HCA CALCULATION (METHOD 1 – EXTERNAL CLASS LOCATION DATA)

HCA Calculation (Method 1 - External Class Location Data)

Summary

HCA Calculation (Method 1 – External Class Location Data) determines High Consequence Area (HCA) ranges by method 1 (per 49 CFR §192.903(1)) using Class Location data imported into your Gas HCA Tool project geodatabase from an external source (e.g., from your pipeline database). The tool designates as an HCA all centerline ranges meeting any of the following criteria:

(i) A Class 3 location under §192.5; or

(ii) A Class 4 location under §192.5; or

(iii) Any area in a Class 1 or Class 2 location where the potential impact radius is greater than 660 feet (200 meters), and the area within a potential impact circle contains 20 or more buildings intended for human occupancy; or

(iv) Any area in a Class 1 or Class 2 location where the potential impact circle contains an identified site.

Usage

Input Class Location Features – This tool uses as input your own Class Location features (or records) from your pipeline database and imports them into the Gas HCA Tool project geodatabase. However, your input Class Location features/records must contain the following attributes in order for the tool to run:
- - Centerline Identifier Field – A field that uniquely identifies the centerline feature on which each input Class Location feature/record occurs. This field will be mapped to and compared with ORIGINAL_ROUTE_ID field in the centerline features stored in the Gas HCA Tool project geodatabase (in the CENTERLINE feature class, by default).
  - Begin Measure Field – A field that defines the begin measure values of your Class Location features/records.
  - End Measure Field – A field that defines the end measure values of your Class Location features/records.
  - Class Location Field – A field that contains the class location values for your Class Location features/records.
Input Structure and Site Segment Features – This tool uses as input the Building Intended for Human Occupancy (BIHO) and identified site segments created by the Create Structure and Site PIR Buffers tool. Unless otherwise specified, the tool defaults this parameter to the HCA_STRUCTURESEGMENT feature class in your selected Gas HCA Tool project geodatabase.
Output HCA Range Features – This parameter defines the destination of the output HCA range features. Unless otherwise specified, the default destination for the output HCA range features is the HCA_RANGE_M1 feature class in your selected Gas HCA Tool project geodatabase.
Output HCA Segment Features – This parameter defines the destination of the output dynamically segmented HCA range features, which contain useful information, such as BIHO and identified site counts, and the provenance of the segment. Unless otherwise specified, the default destination for the output HCA segment features is the HCA_SEGMENT_COUNT_M1 feature class in your selected Gas HCA Tool project geodatabase.
In a typical method 1 HCA analysis workflow, HCA Calculation (Method 1 – External Class Location Data) follows Create Structure and Site PIR Buffers and is the final process step in the workflow.

Syntax

HCAMethod1B_ (project_database, dotclass_table, route_id, begin_measure, end_measure, class_field, {hca_range}, {hca_segment_count_out})

Parameter	Explanation	Data Type
project_database	Dialog Reference Select a Gas HCA Tool project geodatabase created using the Initialize Database tool. The output from this tool is stored in this workspace. There is no Python reference for this parameter.	Workspace
dotclass_table	Dialog Reference Specify your input Class Location features or records. There is no Python reference for this parameter.	Table View
route_id	Dialog Reference Specify the field that uniquely identifies the centerline feature on which each input Class Location feature/record occurs. There is no Python reference for this parameter.	Field
begin_measure	Dialog Reference Specify the field that defines the begin measure values of your Class Location features/records. There is no Python reference for this parameter.	Field
end_measure	Dialog Reference Specify the field that defines the end measure values of your Class Location features/records. There is no Python reference for this parameter.	Field
class_field	Dialog Reference Specify the field that contains the class location values for your Class Location features/records. There is no Python reference for this parameter.	Field
hca_range (Optional)	Dialog Reference Specify the destination of the output HCA range features. There is no Python reference for this parameter.	Feature Layer
hca_segment_count_out (Optional)	Dialog Reference Specify the destination of the output HCA segment features. There is no Python reference for this parameter.	Feature Layer

Code Sample

HCA Calculation (Method 1 – External Class Location Data)

# Import GasHCA Library

import hcapy

# improt Gas HCA Tools

arcpy.ImportToolbox(“C:\Python27\ArcGIS10.6\Lib\site-packages\hcapy\esri\Toolboxes\Gas HCA Tools.pyt”)

project_database = r”C:\projects\GasHCA_Enhancements\A_DOTCLass_Test5.gdb”

dotclass_table = r”C:\projects\GasHCA_Enhancements\Test.gdb\Dot_Class”

route_id = “RouteEventID”

begin_measure = “BEGIN_MEASURE”

end_measure = “END_MEASURE”

class_field = “Class”

# Execute tool

arcpy.HCAMethod1B_hcapy(project_database, dotclass_table, route_id, begin_measure, end_measure, class_field)

Environments

Current Workspace, Scratch Workspace, Default Output Z Value, M Resolution, M Tolerance, Output M Domain, Output XY Domain, Output Z Domain, Output Coordinate System, Extent, Geographic Transformations, Output has M values, Output has Z values, XY Resolution, XY Tolerance, Z Resolution, Z Tolerance

Licensing information

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

Credits

Use limitations

HCA Calculation (Method 1 – External Class Location Data) does not currently include calculation of Moderate Consequence Area (MCA) ranges. You may use the Esri Overlay Route Events tool to overlay method 1 and method 2 results, and thereby update method 1 HCA results with MCA ranges identified with the HCA Calculation (Method 2) tool.