In development — Beta Version 1.0.0-beta · Active testing in progress · View changelog · Report a bug v1.0.0-beta
Pre-construction BIM coordination

Coordination that follows
the physics.

A free tool for VDC teams that enforces the right sequence — loading before coordination, tier hierarchy before clash resolution, and a weekly commit cycle that holds every trade accountable.

Download the tracker Read the guide → Support development
Single HTML file · No install · No account · Runs in any browser · Free
Overview

Built around how coordination actually works

Most coordination tools track clashes. This one tracks the conditions that make clashes inevitable — and enforces the sequence of decisions that prevents rework.

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.
Constraint tier hierarchy
T0 through T4 — from absolute fixed conditions through primary MEP to secondary and architectural. The system enforces resolution order and highlights out-of-sequence coordination.
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.
Weekly commit cycle
Trade updates are logged against specific constraints and attributed to contacts. At end of week, the VDC manager commits — freezing a permanent snapshot and generating a distribution email.
Risk scoring
Every constraint carries a live risk score based on tier, confidence, status, gravity role, overdue penalty, and area density and criticality multipliers. Global and per-area scores trend over the project life.
Navisworks integration
Export selection sets from Navisworks directly into area definitions. Bounding volumes, element counts, and inferred system types flow in automatically. Live bridge available via local WebSocket server.
Phase 1
Loading phase

Every discipline submits their elements at the required level of development. The VDC manager tracks per-discipline confidence and runs the five-point loading gate. Nothing in this phase is about solving — it is about confirming the problem is fully visible.

Phase 2
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. Any coordination that starts before the gate passes is automatically flagged as premature.

Why this matters: Coordination that starts before all disciplines are loaded produces solutions built against an incomplete picture. When the missing elements arrive, every resolved clash must be re-checked. The loading gate exists to prevent that rework — and to make it visible when a team is about to make that mistake.

TierCategoryCoordinate when
T0Absolute fixed — regulatory / legalBefore project design begins
T1Structural primary — EOR approval to changeBefore any MEP routing
T1AGravity drainage — physics constrained, building-height scopeBefore any ceiling plenum coordination
T2Fixed program — owner decision to changeBefore primary MEP
T3Primary MEP distribution — duct, pipe, bus duct mainsBefore secondary MEP
T4+Secondary MEP, branch work, devices, ceilingLast
Workflow

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.

  1. Set up the project registry
    Go to the Registry tab. Add every trade and consultant with contact details. Define every building system — structural steel, drainage, HVAC mains, electrical, FP, LV, existing-to-remain. Assign each system to its owning trade and default tier. Done once, inherited by all areas.
  2. Define coordination areas
    Create areas for every location where systems compete — mechanical room threshold, primary shaft, below-grade connections, main corridor intersections. Set density, criticality, sequence priority, and loading and coordination phase dates.
  3. Check which systems are present
    Open each area. Every registry system appears as a checklist. Check the ones present — the owning trade is automatically added as a discipline requirement and a placeholder constraint is created from the system template. Unchecked systems contribute nothing to scoring.
  4. Run the loading phase
    Track discipline loading per area. As each trade confirms their elements are at the required LOD, mark them loaded and set confidence level. When all five gate criteria are met, the VDC manager signs off and coordination unlocks.
  5. Coordinate in tier order
    Work T1A constraints first, then T1 structural, then T2 program, then T3 primary MEP. Hold T4 work until tier above is resolved. Constraints move Open → Active → Resolved. Risk score updates automatically.
  6. Run weekly meetings in Meeting mode
    Switch to Meeting mode for the weekly session. Areas display sequentially on a full-screen view. Left panel shows discipline loading, right panel shows constraints with live clash count inputs. Each trade confirms status in real time.
  7. Log and commit the week
    In the Weekly tab, log each trade's updates against specific constraints — status changes, confidence updates, loading confirmations, gate sign-offs. At end of week, commit. A permanent snapshot is frozen, a standalone week file is saved, and a formatted email report is generated.
  8. 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.
Download

Free to use, always

No account, no install, no server. Every file runs directly in your browser. Your project data stays on your machine in an open, readable JSON format.

HTML
vdc-phase-tracker.html
The full application — all five views, registry, weekly cycle, Navisworks connector
 HTML
vdc-guide.html
Full narrative guide — the two-phase model, tier hierarchy, gravity drainage logic, workflow
 VDCPT
vdc-default-project.vdcpt
Starter project file — 5 areas, 21 disciplines, 16 constraints, all dates empty. Open in the tracker to begin.
Download everything
tracker · guide · starter project
No account. No expiry. Keep the files.
Download tracker Read the guide ♥  Support development
JT
John Tauchus
VDC Coordinator · johntauchus.com

This tool 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 are not theoretical — they are what separates projects that coordinate cleanly from ones that re-coordinate everything twice. If this saves you time on a project, consider supporting its continued development.