Clash Detection

Clash detection, coordination analysis and data checks shall be carried out by the BIM Coordinators against the latest shared models. The workflows involve a combination of visual and automated checks which are curated into issues and reported back to the team via an online Issue Management System.

A detailed appraisal of the Lead Appointed Party Coordination procedure should be be includedd in the BIM Coordination & Audit Procedure, BEP shall include main points only.

The Clash Detection includes the agreed project clash sets, type of clash (hard or clearance) and agreed tolerances. This is a live information container that will be reviewed and updated throughout the project as required.

Clash detection is to be typically carried out using clearance clash type settings in line with specified installation tolerances. This is to include any unique manufacturer’s requirements, for example, clearance required for intumescent coatings to effectively expand.

Clash detection

The diagram summarises the clash status/resolution workflow.

Below is an example of Clash management priocess.

Following identification of a clash/issue within the model, the BIM Coordinator shall assign one of three statuses:

  • ‘New’ status, along with a unique number, is assigned to every item not previously identified.
  • ‘Active’ status is assigned to any clash/issue that has previously been identified but has been neither ‘Resolved’ nor ‘Approved’ during the previous review cycle (model changes may have been made but have not solved the clash/issue).
  • ‘Resolved’ status is assigned to any previously raised clash/issue that has now been solved through adjustments made in the model.

All ‘New’ and ‘Active’ items will be reviewed at the fortnightly BIM Coordination Meeting (BCM) and a further status assigned:

  • ‘Approved’ status is assigned to any item considered to be a non-issue, e.g. a concrete column clashing with a concrete slab (consideration, however, needs to be given to the model Use, for example, if the model is intended for 5D quantification then the noted column example may not be acceptable).
  • ‘Reviewed’ status is assigned when it has been agreed that a change to the model is required and responsible for implementing the change has been designated.
  • ‘Active’ status is assigned when an issue is acknowledged as valid but will not be resolved during the current phase, e.g. pipes passing through a concrete wall flagged up as a clash during the design stage, but no action required, as a builders work opening will be added to the model during the detailed design phase or following a design freeze.
  • Clash analysis should be presented in the form of a report to compare the different clashes, record the clash detection and assumption on elements tolerances, areas and elements, identify any significant conflict discovered in the process and generate resolution result summary. The report shall address the following.
  • Software to be used
  • Workflow overview
  • Responsibilities
  • Outputs
  • Technical query workflow
  • Clash resolution workflow
  • An action plan with target completion schedule to handle and resolve detected clashes
  • Tolerance levels (mm) for different discipline
  • Operation clearance
  • Maintenance clearance
  • Buildability
  • Service compatibility

A clash/issue with an ‘Active’ status will be reviewed again as appropriate at the BCM.

[source] PDE 4301 Technical BIM Management 2019/2020, BIM EXECUTION PLAN, SUP-GPF-XX-XX-SP-W-0001, Post-appointment BEP, Grat To King Yeung, Jarek Wityk, Mike Sealey, Tala Damra, Viorel Mihailuc, Willow Williams

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