BIM capability
Structured Navisworks clash detection with defined tolerance rules, prioritised issue management and documented resolution verification before construction issue approval.
Clash detection applies automated geometric intersection testing to federated models identifying hard clashes, clearance violations and workflow conflicts between discipline elements. Tests are configured with tolerance rules appropriate to system type, zone and construction sequence — not all intersections constitute actionable clashes.
Issue management assigns each clash to a responsible appointment with priority classification, target resolution date and linked model element identifiers. Open clashes are tracked through CDE or BIM issue platforms with status progression from identification through resolution to verified closure.
Resolution occurs in authoring models, not in the clash environment. After discipline teams update source models, clash tests are re-run to confirm closure. Construction issue gates require documented evidence that critical and major clashes are resolved or formally accepted as design intent.
Clash detection runs follow a defined schedule aligned to coordination milestones. Test sets are versioned with documented scope — which discipline pairs, which zones and which tolerance settings apply. Ad hoc testing without documented configuration produces inconsistent results that undermine coordination confidence.
Contractors and clients increasingly require clash detection reports as evidence of design coordination before construction mobilisation. Unmanaged clash programmes generate thousands of false positives that overwhelm resolution capacity, or miss genuine conflicts that become costly site variations.
BIM coordinators configure clash tests to match project risk profile — data centres demand tight clearance tolerances on cable trays; healthcare projects prioritise maintenance access around equipment. Tolerance tables are documented in the BIM execution plan and applied consistently across test cycles.
Clash resolution interacts with design change control, RFI processes and shop drawing approval. A resolved clash may require engineering recalculation, specification amendment or procurement variation. The issue management workflow links clash records to these downstream processes for traceability.
Hard, clearance and workflow test sets with documented tolerance rules per zone.
Discipline and zone element scopes defining clash test coverage.
Automated test execution at coordination milestone intervals.
Critical, major and minor classification based on constructability impact.
Responsible appointment allocation with target resolution dates.
Clash records linked to formal issue tracking platform with audit trail.
Re-run tests confirming closure after authoring model updates.
Documented design-intent conflicts formally approved without resolution.
Cycle-over-cycle metrics showing new, resolved and open clash counts.
Visual clash evidence attached to issue records for discipline teams.
Formal assessment of clash status before construction documentation approval.
Updated clearance rules when design standards or zone requirements change.
Define hard, clearance and workflow tolerances per system and zone in BEP.
Build Navisworks clash tests with selection sets and discipline pair rules.
Execute initial test against current federated models establishing baseline count.
Classify results and assign to responsible appointments in issue tracker.
Discipline teams modify source models to eliminate or accept clashes.
Execute clash tests on updated federation confirming closure.
Publish cycle report showing progress metrics and outstanding critical items.
Assess clash status against acceptance criteria before construction issue.
Every clash test has documented scope, tolerance and discipline pair definition.
Clash runs use federated models matching current CDE approved revisions.
Same tolerance values applied across test cycles unless formally amended.
Element scopes correctly isolate intended test coverage without omissions.
Critical, major and minor definitions documented and applied consistently.
Each clash linked to element identifiers, responsible party and model revision.
Closed clashes verified by re-run result, not manual status change alone.
Design-intent acceptances signed by authorised design lead or client representative.
Known false positives documented with exclusion rules to reduce noise.
Clash exports follow BEP-defined template with required data fields.
No open critical clashes at construction issue gate unless formally accepted.
Clash runs executed per agreed schedule without skipped milestones.
MEP vs structural
Ceiling void services
Plant room equipment
All discipline pairs
| Milestone | Element | Purpose | Responsible | Geometric | Alphanumeric | Documentation | LOD / LOIN | Control | Acceptance |
|---|---|---|---|---|---|---|---|---|---|
| First clash run | MEP vs structural | Identify major routing conflicts | BIM coordinator | LOD 300 MEP and structural models | Clash test ID, tolerance setting | Baseline clash report | LOIN 3 — coordination models | Test configuration audit | Baseline report issued to team |
| Design development | Ceiling void services | Clearance and routing optimisation | MEP BIM coordinator | All MEP systems in void | Priority classification, status | Weekly clash trend report | LOIN 3 at coordination gate | Re-run verification | Critical clashes assigned and tracked |
| Pre-construction | Plant room equipment | Installation access and maintenance clearance | MEP BIM lead | LOD 350+ equipment and connections | Maintenance zone parameters | Plant room clash clearance report | LOIN 4 — detailed geometry | Full room clash test | Zero open critical clashes |
| Construction issue | All discipline pairs | Construction readiness verification | BIM manager | Current federated models | Accepted clash register | Construction issue clash summary | LOIN 3–4 per matrix | Gate review checklist | Construction issue sign-off |
Clash detection results feed back into engineering design decisions — rerouting ductwork may require HVAC recalculation; relocating cable tray may affect voltage drop analysis. The issue management workflow flags clashes requiring engineering review versus those resolvable through spatial adjustment alone.
Prefabrication and modular construction packages depend on clash-free MEP assemblies. Dedicated clash test sets cover prefabricated zones with tighter tolerances than general building areas.
Fire stopping, acoustic lining and insulation zones appear as clearance requirements in clash tests. MEP elements must respect these non-physical boundaries defined as clearance volumes in the federated model.
ISO 19650-2
PAS 1192-2
Autodesk Navisworks
AIA LOD Specification
Client BEP
BS 1192
buildingSMART
GSA BIM Guide
| Standard / Reference | Full title | Organization | Application area | Relevance | Edition status |
|---|---|---|---|---|---|
| ISO 19650-2 | Organization and digitization of information about buildings and civil engineering works — Delivery phase | ISO | Coordination information | Information exchange requirements for clash detection deliverables. | Published — confirm edition at project start |
| PAS 1192-2 | Specification for information management for the capital/delivery phase of construction projects using BIM | BSI | Clash detection process | Coordination and clash detection workflow reference. | Published (2013) — superseded by ISO 19650 |
| Autodesk Navisworks | Navisworks Manage Clash Detection | Autodesk | Clash platform | Test configuration, reporting and issue management functionality. | Current platform version — confirm at project start |
| AIA LOD Specification | Level of Development Specification | AIA | Test readiness | Minimum LOD for meaningful clash detection results. | Published edition — confirm at project start |
| Client BEP | Project BIM Execution Plan | Project-specific | Clash programme | Tolerance tables, test schedule and acceptance criteria. | Project issue — confirm at appointment |
| BS 1192 | Collaborative production of architectural, engineering and construction information | BSI | Issue management | Status codes and issue tracking conventions. | Published — confirm edition at project start |
| buildingSMART | BCF — BIM Collaboration Format | buildingSMART | Issue exchange | Standardised clash issue data exchange between platforms. | buildingSMART specification |
| GSA BIM Guide | Spatial Coordination and Clash Detection Guidelines | GSA | Federal projects | Reference for US federal BIM clash detection requirements. | Published — confirm edition at project start |
Applicable standards depend on the project jurisdiction, information requirements, contract documents, delivery method and authority requirements. The adopted editions shall be confirmed at project commencement.
Tolerance tables, test definitions and schedule per BEP.
Navisworks tests with documented selection sets and rules.
Initial test results establishing coordination starting point.
Cycle metrics showing new, resolved and open clash counts.
Classified results with assignment and target dates.
CDE-linked clash issues with status progression and audit trail.
Re-run results confirming closure of assigned clashes.
Formally approved design-intent conflicts with signatory record.
Visual evidence attached to critical clash issue records.
Gate review report with final status against acceptance criteria.
Clash test sets audited for scope and tolerance before first run.
Federated models verified current before each scheduled test run.
Classification rules applied uniformly across all test cycles.
Every open critical and major clash assigned to named appointment.
Closure requires re-run confirmation, not manual status update.
Design-intent acceptances signed by authorised representative.
Known false positives documented with test exclusion rules.
Cycle metrics reconciled against issue tracker status counts.
Construction issue assessment against documented acceptance criteria.
Tolerance changes versioned and communicated before next test run.
Critical clashes resolved by target date.
>= 95%
Open critical clashes at construction issue.
Zero unless accepted
Scheduled test runs completed on time.
100%
Closed clashes with re-run evidence.
100%
New clashes per cycle — trend should decrease through design development.
Decreasing trend
Days from clash identification to responsible appointment assignment.
<= 2 working days
Hard clashes are physical intersections where elements occupy the same space. Soft clashes are clearance violations where elements are too close without required separation. Workflow clashes concern construction sequence or maintenance access.
Tolerances are defined per system type and zone in the BIM execution plan. A 25 mm duct clearance requirement in a ceiling void differs from a 150 mm maintenance zone around switchgear.
No. Resolution occurs in authoring models. Navisworks re-run tests verify that source model updates have eliminated the geometric conflict.
Yes, when the conflict represents approved design intent. Accepted clashes require formal sign-off by the design lead or client representative and are recorded in the accepted clash register.
Counts vary by project complexity. The meaningful metric is trend — new clashes should decrease and critical closures increase through coordination cycles, not absolute count alone.
Let's plan the BIM scope, information requirements, delivery standards and coordination process in line with your project lifecycle.