Version 1.0.0-beta · in active testing · Report a bug
Coordination that follows the physics
The VDC Phase Tracker is a free tool for pre-construction coordination. It enforces the right sequence: loading before coordination, tier hierarchy before clash resolution, and a weekly commit cycle that holds every trade accountable.
Single HTML file. No install, no account, runs in any browser. Free. Open it in your browser to try it first.
An example of how I set up coordination
Most coordination tools track clashes. This one tracks the conditions that make clashes inevitable, and enforces the sequence of decisions that prevents rework.
It grew out of years of pre-construction coordination work, and a consistent frustration with the gap between how coordination software works and how coordination actually works. The loading gate, the tier hierarchy, and the gravity drainage model aren’t theoretical. They’re what separates projects that coordinate cleanly from ones that re-coordinate everything twice.
The same thinking shapes how I help teams set up VDC programs and coordination.
Built around how coordination actually works
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Two-phase model
Every area has a loading phase and a coordination phase. Coordination is locked until all disciplines have loaded their elements and a five-point gate is passed. Premature coordination is flagged and scored.
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Constraint tier hierarchy
T0 through T4, from absolute fixed conditions through primary MEP to secondary and architectural. The tracker enforces resolution order and highlights out-of-sequence coordination.
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Gravity drainage logic
T1A constraints model the full slope path at building scale before ceiling coordination begins. Roof drain leaders, stack locations, and below-slab inverts are tracked separately from structural and MEP.
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Weekly commit cycle
Trade updates are logged against specific constraints and attributed to contacts. At the end of the week, the VDC manager commits, freezing a permanent snapshot and generating a distribution email.
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Risk scoring
Every constraint carries a live risk score based on tier, confidence, status, gravity role, overdue penalty, and area density and criticality. Global and per-area scores trend over the life of the project.
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Navisworks integration
Export selection sets from Navisworks directly into area definitions. Bounding volumes, element counts, and inferred system types flow in automatically. A live bridge is available through a local WebSocket server.
Two phases, in order
- Loading phase
- Every discipline submits its elements at the required level of development. The VDC manager tracks per-discipline confidence and runs the five-point loading gate. Nothing here is about solving; it’s about confirming the problem is fully visible.
- Coordination phase
- Unlocked only after the loading gate is passed. Constraints are resolved in tier order: T1A gravity first, then structural, then primary MEP, then secondary. Coordination that starts before the gate passes is flagged as premature.
Why this mattersCoordination that starts before all disciplines are loaded produces solutions built against an incomplete picture. When the missing elements arrive, every resolved clash has to be re-checked. The loading gate prevents that rework, and makes it visible when a team is about to make that mistake.
Constraint tiers
| Tier | Category | Coordinate when |
|---|---|---|
| T0 | Absolute fixed: regulatory or legal | Before project design begins |
| T1 | Structural primary: EOR approval to change | Before any MEP routing |
| T1A | Gravity drainage: physics-constrained, building-height scope | Before any ceiling plenum coordination |
| T2 | Fixed program: owner decision to change | Before primary MEP |
| T3 | Primary MEP distribution: duct, pipe, and bus duct mains | Before secondary MEP |
| T4+ | Secondary MEP, branch work, devices, ceiling | Last |
Eight steps from kickoff to fab release
The tracker follows the natural sequence of a pre-construction coordination project. Each step builds on the one before.
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Set up the project registry
Add every trade and consultant with contact details. Define every building system: structural steel, drainage, HVAC mains, electrical, fire protection, low voltage, existing-to-remain. Assign each system to its owning trade and default tier. Done once, inherited by all areas.
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Define coordination areas
Create areas wherever systems compete: the mechanical room threshold, primary shafts, below-grade connections, main corridor intersections. Set density, criticality, sequence priority, and loading and coordination phase dates.
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Check which systems are present
Each area lists every registry system as a checklist. Checking one adds its owning trade as a discipline requirement and creates a placeholder constraint from the system template. Unchecked systems don’t affect scoring.
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Run the loading phase
Track discipline loading per area. As each trade confirms its elements are at the required LOD, mark it loaded and set a confidence level. When all five gate criteria are met, the VDC manager signs off and coordination unlocks.
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Coordinate in tier order
Work T1A constraints first, then T1 structural, T2 program, and T3 primary MEP. Hold T4 work until the tier above is resolved. Constraints move from open to active to resolved, and the risk score updates automatically.
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Run weekly meetings in Meeting mode
Areas display one at a time on a full-screen view, with discipline loading on the left and constraints with live clash counts on the right. Each trade confirms status in real time.
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Log and commit the week
Log each trade’s updates against specific constraints: status changes, confidence updates, loading confirmations, gate sign-offs. At the end of the week, commit. A permanent snapshot is frozen, a standalone week file is saved, and a formatted email report is generated.
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Release for fabrication in sequence
As areas complete coordination, the coordination gate is passed. Fab release packages are logged as T3 or T4 constraints with the trade as owner. The By Trade view confirms no trade is releasing for fab while upstream constraints are still open.
Free to use, always
No account, no install, no server. Every file runs in your browser, and your project data stays on your machine in an open, readable JSON format.
- vdc-phase-tracker.html The full application: all five views, the registry, the weekly cycle, and the Navisworks connector.
- vdc-guide.html The full guide: the two-phase model, tier hierarchy, gravity drainage logic, and workflow.
- vdc-default-project.vdcpt Starter project: 5 areas, 21 disciplines, 16 constraints, all dates empty. Open it in the tracker to begin.
No account. No expiry. Keep the files. Changelog · Report a bug
If the tracker saves you time on a project, consider supporting its development.
Want this approach on your next project?
Taking new engagements starting November 2026.