Example of a Clash Condition Isolated in Revit

The clash detection and resolution process has evolved into a mainstream, scheduled activity during the design process and has slowly established itself as a standard quality control activity in most BIM Execution Plans. Not all clashes are issues, but of the identified clashes there are many that the BIM coordination team will be able to flag as coordination issues. These issues, typically referred to as 'Requests for Information' (RFIs)  are distributed for resolution during coordination meetings, with a list of 'Action Items' assigned to every consultant or sub-contractor. The current product-based tools fall short.  There is the 'Switchback' feature that lets you go from a clash in Navisworks to its location in Revit - but that assumes you have both products. Otherwise, there is no automatic exchange of RFIs between products. You could view them in a Navisworks Freedom clash file but then you are left with the task of finding them in the Revit model, something that a Revit schedule can readily do.  Since both products can exchange data with an Excel spreadsheet, there is an opportunity to expedite the process. You can share a  'Schedule of Open Issues' created from Navisworks with Excel, manage the data, then push the data to a Revit Schedule, from which you can locate the clashes. The workflow involves four steps:

  • In Revit, create several parameters across the model categories to document the issues.
  • Export the empty Schedule of Issues to Excel as an RFI Schedule.
  • Map the Navisworks generated clashes (exported HTML report) into the RFI Schedule.
  • Import the worksheet into Revit using Ideate BIMLink.

RFI Schedule Built in Revit

Let's explore these steps in greater detail:

  1. Create parameters across the model geometries and build a 'RFI Schedule': Create new Multi-Category project parameters to document the RFI. In this example you create three custom parameters to keep your schedule short. Additional fields could be added as needed. The parameters created are:
    • Clash Name:  Holds the Clash name coming from the Navisworks Report.
    • Clash Cleared?: A Yes/No parameter that shows if the clash is active.
    • Comments:  Coordination follow-ups, issues, other instructions to the BIM modelers.
  1. Export the empty Schedule of Issues in Excel format: You use Ideate BIMLink to create a multi-category 'link' of user parameters that are then exported into an .xls file.  This schedule will be empty of parameter values but will contain the Element ID of every object in the project. Note that the multi-category link in Ideate BIMLink includes both system family (walls, ducts, etc.) and the other custom families (equipment, air terminals, devices, etc.).

    Export the Multi-category Parameters as an Excel File Using Ideate BIMLink
  2. Map the Navisworks Report into the Schedule of Issues: The HTML tabular report generated by Navisworks can be opened and saved in Excel format. You nest this report as a worksheet tab in the BIMLink exported RFI Schedule. The report can be reformatted to display a limited amount of information, or the data can be grouped to display information in a single column (using the Excel formula CONCATENATE).  You can also customize the report to include Clash Priorities, the counterpart clash ID number, and/or any other additional consultant notes. Next, map the Clash Report parameters to the schedule using the "Identity Data" field as the key identifier, and using the Excel formula VLOOKUP to associate a string of information from one database into another.

    The formula arguments of VLOOKUP are not difficult to understand:

    Excel VLOOKUP Formula Explanation
  • What unique identifier are you looking up in the database? (Element ID)
  • Where is the database? (The Navisworks Report range of values)
  • Which column of the database, associated with the unique identifier, do you wish to have retrieved for you? (Second Column from the left)
  • Range_lookup is an optional argument, that has to do ascending or descending order of the identifiers; it requires to be either a TRUE or FALSE value, or it can be be left blank.

    The mapping of information is generated in the same Excel link file. New worksheets or working columns added to the link file will affect the import action.
  1. Import the Schedule into Revit:  This will populate the Schedule of RFI with the Navisworks data. The RFI Schedule of open issues will enable location of the issues in Revit and speed the resolution.  To review any open issue, the user can highlight the element in the schedule, and then show the desired object for resolution, or apply the Isolate view control.  When an issue is solved, you would mark the checkbox parameter as "Resolved", and/or add a date or any other note in the comment field.  New issues/clashes can be added or removed as the design evolves over time. This workflow would be a valid approach for Revit generated models. Non-Revit models would need to follow the traditional resolution process.  A limitation within Revit, is the inability to confirm ID numbers of objects in linked models. In Federated, Revit-based models, you can color-code the counterpart clashing elements thru the use of filters based on the custom 'clash' parameter (ie. Yes/No clash parameter).  The filter will apply a material or surface override to all the elements identified as clashes, which then would be retrieved across linked files via Visibility Graphics Overrides (VG > Revit Links > Custom > Filters). For a consistent, coordination review across multiple disciplines, you can document this process and include the detail, format and use of review filters in the BIM execution plan.

Filter Created Across Files to Highlight Clashes

Consultants can keep track of the resolution progress within Revit and issue progress reports during coordination meetings.  New issues resulting from new Clash Reports can always be added by repeating the workflow anytime. While this workflow is not full automation of the tracking process of an RFI, it is certainly helps to streamline bridging Navisworks and Revit. Interested on adopting this workflow?  Contact us at [email protected] .

About the Author

César Escalante - AIA, CCCA AEC Application Specialist
César is a licensed Architect with more than 12 years of experience leveraging architecture, design, and construction technologies in the AEC industry. He has an extensive expertise managing, implementing, and supporting all facets of BIM, IPD, and VCD workflows that includes the use of mobile and cloud technology during design and construction. César has played an instrumental role deploying successful strategies for multidiscipline coordination of large, technically complex, multimillion dollar projects. An innovative thinker, he is recognized as a leader at the forefront of BIM technologies, and he is a passionate educator. César is a LEED accredited professional and a Certified Construction Contract Administrator. He is currently a member of the buildingSMART alliance and the National Institute of Building Sciences. @VCDwhiz