In Autodesk Civil 3D, junction structures have built-in resize behaviours that control how far you can move the rim, connected pipes and sump up and down.
For example, if you move the top-most pipe invert up, raising its level to the point where it reaches the top of the structure (cover), the cover moves up automatically. This is to ensure that the pipe remains connected to the structure below the vertical pipe clearance area. The resize behaviour allows the junction structure to maintain the frame height, cone height and honour the vertical pipe clearance area, at the top of the structure, with no pipes connecting in to that part of the structure.
If you try to move a connected pipe into the structure’s vertical pipe clearance area, you will notice in your drawing that the top of the structure (cover) automatically moves up.
This is just one example of the resize behaviour that is built in to junction structures. Other resize behaviours control how far you can move the junction structure’s cover or sump up and down.
Before editing junction structures, make sure you understand the following about the resize behaviour:
- Level changes to the junction structure’s cover, connected pipes, or sump, could occur when the structure is grip edited, or when the referenced surface changes, or when pipe levels are changed.
- The resize behaviour of junction structures is independent of the behaviour supplied by part rules. However, part rules can be configured so that they affect the structure resize behaviour.
- Note that the resize behaviours explained here apply only to junction structures. They do not apply to inlet/outlet structures or null structure types.
- To verify that a structure is categorized as a junction structure, check that the Part_Type property is set to Struct_Junction. This is displayed on the Part Properties tab of the Structure Properties dialog box, in the Part Data section.
Moving Junction Structures That Are Connected To Pipes
This section describes the structure resize behaviour that is invoked in the following situations:
- moving the top of a junction structure (cover) up or down
- moving a pipe that is connected to a junction structure up or down
- moving the bottom of a junction structure (sump) up or down
These changes to level in the junction structure’s cover, connected pipes, or sump, could occur because the structure is grip edited, or because the referenced surface is edited, or because a connected pipe level is moved. Any of these types of edits may result in level changes to parts of the structure.
Moving the Cover
When a junction structure’s cover (top of structure) is moved up, the cover simply moves to the new level. Connected pipes, and sump levels, remain unchanged.
If you try to move a junction structure’s cover down, to a level where it violates the vertical pipe clearance area, you will not be able do so. The cover must always be located above the vertical pipe clearance area.
Moving Connected Pipes
When a pipe that is connected to a junction structure is moved up, to the point where it violates the vertical pipe clearance, the top (cover) of the structure automatically moves up so that the pipe does not touch the vertical pipe clearance area. In this case, the structure’s cover level changes (moves up).
If you move the pipe up, but not to the point where it touches the vertical pipe clearance area, then the pipe is moved up, but the rest of the structure remains where it is. In this case, the structure’s cover level remains unchanged.
Understanding the Control Sump By Property
When you are moving a connected pipe down, there is a part property associated with the junction structure that affects the structure resize behaviour in this situation. That property is the Control Sump By property, and it can be set to Depth or Level. When this property is set to Depth, the sump depth is controlled by the depth, based on the lowest pipe invert. When this property is set to Level, the sump depth is controlled by the level value of the sump. The resize behaviour is different depending on how this property is set on the structure.
When a connected pipe is moved down, to a point where the pipe moves below the connected structure’s sump level, and the Control Sump By property is set to Depth, since the sump level is set to be controlled by the depth, then the sump level will be moved down, to a new level. This new sump level will be the depth of the lowest pipe invert, minus the sump depth value.
If a connected pipe is moved down, to a point where the pipe moves below the connected structure’s sump level, but the Control Sump By property is set to Level, then the sump will automatically move down, to a level equal to the lowest pipe level. This sets the sump depth to zero.
Moving the Sump
Using the sump depth grip, you can move a junction structure’s sump up to the point where it meets the lowest connected pipe. You will be prohibited, however, from moving the sump up past the point where it touches the lowest connected pipe.
When you move a junction structure’s sump down, the sump will simply move to the new level, and not affect any connected pipes, or the structure’s cover. This behaviour is the same whether the sump is controlled by depth or by level.
Moving Junction Structures That Are Not Connected Pipes
When there are no pipes connected to a junction structure, the cover and vertical pipe clearance take precedence over the sump.
Moving the Cover
When you move the structure’s cover up, and the Control Sump By property is set to Depth, the sump moves up the same distance as the cover.
When you move the structure’s cover up, and the Control Sump By property is set to Level, the sump moves up the same distance as the cover.
When you move the structure’s cover down, the sump does not move. You can move the cover down, but only to a location just above the sump. The cover must always be above the sump.
The following sections describe the resize behaviours on junction structures that have no connected pipes.
Moving the Sump
When you move the structure’s sump up, and the Control Sump By property is set to Depth, the new sump level can be below, at, or above the vertical pipe clearance area. This does not affect the cover level, and it sets the sump depth to zero.
When you move the structure’s sump up, and the Control Sump By property is set to Level, the sump can only move up as far as the bottom of the vertical pipe clearance area.
When you move the structure’s sump down, the sump is moved to its new location (new sump depth), but the cover level does not change.
Structure Height Limitations
Structures are limited to a minimum and maximum height from the structure's rim to its sump. The current value of the structure's height from the rim to the sump is shown in the Structure Properties as the Rim to Sump Height. The allowed range is based on the part's SRS (structure rim to sump) parameter. The SRS parameter is a range with minimum, maximum and default values. The structure cannot be edited to fall outside of this range. A warning message will appear in the Event Viewer when attempting to make an edit that would create a structure height outside the allowed range.
If the structure rim to sump range is not adequate for the current design, it can be changed in the part editing tool used to create the structure. If the part was created with Part Builder, that tool can be used to edit the minimum and maximum height for the SRS parameter. If the part was created with Infrastructure Parts Editor, the minimum and maximum height values can be edited in the part's .XML file. For more information, see Editing Parts with Part Builder and To publish a parts catalogue to Autodesk InfraWorks or Autodesk Civil 3D.