Create a clash test

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The Clash Detective tool enables you to search through your total project model,

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identifying cross-discipline interferences, or clashes, earlier in the design process.

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This eliminates the manual process of inspecting and identifying clashes in a 3D project model.

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Early clash detection helps to keep the construction costs down

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by reducing the number of change orders caused by objects occupying the same space.

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In addition to checking stationary objects in the building, you can check mobile objects, such as cranes,

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to ensure that construction equipment does not collide with anything on the project site.

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Here is a high-level workflow for the Clash Detective:

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Start by setting the ignore clash rules.

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This will help to minimize false clashes between items on the same layer, within the same block group or cell,

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or items with the same snap points.

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Understanding these ignore rules can make your results more meaningful.

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Once you set the rules for your test, select the required items to be included in the test.

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The items selected under selection A are compared against the items selected under selection B,

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such as structural framing versus plumbing.

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Next, use the clash settings to set the type of clash test to be run:

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A Hard clash highlights objects that reside in the same space or intersect each other,

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while a Hard (Conservative) clash returns objects that might clash.

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With a conservative test, you can get more false positives, although it is much more thorough.

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A Clearance clash test enables you to set a minimum distance between objects,

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such as a water line and a sewer line that must be a certain distance away from each other for sanitary reasons.

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Use the Tolerance field to set the minimum distance for the Clearance test.

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A Duplicates test returns objects of the same type that reside in the same space,

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making it easier to delete any duplicate items.

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To run a clash test, from the Home tab, Tools panel, click Clash Detective.

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The Clash Detective can be docked or floated, as needed.

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Click Add Test to add a new test., then double-click the test and give it a meaningful name, such as "Plumbing versus Structure".

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Next, on the Rules tab, you can indicate which rules to use.

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Remember that you can have the test ignore items on the same layer, in the same group block or cell, or in the same file,

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as well as items with coincidence snap points.

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For this example, select all four ignore rules.

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Switch to the Select tab.

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Here, you select the items you want to compare against each other.

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For example, in Selection A, select your structural file, and in Selection B, select your plumbing file.

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Scroll down to the Settings group, and for this example, set the Type to Hard.

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Click Run Test to run your selected clash test.

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The Results tab automatically displays to allow you to interactively review the found clashes.

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Scroll up to see a summary of how many clashes were found between the plumbing and structural members of the building.

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In the Results Area, clashes are displayed in a multi-column table to enable you to locate clashes more easily.

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Expand the Display Settings to enable efficient reviewing of clashes.

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For example, you can change the colors displayed for Item 1 and Item 2.

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If you have a cluttered model, you can use the Isolation options to dim or hide items that are not involved in the selected clash.

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To review a clash in the model, select it in the results list.

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Here, select Clash 5. Then, move the Clash Detective window aside to view the model.

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You can see that the pipe extends through the floor.

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In this case, you may need to communicate with the structural engineer to find out if this is allowable.