A 4D simulation plays the schedule on the 3D model, so each package colors as its work is planned to start and finish and the sequence of construction can be watched on the plant itself. It shows exactly what the dates in the register say.
The Schedule Drives the Model
The IWP or CWP register supplies planned and actual dates, and the simulation steps through them. On any date the model shows complete work in one color, work in progress in another and work not started in a third, with planned bars and actual progress on one timeline beneath the viewport. Scrub to a date and the plant assembles in construction order, concrete and steel first, then equipment and piping, amber while under construction and in its real color when complete. The model has to be conditioned first, with CWA, CWP and IWP attributes on every object, or there is nothing for the dates to drive.
Status Coloring Turns It Into a Readiness Picture
The same engine colors the model by other status fields. EWP status shows which areas have engineering issued and which are late. Material status shows what is at site and what is not. Fabrication status shows spools and steel moving through the shop. A construction manager walking the model this way sees next month's constraints as geometry, and a client review understands the sequence without reading a Gantt chart.
A Video the Site Team and the Client Can Watch
The simulation exports as a video. The frame is composed once, with the viewport, the Gantt, the skyline, the S-curve and the legend placed as the audience needs them, and rendered in the browser or on the server. A superintendent plays it in the morning meeting, and a client watches the month's plan in two minutes. openAWP's 4D simulations work this way, built on the IWP register's planned and actual dates, and the 3D model inside a Power BI report, described in 3D Model in Power BI, carries the same status coloring into the weekly report.
What It Does Not Do
A 4D simulation does not plan the work. The sequence comes from the path of construction, the CWP schedule and the IWP lookahead, and the simulation shows them. It does not replace the Level 3 schedule in Primavera P6, which stays the system of record for dates and logic. And it is only as honest as the dates behind it. A model colored green from planned dates nobody updated is a picture of a plan that no longer exists, which is why the simulation is tied to the register and re-run whenever the data moves. What BIM is on capital projects sets out the model's wider role.
AWPBI's BIM services condition the model and build the simulations on it, and the model, the register and the simulation templates stay with the client when the engagement ends.