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Navisworks clash deep dive 1: configuration

Navisworks clash detection is a powerful BIM tool, widely used in the construction sector. This article expands on how to set up and run it correctly.

As we discussed in a previous article, Navisworks is a great software for BIM projects. It allows project teams and stakeholders to coordinate more efficiently and effectively. Thanks to its simple and user-friendly interface, it is fairly easy to learn, which multiplies its potential. One of its main advantages is the ability to visualise projects and how the different elements interact between them. But arguably the most powerful resource within Navisworks is the clash detection tool. Although it only ships with the paid Navisworks Manage version, the investment is totally worthwhile. The clash detective can highlight all the clashes between different models and assets. This, in turn, helps to minimise expensive errors and changes on-site, as they can be resolved during the technical design and construction stages, prior to fabrication and install.

Navisworks MEP model

Before the initial steps

Setting up and running Navisworks clash detection for the first time can be a daunting prospect for inexperienced users. Having run through the process countless times before, allow us to shed some light on the steps involved.

Firstly, ensure you have Navisworks Manage installed, otherwise, you will not be able to access the clash detective. Before you open Navisworks Manage, you need to export the individual models from their native software (Revit, Tekla, Civil 3D etc.) to a Navisworks format. Just open each of the linked models and export *.nwc files to create the base Navisworks cached models. Next, create the master *.nwf model for the project by opening Navisworks and name it based on the project model number. Save files in a specific Navisworks folder so that they are easy to find.

Setting up Navisworks clash detection

After producing sufficient modelling, export a work in progress (WIP) model from the native software and append to the master project Navisworks model using the native project file name. In the project’s Navisworks model create some views (viewpoints) for the different levels or areas so that clients and stakeholders can easily navigate through what will become the Navisworks federated (NWD) model. For example, if you are modelling a building, you can add views for the different levels and elevations. If you are working on a highway, you can save a view of the overall plan, and then some views at the main chainages.

After the master model is set up in Navisworks, we recommend performing a daily export to update the Navisworks model and synchronise to your Common Data Environment. This will ensure the latest content is always available to all project team members and other stakeholders.

When preparing the project model clash detection scenarios, follow a similar naming convention to the one below (where PRJ = project code and ORG = originator code):

  • PRJ-ORG-01-XX-M3-M-001_Mechanical vs Electrical
  • PRJ-ORG-01-XX-M3-M-001_Mechanical vs Structure
  • PRJ-ORG-01-XX-M3-M-001_Electrical vs Structure

The clash scenarios (report names) for the client will typically follow the model naming followed by the discipline to be clashed with. If a specific model naming convention is required based on the client BIM Execution Plan (BEP), then revert to the BEP.

Tolerances and clash reports

When setting up the Navisworks clash detection tolerances, use a type suitable for the project e.g. ‘hard’ and link ‘none’. Make sure you check the box for ‘composite object clashing’ and set the tolerance to the required value e.g. 0.025m. Of course, the tolerance may vary depending on the type of project, but generally, 0.025m is a good rule of thumb. Additionally, you may want to change the type to ‘hard (conservative)’. This will provide a more thorough clash detection, although it may also return more ‘false’ clashes.

Once you have gone through the reports and made relevant clashes active, export each report using the HTML tabular option and save the reports in a relevant Clash Reports dated folder. Before publishing the reports to HTML, change the Navisworks logo jpeg to that of the client in the folder ‘C:\Program Files\Autodesk\Navisworks Manage 201x\Images’. To do this, rename ‘logo.jpg’ to ‘logo (old).jpg’. Copy your client logo to the relevant folder and rename client logo to ‘logo.jpg’. This way Navisworks will write the client’s logo to the HTML tabular report for easier formatting. After this step, you can push the reports to MS Excel giving the client an option of viewing HTML or MS Excel.

A practical example of Navisworks clash detection

By way of an example, let us walk together through a building project where we carried out Navisworks clash detection.

  1. Export the models from Revit to Navisworks. Set the coordinates to ‘Project Internal’ and switch off the option ‘Divide File into Levels’.
  2. Prepare the clash test, including rule definitions. Switch on the option ‘Items with coincident snap points’.
  3. Choose the required elements and specify the clash type and tolerance. Note that we ran clash reporting for insulation as a separate test.
  4. Sort and group clashes manually by service type and room/area. Note that all collisions are grouped according to the relevant elements. For example, the internal VRF units include clashes with ducts, air terminals, pipes.
  5. Prepare clash views.
  6. Export clash reports to HTML (Tabular) format.
  7. You can then export a set of clash tests as a template or to share the clash tests. Tests can be exported/imported as needed (XML format).

Have you tried the Navisworks clash detection tool already? What do you think about it? Let us know in the comments below.

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