In a BIM coordination meeting, nobody opens Revit. They open Navisworks, federate the architecture, structure and MEP models from three different firms onto one screen, and look at hundreds of places where ducts run through beams. For anyone new to BIM, the first question is: "what is Navisworks, and why not just use Revit?" It is a fair question, and the answer goes to the heart of BIM coordination.
This article answers four questions. Why does reviewing models need a tool of its own? What is clash detection, and what does one missed clash actually cost? What does 4D simulation give you? And finally: who on a project team needs Navisworks, and do you have to know Revit before learning it?
Why model review needs its own tool
Navisworks is Autodesk software for federating, reviewing, checking and simulating models from many sources — not for authoring them. It reads many formats directly: Revit, AutoCAD, MicroStation, SketchUp, IFC, point clouds from laser scanners. Tekla and ArchiCAD are handled through the NWC exporter built into those tools, or via IFC. Everything then combines into a single, compact file.
Three reasons it exists alongside Revit:
Models come from many tools. Architecture in Revit, steel in Tekla, infrastructure in Civil 3D, equipment delivered as IFC, the neutral format used to exchange models between different tools. Revit cannot open them all; Navisworks can. But federating them does not guarantee they line up. Models only sit in the right place when the disciplines agreed a shared coordinate system up front. If they did not, whoever federates has to correct position and units by hand, and that is usually the slowest part of the first federation session.
The federated model is heavy. On a high-rise, each discipline model runs to hundreds of megabytes; federate them inside Revit and the machine gives up. Navisworks converts everything to a minimal format — geometry and properties only, no editability — so a multi-gigabyte federated model still spins on a laptop.
The people reviewing are not the people modelling. Clients, supervisors, site engineers and subcontractors need to view, measure, section and comment — but must not, and need not, edit. Navisworks lets them do exactly that without any risk to the source models.
In short, if you ask what Navisworks is compared with Revit: Revit creates, Navisworks checks and communicates. Two different jobs, two different tools — and BIM coordination people live in the second one. What is BIM? places both in the wider BIM process.
Clash detection: what one missed clash costs
Clash detection is Navisworks' best-known feature, in a tool called Clash Detective. You pick two sets of objects (say, ducts and beams) and set a rule — touching, or closer than 50 mm. The software lists every violating pair, with an image, a location and a resolution status.
That list can run to hundreds of rows, and every row is money. Here is a simple example.
A pipe runs straight through the position of a concrete beam. Nobody spots it on paper, because the pipe is on an MEP sheet and the beam is on a structural sheet. The two are rarely overlaid, and overlaying them by hand still misses things.
The clash only surfaces when the fitters reach that point. By then the beam has been cast. Two options remain, and both are expensive.
The first is to break out the concrete so the pipe can pass through the beam. But cutting into a beam means cutting into load-bearing structure, so it has to be re-analysed and strengthened. The second is to reroute the whole pipe run, which drags the ceiling, the lighting layout and part of the documentation with it.
A single clash of this kind typically costs hundreds of millions of dong. If it hits a critical member, or halts work across a zone, the figure runs into billions.
With Navisworks, it all looks different. The clash appears during design, before anything is built. Two engineers spend about an hour choosing the fix. The cost on site is zero.
A typical high-rise shows hundreds to thousands of clashes on the first run. Most of them, of course, are a matter of shifting a pipe a few centimetres on the drawing and cost almost nothing. Only a few land in the expensive situation above. But added up, the total dwarfs the cost of doing BIM. This is why clash detection is the first BIM benefit clients notice.
What the software does not do for you: classify and decide. Among the hundreds of clashes in one run, some are real, some come from modelling errors, some are acceptable (a conduit passing through a masonry wall). The coordinator filters them, assigns owners and tracks each to closure — the daily work of a BIM Coordinator.
4D simulation
"4D" is the 3D model plus time. In Navisworks, the TimeLiner tool links each group of model objects to a task in the programme (imported from Microsoft Project, Primavera or a CSV file). Then it runs the simulation: the day the foundations finish, the day level 5 columns pour, the day the facade glazing goes on.
Three things a 4D simulation does that a bar chart cannot:
- Expose impossible sequencing. The simulation shows level 6 being poured while level 5 formwork is still up, or two crews in the same zone on the same day. On a Gantt chart, those two lines sit forty rows apart and nobody notices.
- Test the construction method. Model the tower crane, scaffolding, haul roads and laydown areas in an authoring tool, then federate them in as one more discipline. Run the simulation and watch whether the crane's reach covers the area it has to serve, and which route the concrete trucks take while zone A is being excavated.
- Explain the programme to people who do not read programmes. Clients, management boards and subcontractors grasp a two-minute animation faster than a 400-line schedule. Many tenders use 4D for exactly this.
For 4D to be useful, the programme must be detailed enough and the model must be split the way the programme splits — by storey, by zone, by pour. Scheduling in MS Project is the upstream skill — our article on what MS Project is walks through seven steps to a usable programme. Navisworks connects that programme to the model. For complex sites that need deeper simulation still, there is dedicated 4D software — What is Synchro 4D? compares it directly with TimeLiner.
Who on a project team uses Navisworks
First, three editions exist, because each role uses a different one. Navisworks Manage is the full edition, with both Clash Detective and TimeLiner — the coordinator's edition. Navisworks Simulate has TimeLiner for 4D but no clash detection. Navisworks Freedom is the free viewer: it cannot open native files such as Revit or AutoCAD, only files already exported to NWD or DWF, but it does display clash results, programme simulations and comments already saved inside them. Freedom is read-only, though: it cannot add comments or redlines of its own. When a job advert says "Navisworks Manage", they are hiring for coordination.
| Role | Uses Navisworks to | Level needed |
|---|---|---|
| BIM Coordinator | Federate models, run clash detection, classify and track clashes, prepare coordination meetings | Fluent — this is the main tool |
| BIM Manager | Review reports, check federation quality, present to the client | Confident use, no deep operation |
| Planner, site manager | 4D simulation, method checking, planned-versus-actual | TimeLiner plus model review |
| Site engineer, supervisor | View, measure, section and comment on site | Commenting needs a paid edition; Freedom is enough just to view |
| Client, project management unit | Review the model, watch simulations and saved comments | Viewing only — Freedom is enough |
| Modeller (Revit, Tekla) | Review assigned clashes, then fix in the authoring tool | Reading clash reports |
Do you need Revit before learning Navisworks
The answer is not required, but recommended.
Navisworks itself is easy to learn: federating, viewing, measuring, sectioning, clash detection, 4D — all operations, learnable in a few sessions. The Institute's 6-session Navisworks Manage course covers the full circuit: getting started, model management, visualisation and animation, 4D simulation with TimeLiner, clash detection with Clash Detective, then reporting and coordination. People who have never used Revit keep up fine.
But the value of a Navisworks user lies in understanding what they are looking at: is this clash real or a modelling error; can this duct move; can this beam take an opening. Answering that takes knowing how models are built (Revit, Tekla) and how buildings are built. Which is why the common path at the Institute runs: model in one discipline → Navisworks → BIM Coordinator. The Revit learning path for beginners places Navisworks at stage three.
One group is the exception: the people on site. Site managers, planners, site engineers and supervisors need to read models and work with the programme, but they do not model. For them, going straight to Navisworks makes sense — they already understand construction; only the tool is missing. The trade-off is that when a clash looks like a modelling error, they still have to ask the modeller. So this group fits reading and responding better than coordinating.
Frequently asked questions
What is Navisworks in one sentence?
Software that federates models from many tools and formats into one place for viewing, measuring, clash detection and programme simulation — not for authoring models.
Can Navisworks create or edit models?
No. It only federates, reviews, checks and simulates. Fixes are made in the authoring tool (Revit, Tekla…) and then refreshed into Navisworks.
Revit has clash checking too — why Navisworks?
Revit's Interference Check works only within a Revit file and its linked models, has no clearance rules, no status tracking, and slows down on large models. Fine for checking within one discipline; whole-project, multi-format coordination needs Navisworks.
Does 4D simulation require MS Project?
Not strictly; TimeLiner imports from Microsoft Project, Primavera, CSV files or manual entry. But a programme built in MS Project connects fastest and updates most easily.
How long does Navisworks take to learn?
The operations: six sessions. Classifying clashes correctly and running a coordination meeting: a few real projects with someone guiding you.
Are there alternatives to Navisworks?
Yes — Solibri, BIMcollab, Trimble Connect, and CDE platforms with built-in clash checking. In Vietnam, Navisworks remains the most common because it ships with the Autodesk ecosystem; the concepts transfer to every tool.