Multi-Corridor Parameter Control

The Revit Cross-Family Restriction

In Revit, when you select multiple instances in the model and open Properties, Revit only shows parameters that are shared across all selected element types. If you select two corridor segments from different families — even if both have a parameter named Depth — Revit will show no parameters at all unless both instances are of the same family type.

This is a hard platform limitation. It means editing a corridor that spans multiple span families (common in long bridges) requires opening each segment individually, one at a time.

Browse and Search Available Instances

On form load, PopulateLayerComboBox() scans all FamilyInstance objects in the project for those that have either a SubcategorySolid or SubcategoryVoid parameter. These are the AutoBRIDGE corridor and slab families. Each matching element's name is added to listBox1.

The search box (textBox1) above the list filters in real time. Each keystroke clears listBox1 and repopulates it from the original name list, keeping only items containing the search text (case-insensitive).

Multi-Select Instances

listBox1 uses SelectionMode.MultiExtended — the same familiar keyboard behaviour as Windows Explorer:

• Click — select one item, deselect others
• Ctrl + Click — toggle individual items without losing other selections
• Shift + Click — select a contiguous range

Select as many instances as you need — there is no limit.

Transfer Instances with >> and <<

Select items in listBox1 and click >> to move them to listBox2 (Selected Instances). The moved items are removed from listBox1 to keep the lists mutually exclusive. Click << to return selected items from listBox2 back to listBox1.

Every time listBox2 is changed — either by adding or removing items — PopulateCommonParameters() runs automatically to refresh the parameter grid below.

How Parameters Are Collected

PopulateCommonParameters() loops through every element in listBox2, reads all their parameters, and aggregates them into the grid. Only writable parameters of type Double, Angle, or String are included. Read-only and the following internal AutoBRIDGE parameters are excluded:

• SubcategorySolid / SubcategoryVoid — category assignment parameters
• InitialRotation / AutoBRIDGE_Type — system parameters
• IFC parameters (IfcGUID, IFC Predefined Type, etc.)

Understand the Three Columns

Edit Parameter Values

Tick the Activate checkbox on any row to make its Value cell editable. Type the new value in metres for length parameters, or degrees for angles. The grid does not validate units during input — the conversion happens at RUN time.

Click RUN — One Transaction for All Instances

The button8_Click handler opens a Revit transaction named "Update Parameters" and loops through every row in the grid. For each activated row with a valid (non-[varies]) value, it loops through every element name in listBox2 and:

1. Retrieves the element by name from the document
2. Looks up the parameter by name via LookupParameter()
3. Compares the current value to the new value — only updates if different
4. Converts the input back to Revit internal units: metres → feet (÷ 0.3048), degrees → radians (× π/180)
5. Writes the value and records the parameter name in the updated list

Transaction Committed — Success Dialog

After the loop completes, the transaction is committed. A success TaskDialog lists the names of all parameters that were actually updated. If no values differed (all were already at the target), the dialog reports "No parameters were updated."