Bridge Blockage Data Fields
A blockage models a time-varying obstruction with user-defined contraction and expansion loss coefficients.
Bridge blockage data can be edited on either the Bridge Blockage Grid View of the Links Grid or the Bridge Blockage Property Sheet, or by clicking on the 
button adjacent to the Inlet blockage ID or Outlet blockage ID fields in the Bridge Opening property sheet, and selecting Open from the context menu.
To view and edit all blockage data, use the Property Sheet.
The following table describes all the blockage specific data which can be used to define a blockage associated with a bridge opening. For details of results fields, see the Link Results Data Fields topic.
Common Data Fields Fields that are common to the majority of objects can be found in the Common Fields topic.
Bridge Blockage Data
Database Table Name: hw_bridge_blockage
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Show Columns |
Database Names |
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Size, Type and Units |
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Defaults and Error Limits |
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Field Name |
Help Text |
Database Field |
Size |
Precision |
Default |
Error Lower Limit |
Error Upper Limit |
Warning Lower Limit |
Warning Upper Limit |
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| ID |
Identity of the blockage. |
id | Text | 64 | |||||||
| Bridge US node ID |
Identity of the upstream node for the bridge that this blockage is associated with. 
Note
The bridge must have an opening associated with it. |
bridge_us_node_id | Text | 64 | |||||||
| Link suffix |
Link suffix of the bridge to which the blockage is associated. |
bridge_link_suffix | Text | 1 | |||||||
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Asset ID |
For reference only. Designed as a reference to an asset database, but could be used for anything. |
asset_id |
Text |
64 |
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3 |
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0 |
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System Type |
Choose the system type from the dropdown list. See System Type for more information. |
system_type |
Text |
10 |
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0 |
Other |
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| Initial blockage | The initial blockage proportion can be set to between 0.0 (no blockage - free flow) and 1.0 (fully blocked - no flow). | blockage_proportion | Double | 3 | 0 | 0 | 1 | ||||
| Inlet Loss Coefficient | The inlet loss coefficient must be greater or equal to 0.0. Default is 1.5. | Inlet_loss_coefficient | Double | 3 | 1.5 | 0 | |||||
| Outlet loss coefficient | The outlet loss coefficient greater or equal to 0.0. Default is 1.0. | Outlet_loss_coefficient | Double | 3 | 1.0 | 0 | |||||
| Positive blocking rate |
The rate at which the proportion of the blockage goes from one state to another in a positive direction. The value must be greater than zero. |
positive_prop_change | Double | RS | 5 | 0.1 | 0.000001 | ||||
| Negative blocking rate |
The rate at which the proportion of the blockage goes from one state to another in a negative direction. The value must be greater than zero. |
negative_prop_change | Double | RS | 5 | 0.1 | 0.000001 | ||||
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Threshold |
The minimum blockage proportion step which the software will implement. Any changes below this threshold will be ignored. This prevents oscillation. |
threshold |
Double |
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5 |
0 |
0 |
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