Running a standard clash detection in Navisworks

The Clash Detective in Navisworks is really one of the most robust features of the program.  It allows the user to explore a project much further than ever before possible.  In fact it really is a leap forward from the CAD days and is one of the primary benefits of Building Information Modeling (BIM).  Construction firms have really taken off with Navisworks, and by using the Clash Detective feature in the program they are saving time and money by finding errors and omissions in the project virtually before construction.  I am also seeing many architecture firms start to utilize this software.  Running a clash detection with the coordination teams and consultants is helping them identify where changes need to occur long before construction and respond in the proper manner.  

The Clash detective in Navisworks goes beyond the act of simply clashing objects together and visually seeing the results.  In addition to a traditional clash, the user can create reports, set up a predefined clash test, create rules, set viewpoints, and group clashes.  However, as cool at the Clash Detective is, it doesn’t come with all versions of Navisworks.  Below is the list different versions.

Three Navisworks Versions:
  • Navisworks manage
    • Comes with the Building Design Suite Ultimate.  The clash detective is included in this version.
  • Navisworks Simulate
    • Comes with the Building Design Suite Premium
    • No Clash Detection
  • Navisworks Freedom
    • Free Viewer
    • Must open a .NWD File
    • Nothing more than a viewer with this version.
This is definitely one of the features that sets Navisworks Manage apart from Navisworks Simulate.  This powerful tool allows us access to construction before construction begins, and is really the heart of BIM modeling.  This is really where Navisworks blows Revit away because it allows you to drill into specific clashes with similar objects or systems. Revit looks at the entire model, and with Navisworks you can fine tune the specifics of a clash detection.

Creating a Clash Test and setting rules.

In Order to run a clash you must have two selections to compare against.  For example you can’t compare the same architectural model against itself.  There would be zero clashes.  However, you can compare a mechanical model with a sprinkler model or an architectural with structural, etc...  The idea here to compare one system against another.  I’ve imported in 5 different models.  Architectural, Mechanical, Sprinkler, Electrical, and Structural.
The Clash Detective command is found under the home tab and on the tools panel.

Creating a clash test and setting rules in Navisworks

Click on the Add Test and create a new test.  This will open up the detective dialog box.  

Add test button in clash test in Navisworks

Click on the text “Test 1”  rename this to what you want.  In my example, I will call it “mechanical to sprinkler”.  Tabs are displayed below showing Rules tab, Select tab, Results tab, and Report tab.

Rename column in clash test in Navisworks

Selecting Objects to clash and adding clearances:

Select the objects to clash under both “Selection A” and “Selection B”.  

Selections in clash test in Navisworks

This will set you up for success when you run your test.  Down below there is a series of buttons which tell the software what you want to clash.  Depending on the design software you are using, this could be different.  The three types are Surfaces, Lines, and Points.  Since my models came out of Revit, I’m going to select surfaces.

If you don’t select anything you will have zero clashes.  Lines are for CAD data, and Points are used when clashing point clouds.  

When you have both systems selected click on the Run Test button at the bottom of the detective dialog box.

After running the test, Navisworks will display the results both in a graphical format and a report format.  The graphical format is over on the right and Navisworks will automatically zoom you to the location of the first clash.   By default you will see red items clashing with green items.  In my example, the red items are the HVAC systems clashing with green sprinkler systems.  Everything else in the model is converted to a wireframe mode.  It’s actually pretty cool looking!  In the example below, the clash between the two systems is very evident.

HVAC and sprinkler systems clash in Navisworks

Here is a screen capture of the clashes listed.  

Clash list in Navisworks

In the next blog I will describe how to create reports and resolve clashes.


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