Clash FAQ
- What is an unsuccessful clash check?
- How can I fix an unsuccessful clash check?
- Why can I see my latest models in Clash Settings, but not in the rest of Model Coordination?
- What is the yellow warning icon in my coordination space?
- Why can I see clashes between two objects that are at different levels and aren't intersecting?
What is an unsuccessful clash check?
An clash check is unsuccessful when it fails or times out. The most common reason is because there is too much clash data, caused by:
- A large number of models in the coordination space.
- Models of large sizes.
- Models with complex geometry resulting in a high number of clashes.
- Models with similar or duplicate geometry resulting in a high number of clashes.
Even if a clash check is successful, too much clash data can negatively impact performance. Signs that there is a large amount of clash data include:
- The Clashes column on the Models page takes a while (ten or more seconds) to load.
- The Clashes panel in the viewer takes several seconds to load, or does not load at all.
- There are many models turned on for automatic clash detection. While clash success is also dependent on each models' complexity and size, unsuccessful clash checks become more common when there are 450 or more models included in the clash check.
- The numbers in the Clashes column and clash grid are large (more than 10000 clashes across many models).
- Different models in the clash grid show similar clash counts, suggesting that they may be duplicates.
If the latest clash check is unsuccessful, Model Coordination will show one of two error messages by the coordination space picker:
| Error | Details |
|---|---|
| Can't display latest models | The clash check on the latest models has failed, so Model Coordination shows the models involved in the most recent successful clash check. This means that Model Coordination could be showing older model versions, models that have since been deleted from the folder, or be missing newer models which are in the folder.  |
| Clash check unsuccessful | This means there has never been a successful clash check in the coordination space. Model Coordination shows the latest models in the coordination space, but without any clash results.  |
How can I fix an unsuccessful clash check?
Most unsuccessful clash checks are due to an excessive amount of clash data. One way project administrators can reduce clash data is by removing duplicate or redundant content from the clash check:
If you have models representing each area or level of a project, and also a federated model containing all of those individual models again, try turning clash off for the federated model. Alternatively, remove the federated model from the coordination space.
If you've uploaded models containing linked models, try creating object exclusions that exclude the linked model content from clash. Alternatively, recreate the 3D views without any linked models.
If you have the same components or systems, for example walls, represented in multiple models or views, try turning clash off for the redundant models, or creating object exclusions to exclude specific objects from clash.
Other ways to reduce the amount of clash data include:
Creating object exclusions to remove objects from clash that are not a priority for coordination, such as bolts, flex ducts, and hangers.
Creating multiple coordination spaces and having fewer models in each. For example, create a coordination space for each building in a project, or for each level of a building, or phase of a project.
Reducing the size of your models. For example, publishing fewer views from your Revit models.
There are also various causes that can't be solved by reducing model numbers or size, or changing your coordination space setup. If these troubleshooting steps don't work, or you experience a spinner on the Clashes tab that doesn't resolve, the support team can investigate and help to resolve the error.
Why can I see my latest models in Clash Settings, but not in the rest of Model Coordination?
The Clash Settings page always shows the models involved in the last clash check, whether the clash check was successful or not.
If the last clash check failed, Model Coordination may be showing models from a previous successful clash check, while Clash Settings shows the models from the failed clash check. This would mean that Clash Settings shows a more up-to-date list of models than the rest of Model Coordination.
Data in the Clashes column will reflect the last successful clash check, even inside Clash Settings.
What is the yellow warning icon in my coordination space?
If you see this icon 
on the coordination space picker, it means that the clash check has processed successfully overall, but certain models couldn't be checked.
The specific models will be marked with the yellow warning icon next to the model's name in the Models and Clashes pages. These models do not show any clash data because something has gone wrong when processing the models for clash.
This is often due to temporary problems and can be resolved by simply uploading the model again to Document Management. Try this before attempting another solution. If re-uploading the model does not solve the problem, then contact support.
Why can I see clashes between two objects that are at different levels and aren't intersecting?
Applies to
This scenario only applies when all the following criteria are fulfilled:
- Revit file
- In V2 coordination space
- The Revit file broken down into Revit views (for example, by level) and an object in the model spans multiple views.
Example
A common example is a column or wall that extends through multiple levels, with a Revit view defined for each level. These kinds of objects can show as clashing against another object that they are not visibly touching due to the objects clashing in a different Revit view.
Reason
Clash in V2 coordination spaces uses the Revit master model view (all geometry in the Revit file) instead of using the model geometry in each Revit view. We use the master model view to optimize clash performance.
Model Coordination clash is based on object IDs, and when an object spans multiple Revit views it will still retain the same object ID. Clashes in the viewer are then shown by highlighting the two objects (based on the object IDs). This can result in two objects which may not be visibly touching showing as a clash, due to these objects clashing in a different Revit view.
Remove the clashes by
When a clash is noted as an issue or a not an issue, it will remove all instances of this clash across multiple Revit views.