to specify your input HCA types and groupings lookup table. This table stores the different types of HCAs (HPA, OPA, EC, DW, and NW) and combinations of these HCA types. You instantiate and populate this lookup table by running the Initialize Database tool. The default value for this parameter is the HCA_GROUP_LOOKUP table in your Liquids HCA project geodatabase. The tool looks for this table automatically; there is generally no need to alter the default parameter value.
Input “Could Affect” Segment Definitions Table – This parameter allows you to specify your input could affect segment definitions lookup table. The table defines could affect segment types based on the combination of an HCA type or grouping and an intersection method(s) grouping. You instantiate and populate this lookup table by running the Initialize Database tool. The default value for this parameter is the HCA_CA_SEGMENTS_DEF table in your Liquids HCA project geodatabase. The tool looks for this table automatically; there is generally no need to alter the default parameter value.
Use All HCA “Could Affect” Segment Definitions – This checkbox parameter allows you to specify whether to use all could affect segment type definitions in the could affect segment definitions lookup table when constructing output could affect segments. If enabled, the tool generates all defined types of could affect segments. This parameter is enabled by default. If you disable this parameter, you may specify your own could affect segment definitions using the parameters in the HCA “Could Affect” Definitions parameter group, which are exposed when this parameter is disabled.
HCA “Could Affect” Definitions – This value table parameter is visible and enabled only when the Use All HCA “Could Affect” Segment Definitions parameter is disabled. It allows you to interactively define your own could affect segment definitions, based on combinations of intersections methods and HCA groupings.
- HCA Intersection Method – This value table column allows you to select a plume-HCA intersection method. The available choices are derived from the HCA intersection types and groupings lookup table (HCA_INTERSECTIONS_METHOD_LOOKUP) in your Liquids HCA project geodatabase.
- HCA Group – This value table column allows you to select an HCA type or grouping. The available choices are derived from the HCA types and groupings lookup table (HCA_GROUP_LOOKUP) in your Liquids HCA project geodatabase.

You may define as many could affect segment types, based on combinations of HCA intersection method and HCA group, as you like.

Percentage to Extend Beginnings of “Could Affect” Segments – This parameter allows you to define the extent to which could affect segments are extended at the beginning of the segment based on the distance from the first could affect release point in the could affect segment relative to the preceding non-could affect release point located immediately before the start of the segment. The default value of 100% causes the could affect segment to be extended all the way to the preceding non-could affect release point that bounds the start of the segment; a value of 0% percent causes no extension beyond the first could affect release point defining the start of the could affect segment.
Percentage to Extend Ends of “Could Affect” Segments – This parameter allows you to define the extent to which could affect segments are extended at the end of the segment based on the distance from the last could affect release point in the could affect segment relative to the following non-could affect release point located immediately after the end of the segment. The default value of 100% causes the could affect segment to be extended all the way to the following non-could affect release point that bounds the end of the segment; a value of 0% percent causes no extension beyond the last could affect release point defining the end of the could affect segment.
Output “Could Affect” Segment Table – This parameter allows you to specify the output HCA intersections table. The default destination is the HCA_CA_SEGMENTS table in your specified Liquids HCA project geodatabase. If the table already exists, the tool appends output to the table. If not, the tool will create the table. There is generally no need to alter the default parameter value.

In a typical Liquids HCA Tool analysis workflow, Generate Could Affect Segments is run after the Calculate Land Spill HCA Intersections and Calculate Hydro Trace HCA Intersections tools and before Generate Could Affect Segments Report.

For visual reference on Liquids HCA Tool execution order, see Liquids HCA Tool Process Flow Diagrams.

Syntax

GenerateCouldAffectSegments_ (in_workspace, in_route_features, in_ospointm_features, in_hca_intersect_table, in_int_method_lookup_table, in_hca_group_lookup_table, in_hca_ca_segments_def_table, {in_all_queries}, {in_pre_queries}, {in_extend_begin_segment}, {in_extend_end_segment}, out_hca_ca_segments_table)

Parameter	Explanation	Data Type
in_workspace	Dialog Reference Specify your input Liquids HCA Tool project geodatabase. The output from this tool is stored in this workspace. There is no Python reference for this parameter.	Workspace or Feature Dataset
in_route_features	Dialog Reference Specify your input pipeline centerline route features. There is no Python reference for this parameter.	Feature Layer
in_ospointm_features	Dialog Reference Specify your input release points features. There is no Python reference for this parameter.	Feature Layer
in_hca_intersect_table	Dialog Reference Specify your input HCA intersections table. There is no Python reference for this parameter.	Table View
in_int_method_lookup_table	Dialog Reference Specify your input HCA intersection methods lookup Table. There is no Python reference for this parameter.	Table View
in_hca_group_lookup_table	Dialog Reference Specify your input HCA types and groups lookup table. There is no Python reference for this parameter.	Table View
in_hca_ca_segments_def_table	Dialog Reference Specify your input could affect segment definitions lookup table. There is no Python reference for this parameter.	Table View
in_all_queries (Optional)	Dialog Reference Check the checkbox to use all could affect segment definitions in your input could affect segment definitions lookup table. Uncheck the checkbox to interactively enter your own could affect segment definitions. There is no Python reference for this parameter.	Boolean
in_pre_queries (Optional)	Dialog Reference Specify combinations of HCA intersection methods and HCA types/groups to define your could affect segment definitions. There is no Python reference for this parameter.	Value Table
in_extend_begin_segment (Optional)	Dialog Reference Specify the percentage distance between the first could affect release point in the could affect segment and the preceding non-could affect release point by which to extend the beginning of the could affect segment. There is no Python reference for this parameter.	Long
in_extend_end_segment (Optional)	Dialog Reference Specify the percentage distance between the last could affect release point in the could affect segment and the following non-could affect release point by which to extend the end of the could affect segment. There is no Python reference for this parameter.	Long
out_hca_ca_segments_table	Dialog Reference Specify your output could affect segments table. There is no Python reference for this parameter.	Table

Code sample

The following example demonstrates how to use Generate Could Affect Segments in Python scripting:

import arcpy

arcpy.ImportToolbox(r”C:\Program Files\ArcGIS\Pro\bin\Python\envs\arcgispro-py3\Lib\site-packages\liquidshca\esri\toolboxes\LiquidsHCA.pyt”)

arcpy.env.workspace = r”C:\data\test.gdb”

in_workspace = r “C:\data\test.gdb”

release_points = r “C:\data\test.gdb\OSPointM”

route_features = r “C:\data\test.gdb\Routes”

hca_intersections = r “C:\data\test.gdb\HCA_Intersections”

int_method_tbl = r “C:\data\test.gdb\Intersections_Method_Lookup”

hca_group_tbl = r “C:\data\test.gdb\HCA_Group_Lookup”

hca_seg_def_tbl = r “C:\data\test.gdb\HCA_CA_Segments_Def”

hca_ca_seg_tbl = r “C:\data\test.gdb\HCA_CA_Segments”

all_hca_combinations = True

could_affec_queries = “”

extend_begining = 100

extend_ending = 100

arcpy.liquidshca.GenerateCouldAffectSegments(in_workspace, route_features, release_points, hca_intersections, int_method_tbl, hca_group_tbl, hca_seg_def_tbl, could_affec_queries, all_hca_combinations, extend_begining, extend_ending, hca_ca_seg_tbl)

Environments

Current Workspace, Scratch Workspace, Qualified Field Names, OutputCONFIG Keyword, Auto Commit

Licensing information

This tool requires a valid Liquids HCA Tool user license or subscription. Please see the Request License and Register License tool help topics for details on obtaining and registering a Liquids HCA Tool software license.

Credits

Use limitations

There are no access and use limitations for this item.