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Asking “What If” With The 4D BIM Sequencing Project Model

Posted by Patrick Krzyzosiak on Thu, Feb 25, 2016 @ 16:02 PM
Patrick Krzyzosiak
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“What if?” This tends to be the reoccurring question each project team faces when working with a 4D BIM construction-sequencing model. Model-based sequencing links model elements to schedule activities to develop a construction-sequencing plan. 5D model-based estimating adds in the element of cost to the 3D BIM model. The construction sequencing method is an invaluable resource for developing the project plan for the activity sequence and logistical requirements on an active construction site, or phased occupancy of a renovation, retrofit, addition.


Simulation: Construction Sequencing and Phasing

4D construction sequencing occurs just after VDC building coordination and constructability reviews and concurrently with 5D model-based cost estimation. Early on in the project, a project team discusses the use and purpose of using 4D model-based scheduling. In the building information modeling process, the design data is categorized and grouped using BIM software tools; all project activities are clearly identified. An overview of these activities is prepared. Generally speaking, visualization or simulation of construction sequencing is used to strategize a building’s overall construction.

Construction sequencing provides critical information for all stakeholders. For example, owners are very interested in knowing whether a project change could result in an earlier completion date. A project manager and/or superintendent may be interested in finding opportunities for increasing construction productivity like factoring in just-in-time material delivery and fine-tuning activity durations. This practice allows the team to tweak the conditions then run simulations to either substantiate or repudiate the feasibility of the proposed construction sequencing and phasing plan.

While owners are dazzled with visualizing a project’s construction simulation, the construction team is absorbed in managing the activities (critical path) to make sure the project stays on schedule and on budget. Large construction sites have multiple activities going on simultaneously. If not carefully watched, some of these activities could burn through a project budget if not identified. Early 4D model-based scheduling helps to identify areas with high burn rate potential. By loading resources (labor, material, equipment, etc.) to each linked activity, you can easily take corrective action. A project handled in this planned manner can save time and ensures the project meets its scheduled milestones.


Schedule and budget control: Monitoring schedule activity performance

The following lists the many benefits and results of 4D construction sequencing.


  • Illustrates the project’s spatial complexities.
  • Allows the team to predict and measure results in “what if” scenarios and simulations.
  • Lets stakeholders thoroughly understand how the schedule is prepared and how the process will be executed.
  • Provides project stakeholders with critical information needed for planning and conducting analysis.
  • Provides a clearer picture of the phased project schedule, illustrating the critical path of the project.
  • Allows for dynamic occupancy phasing plans offering multiple options and solutions to space conflicts.
  • Can incorporate manpower, equipment, and material resource planning via BIM model allowing for a more accurate project schedule and cost estimate.
  • Identifies rate of productivity.
  • Identifies potential space and workspace conflicts allowing issues to be resolved ahead before construction starts.
  • Identifies schedule, sequencing and phasing issues.
  • Identifies potential safety hazards
  • Analyze and validate safety measures.


  • A more constructible and manageable project.
  • Allows for greater analysis prior to construction.
  • Improved accuracy of the project schedule and phased occupancy planning.
  • Improved management of resources and project costs.
  • Eased material procurement and management.
  • Increased productivity and decreased waste on job site – a leaner jobsite.
  • Creates a construction environment that achieves a higher level of safety.

Have you engaged in 4D BIM sequencing? What was your experience? Please share your story with us in the comments section!


Topics: Sequencing and Phasing, Virtual Design and Construction (VDC), BIM, 4D Sequencing