HCA (Method 1)

Summary

HCA-MCA (Method 1) performs a High Consequence Area – Moderate Consequence Area (HCA-MCA) analysis workflow from start to finish per 49 CFR §192.903(1) and 84 FR 52180, using Class Location ranges output by the Class Location Calculation tool.

HCA-MCA (Method 1) is implemented as a ModelBuilder model tool, using the tools from the Prepare and Process toolsets in the Gas HCA Tool Python toolbox. It imports required source data into an existing Gas HCA Tool project geodatabase (created during the prerequisite Class Location analysis), performs data conditioning and intermediate calculations, and calculates final HCA ranges by method 1.

Usage

HCA-MCA (Method 1) implements G2-IS’ best practices for HCA analysis. However, because it is implemented as a ModelBuilder model tool, you are free to make a copy of the tool and modify it to suit your own needs.

HCA-MCA (Method 1) assumes that all feature classes and tables imported into the project geodatabase by, and/or created by, the Class Location analysis workflow are present in the project geodatabase and stored under their default names. The tool further assumes that you have utilized your identified sites as qualifying areas/buildings in your Class Location analysis. The tool only imports into your project geodatabase the additional data needed to complete the HCA method 1 analysis.

The following tools are used in HCA-MCA (Method 1). They are listed in their order of execution within the HCA-MCA (Method 1) tool; the heading for each section below is a hyperlink to the detailed help for the tool. Please note that, while the tools HCA-MCA (Method 1) uses are listed in order in which they are executed, the HCA-MCA (Method 1) tool parameters are shown in association with the tools that expose them, not necessarily in the order in which HCA-MCA (Method 1) lists them:

1) Prepare Pipe Segment and MAOP Features

Prepare Pipe Segment and MAOP Features copies your pipeline database pipe segment and Maximum Allowable Operating Pressure (MAOP) features (or records) to the PIPESEGMENT and MAOP tables, respectively in the project geodatabase.

  • Prepare Pipe Segment and MAOP Features copies your pipeline database pipe segment and Maximum Allowable Operating Pressure (MAOP) features (or records) to the PIPESEGMENT and MAOP tables, respectively, in the project geodatabase.
    • Input Pipe Segment Features or Records – This parameter allows you to specify the pipe features or records used to supply pipe characteristics to the HCA-MCA calculation. You may specify more than one data source, if desired. Typically, your input pipe segment features/records correspond to discrete lengths of pipe with common attributes stored on your pipeline centerlines. Your input pipe segment features/records must contain the attribution defined in the following dependent parameters (your field names need not match, but fields containing this information must be present):
      • Pipe Segment Centerline Identifier Field – This parameter allows you to specify the field in your input pipe features/records that uniquely identifies the centerline features on which the pipe segment features/records occur. Values for this field are copied to the ORIGINAL_ROUTE_ID field in the output PIPESEGMENT table and compared with ORIGNIAL_ROUTE_ID field in your project geodatabase CENTERLINE layer during processing.
      • Pipe Segment Begin Measure Field – This parameter allows you to specify the field in your input pipe features/records that represents the begin measure value of the pipe segment. Values for this field are copied to the FROM_MEASURE field in the output PIPESEGMENT table.
      • Pipe Segment End Measure Field – This parameter allows you to specify the field in your input pipe features/records that represents the end measure value of the pipe segment. Values for this field are copied to the TO_MEASURE field in the output PIPESEGMENT table.
      • Pipe Segment Nominal Diameter Field – This parameter allows you to specify the field in your input pipe features/records that represents the nominal diameter of the pipe segment in inches (for use in calculating the Potential Impact Radius). Values for this field are copied to the NOMINAL_DIAMETER field in the output PIPESEGMENT table.
  • Input MAOP Features or Records – This parameter allows you to specify the operating pressure features or records used to supply Maximum Allowable Operating Pressure (MAOP) values to the HCA-MCA calculation. You may specify more than one data source, if desired. Typically, your input MAOP features/records correspond to centerline segments with common MAOP values. Your input MAOP features/records must contain the attribution defined in the following dependent parameters (your field names need not match, but fields containing this information must be present):
    • MAOP Centerline Identifier Field – This parameter allows you to specify the field in your input MAOP features/records that uniquely identifies the centerline features on which the MAOP segment features/records occur. Values for this field are copied to the ORIGINAL_ROUTE_ID field in the output MAOP table and compared with ORIGNIAL_ROUTE_ID field in your project geodatabase CENTERLINE layer during processing.
    • MAOP Begin Measure Field – This parameter allows you to specify the field in your input MAOP features/records that represents the begin measure value of the MAOP segment. Values for this field are copied to the FROM_MEASURE field in the output MAOP table.
    • MAOP End Measure Field – This parameter allows you to specify the field in your input MAOP features/records that represents the end measure value of the MAOP segment. Values for this field are copied to the TO_MEASURE field in the output MAOP table.
    • MAOP Field – This parameter allows you to specify the field in your input MAOP features/records that represents the MAOP value (in psi) of the segment. Values for this field are copied to the ACTUAL_PRESSURE field in the output MAOP table.

2) Create Centerline PIR Buffers

Create Centerline PIR Buffers creates centerline Potential Impact Radius (PIR) segments on your centerline features, and then creates centerline PIR segment buffer polygons. The output features are stored in the following feature classes in the project geodatabase: HCA_PIR_SEGMENT and HCA_PIR_SEGMENT_BUFFER.

  • PIR Factor – This parameter allows you to specify the PIR combustion factor. The PIR combustion factor varies based on product type. The factor for ‘dry’ natural gas, which is 0.69, is the default value. The factor for ‘wet’ natural gas is 0.73.
  • Additional PIR Tolerance (Feet) – This parameter enables you to specify an additional tolerance (in feet) to add to the PIR, to account for uncertainty in the spatial location of your centerline, building intended for human occupancy (BIHO), and identified site features.

3) Create Structures and Site PIR Buffers

Create Structure and Site PIR Buffers creates PIR buffer polygons on your BIHO and identified site features and then generates centerline PIR BIHO and identified site segments by intersecting the buffer polygons for BIHOs and identified sites with your centerline features. The output features are stored in the following feature classes in the project geodatabase: HCA_STRUCTUREBUFFER and HCA_STRUCTURESEGMENT.

HCA-MCA (Method 1) exposes none of this tool’s parameters.

4) Prepare Roads

Prepare Roads buffers your input roads polyline features to the road width in preparation for Moderate Consequence Area (MCA) calculation, as defined in 84 FR 52180. The tool then buffers the road width polygons by the PIR and, finally, calculates road PIR buffer centerline intersection segments.

  • Input Road Features – This parameter allows you to specify a set of polyline road features to use in MCA determination. Road data sources and schemas vary widely. The tool assumes that you have already created an appropriate roads feature class or feature layer containing only designated interstates, other freeways or expressways, as well as any other principal arterial roadways with four or more lanes, as defined in the Federal Highway Administration’sHighway Functional Classification Concepts, Criteria and Procedures, Section 3.1. Your road features must contain one or more fields specifying road width information, which you select using the following dependent parameter:
    • Select Road Width Fields – This parameter allows you to select one or more numeric fields to be used to calculate road width (including shoulders). Click in the checkboxes next to your desired fields to select them. The values stored in your selected fields are summed to arrive at total road width.
  • Roads Width Units – This parameter allows you to specify the linear units for your road width attributes. Units can be either ‘Feet’ or ‘Meters.’
  • Road Width Divisible Factor – This parameter allows you specify a value by which to divide the totaled road width. Your road width attributes likely define the actual road width. When buffering the road polyline features to create road polygons, a value of half the road width is generally used since the buffer operation buffers both sides of your road features. This parameter defines the value by which the sum of your road attributes is divided to arrive at a proper buffer radius width. The default value is 2 and need not be modified in most instances.
  • Road Width Tolerance – This parameter allows you to specify an additional road width spatial tolerance to be added to be to the road width buffer distance to account for uncertainty in the spatial position of your road and/or centerline features. Specify this value in your selected road width units.

5) HCA-MCA Calculation (Method 1)

HCA-MCA Calculation (Method 1) performs the final step in the analysis workflow, calculating your HCA ranges by method 1. This tool also produces dynamically segmented HCA segments that retain much useful attributes from the analysis process. The output features are stored in the following feature classes in the project geodatabase: HCA_RANGE_M1 and HCA_SEGMENT_COUNT_M1.

  • Class Type – This parameter allows you to specify whether to use clustered or unclustered Class Location values for HCA determination. When set to ‘Class Clustered,’ the tool uses ‘clustered’ Class Location features in the calculation. When set to ‘Class Unclustered,’ the tool uses unclustered Class Location features in the calculation.
  • Boundary Extension Method – This parameter allows you to specify how to calculate extensions for HCA-MCA ranges not due to Class 3 or Class 4 location units. When you select ‘Arc Method,’ HCA-MCA ranges not determined by Class 3 or Class 4 location units are extended by the radius length of the PIR from the end of the HCA-MCA range, executed as the point at which a PIR circle centered on the end of the non-extended HCA-MCA range intersects the centerline, as illustrated in 49 CFR §192 Appendix E.(I.) Figure A. The arc method is strongly recommended. When you select ‘Perpendicular/Parallel Method,’ HCA-MCA ranges not determined by Class 3 or Class 4 location units are extended along the path of the pipeline centerline by the length of the PIR.
  • Create Relationship Tables – This checkbox parameter allows you to specify whether to create a series of many-to-many (M:N) relationship tables detailing the relationships of individual structures/qualifying areas/identified sites to individual HCA-MCA segments and associated buffer features. The relationship tables are very useful in performing QA/QC of tool results. However, because these are M:N relationships, these tables can become very Check the checkbox to enable creation of the relationship tables. Use this parameter with caution.

Syntax

HCAMCAMethod1 (Input_Project_Database, Input_PipeSegment_Features_or_Records, Pipe_Segment_Centerline_Identifier_Field, Pipe_Segment_Begin_Measure_Field, Pipe_Segment_End_Measure_Field, Nominal_Diameter_Field, Input_MAOP_Features_or_Records, MAOP_Centerline_Identifier_Field, MAOP_Begin_Measure_Field, MAOP_End_Measure_Field, MAOP_Field, PIR_Factor, {Additional_PIR_Tolerance__Feet_}, Input_Road_Features, Select_Road_Width_Fields, Roads_Width_Units, Road_Width_Divisible_Factor, {Road_Width_Tolerance}, Class_Type, Boundary_Extension_Method, {Create_Relationship_Tables})

Parameter Explanation Data Type
Input_Project_Database Dialog Reference

Select the Gas HCA Tool project geodatabase you created while performing the prerequisite Class Location analysis. The output from this tool is stored in this workspace by default.

There is no Python reference for this parameter.

Workspace
Input_Pipe_Segment_Features_or_Records Dialog Reference

Specify your input pipe segment features/records.

There is no Python reference for this parameter.

Multiple Value
Pipe_Segment_Centerline_Identifier_Field, Dialog Reference

Specify the field that uniquely identifies the centerline segment on which the pipe segment feature/record occurs.

There is no Python reference for this parameter.

Field
Pipe_Segment_Begin_Measure_Field Dialog Reference

Specify the field containing the begin measure value of the pipe segment feature/record on the underlying centerline feature.

There is no Python reference for this parameter.

Field
Pipe_Segment_End_Measure_Field Dialog Reference

Specify the field containing the end measure value of the pipe segment feature/record on the underlying centerline feature.

There is no Python reference for this parameter.

Field
Pipe_Segment_Nominal_Diameter_Field Dialog Reference

Specify the field that stores the outside diameter (in inches) of the pipe segment feature/record.

There is no Python reference for this parameter.

Field
Input_MAOP_Features_or_Records Dialog Reference

Specify your input MAOP features/records.

There is no Python reference for this parameter.

Table View
MAOP_Centerline_Identifier_Field, Dialog Reference

Specify the field that uniquely identifies the centerline segment on which the MAOP feature/record occurs.

There is no Python reference for this parameter.

Field
MAOP_Begin_Measure_Field Dialog Reference

Specify the field containing the begin measure value of the MAOP feature/record on the underlying centerline feature.

There is no Python reference for this parameter.

Field
MAOP_End_Measure_Field Dialog Reference

Specify the field containing the end measure value of the MAOP feature/record on the underlying centerline feature.

There is no Python reference for this parameter.

Field
MAOP_Field Dialog Reference

Specify the field that stores the MAOP value (in PSI) of the MAOP feature/record.

There is no Python reference for this parameter.

Field
PIR_Factor Dialog Reference

Enter the PIR combustion factor for the PIR calculation. 0.69, the factor for ‘dry’ natural gas, is the default value.

There is no Python reference for this parameter.

Double
 

Additional_Tolerance_for_PIR__Feet_

(Optional)

Dialog Reference

Enter an additional tolerance (in feet) to add to the PIR, if desired. The default value is 0 feet.

There is no Python reference for this parameter.

Double
Input_Road_Features Dialog Reference

Specify your input road features.

There is no Python reference for this parameter.

Feature Layer
Select_Road_Width_Fields Dialog Reference

Select your input road width field(s).

There is no Python reference for this parameter.

Multiple Value
Roads_Width_Units Dialog Reference

Select the desired road width linear units of measure. The default is ‘Feet.’

There is no Python reference for this parameter.

String
Road_Width_Divisible_Factor Dialog Reference

Specify the value by which to divide the sum of the road width field values. The default value is 2.

There is no Python reference for this parameter.

Long
 

Road_Width_Tolerance

(Optional)

Dialog Reference

Specify an additional road width tolerance value, if desired

There is no Python reference for this parameter.

Double
Class_Type Dialog Reference

Specify the desired class output calculation. The available options are ‘ Class Clustered’ and ‘Class Unclustered’.

There is no Python reference for this parameter.

Field
Boundary_Extension_Method Dialog Reference

Specify the method used to extend HCA-MCA ranges not defined by Class 3 or Class 4 location units.

There is no Python reference for this parameter.

String
Create_Relationship_Tables Dialog Reference

Specify the method used to extend HCA-MCA ranges not defined by Class 3 or Class 4 location units.

There is no Python reference for this parameter.

Boolean

Code sample

The following script demonstrates how to use HCA-MCA (Method 1) with file geodatabase data:

# Import the Gas HCA Python library
import hcapy
# Import the Gas HCA Master Tools toolbox
arcpy.ImportToolbox(“C:\Python27\ArcGIS10.6\Lib\site-packages\hcapy\esri\Toolboxes\Gas HCA Master Tools (Pro).tbx”)
# Specify tool parameters
Input_Project_Database = r”C:\projects\GasHCA_Enhancements\A_DOTCLass_Test6.gdb”
Input_PipeSegment_Features = r”C:\projects\GasHCA_Enhancements\Test.gdb\PipeSegment”
Pipe_Segment_Centerline_ID_Field = “RouteEventID”
Pipe_Segment_Begin_Measure_Field = “BEGIN_MEASURE”
Pipe_Segment_End_Measure_Field = “END_MEASURE”
Nominal_Diameter_Field = “Outsidediameter”
Input_MAOP_Features = r”C:\projects\GasHCA_Enhancements\Test.gdb\MAOP”
MAOP_Centerline_ID_Field = “RouteEventID”
MAOP_Begin_Measure_Field = “BEGIN_MEASURE”
MAOP_End_Measure_Field = “END_MEASURE”
MAOP_Field = “ActualPressure”
PIR_Factor = 0.69
Additional_PIR_Tolerance = 0
Input_Road_Features = r”C:\projects\GasHCA_Enhancements\Test.gdb\Roads”
Road_Width_Fields = [“Road_Width”]
Roads_Width_Units = ‘Feet’
Road_Width_Divisible_Factor = 2
Class_Type = “Clustered”
Boundary_Extension_Method = “Arc Method”
Build_Relationship_Tables = False
# Execute the tool
HCAMethod1 (Input_Project_Database, Input_PipeSegment_Features, Pipe_Segment_Centerline_ID_Field, Pipe_Segment_Begin_Measure_Field, Pipe_Segment_End_Measure_Field, Nominal_Diameter_Field, Input_MAOP_Features, MAOP_Centerline_ID_Field, MAOP_Begin_Measure_Field, MAOP_End_Measure_Field, MAOP_Field, PIR_Factor, Additional_PIR_Tolerance, Input_Road_Features, Road_Width_Fields, Roads_Width_Units, Road_Width_Divisible_Factor, Class_Type, Boundary_Extension_Method, Build_Relationship_Tables)

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.

Related topics

Tags

High Consequence Area, HCA, Moderate Consequence Area, MCA, centerline, pipe segment, diameter, maximum allowable operating pressure, MAOP, potential impact radius, PIR, class location, clustered, unclustered.

Credits

Copyright © 2016-2021 by G2 Integrated Solutions, LLC. All Rights Reserved.

Use limitations

None.