BIM coordination involves more than clicking a button and watching the computer do all the issue identification for you. It is actually a workflow that requires a team approach and preparation from the beginning. Proper management of data and personnel leads to successful BIM coordination.
Organizing from the Beginning
In order to keep a fluid workflow and proper documentation trail, it is imperative that the BIM team meet together before any modeling takes place. This meeting is commonly called the BIM Kickoff meeting. This meeting should address, at a minimum, the schedule, file naming convention, standard modeling locations, file transfer methods, and software versions.
Compiling the NWF
The real test of the BIM kickoff meeting begins when files start pouring in from different disciplines. It is not at all uncommon to compile models together only to discover that they do not line up as shown in Figure 1. Sometimes the distance between these models can be thousands of feet. This is a big problem because even if the offending model is corrected in Autodesk® Navisworks, the model will still cause issues to any other party referencing the offending model. The team member assigned as the BIM Lead needs to manage the situation and ensure the offending model is moved to its proper place.
Figure 1: Models not properly aligned.
Once the model files have been properly placed, the analysis of the models begins. The first step to ensure an efficient workflow is to set up proper search sets and selection sets. The sets you create serve many purposes; common sets are used for Clash Detective rules, hide/unhide areas, and special clash tests.
The Clash Detective sets rules that are commonly forgotten. Navisworks has the capability to allow you to quickly narrow down your Clash analysis by ignoring false positives. For example, if you are running a Clash test between the electrical system and the ceiling system you will get hundreds of false positives of ceiling flush lights. These hundreds of clashes cloud up the real problems and waste the BIM Lead’s time when the clash is run. In order to properly manage this, you can create special clash rules based on sets. In the example listed above, you would create a set containing all the flush mounted lights and name the set lights. You would then create another search set called ceilings. In the Clash Detective under the rules tab you would create a new rule ignoring clashes between the two sets as shown in figure 2 below. Then run the clash with the rules checked and watch as the real issues become clear.
Figure 2: Clash Detective rules
Another key use for selection/search sets is hiding and un-hiding key parts of the building. During the BIM process, objects in the model are hidden and un-hidden frequently. Common sets are light clouds from Revit, ceilings, walls, and any other large covering object (foundations, topography, etc.). By creating these sets the BIM Lead can quickly show any part of the building without being hampered by common obstructions.
Selection sets can also be used to run special analysis on groups of objects. For instance, when running clash detection against an architectural model, it often becomes beneficial to break up the model into different systems for issue identification. It becomes beneficial to run a clash against the ceiling search set and the MEP systems. Other architectural systems are likewise clashed against other disciplines. By breaking up files, more specific problem identification becomes possible.
Figure 3: Clash batches
Preparing for a BIM Coordination
Once the model has been compiled and the search/selection sets have been created, it is time to run the Clash Detective. Clash batches should be created for each discipline against every other discipline. Once the batches are set up, it is time to run all the different clashes. Generally, when the Clash Detective is run, hundreds of clashes appear. A best practice is to identify true problem issues and remove duplicate issues. Because Navisworks is only clashing triangle faces against other triangle faces, one pipe fitting hitting steel could represent 20 clashes when in reality it is one issue. Therefore, it is necessary to group all duplicates into a folder and all the real issues into another folder.
An issue should identify all the clashes caused by a continuous object. For instance, if a plumbing line is running through eight wide flange beams, the eight hits should be identified by the same issue with the remaining hits being marked as duplicates. Figure 4 shows four plumbing lines going through an electrical duct bank. These four lines constitute nine different clashes, when in reality all four lines represent only one issue. The lines were marked together as one issue, placed in a folder, and the other duplicate clashes of this issue were placed into a reviewed folder.
Figure 4: Plumbing electrical issue
One of the many benefits of separating issues from duplicate clashes is that it allows the coordination meetings to be efficient and effective. By pre-identifying the issues, the BIM team can look for solutions rather than looking for problems.
Running the Coordination Meeting
Now that all of the early preparation of issue identification has been done, the BIM team meets together. During this meeting, issues are reviewed. One idea to ensure each discipline’s time is respected is to stagger the attendees. Consider inviting the two disciplines with the most conflicts in the beginning and then slowly adding other disciplines to the meeting. Since no one wants to sit in a meeting without participating, this method allows each member to feel his/her time is respected, which in turn increases team collaboration.
While looking at the issues with the team often you will need to navigate the issue to get different perspectives. If you pre-redline all the issues before the meeting begins, you can navigate the issue with the team. When you need to refer back to the original view you can simply click the clash to be referenced back to the original view. The redline actually anchors the clash to the view in which you drew the redline. The redline also helps to clearly identify the clash for the team when they review the report from the meeting.
Once a resolution has been decided upon by the team, documentation becomes critical to help remind each party of his/her responsibility. One method of this documentation is the use of comments. You can tag each issue with a comment to notate the clash resolution and responsibility as shown in Figure 5. You also have the option of assigning responsibility to a discipline by assigning it in the Clash Detective window.
Figure 5: Clash resolution
After each issue has a resolution, the team should review upcoming milestones on the BIM schedule. By reminding the team about the schedule frequently, the team has the ability to properly manage their time and resources to ensure milestones are met.
After the meeting, it is the BIM Lead’s responsibility to create a report detailing the resolution of each issue and responsibility of each party. This report can be generated from Navisworks in viewpoints, html, or xml formats. Often, it is advantageous to post a couple of different types of reports since each member of the team might have different internal methods for reviewing and fixing issues. Regardless of the method, the report is critical for the team’s success. The type of reports the team requires should have been identified in the BIM Kickoff meeting. Typically, a NWD is issued along with an annotated report in excel or html.
When each discipline posts its corrected files, the discipline should not change the filename. By keeping the same filename, the old file can be overwritten and linked in properly to the NWF. Since the NWF is the heart of the data analysis, it is important to maintain the same name and location of all the files. Note: Never work from an NWD—it is only a snapshot of the NWF. Some type of version control should be implemented to backup the files in case of file corruption.
Once the latest files have been placed in the proper location, the NWF is opened and the clashes are re-run. Every clash that has been resolved will have its status changed automatically to “resolved.” This can prove problematic for the issues you identified because the clash on which you identified the issue might have been resolved while the entire issue was not resolved.
In cases like this, simply change the status of the issue to active. If the issue was resolved, simply remove the issue from your current issue folder and place it in a different location. If you wish to remove all the resolved problems so they do not show up as hits in your model, remove the resolved clashes from their folders and press the compact button on the Batch tab. The compact button removes all resolved issues that are not in folders.
Now that the clashes have been re-run and the resolved issues have been archived or removed, it is time to identify all of the new issues in the compiled model. The cycle of drawings being submitted, issues being identified, the team meeting together resolving issues, and correction being re-posted will continue until the model is fully coordinated. A simple workflow diagram is shown below.
Figure 6: BIM workflow
To sum up, managing BIM coordination is more than just knowing how to click a button in Navisworks. It is creating a workflow between different team members and creating and regulating the rules necessary for the project’s success.