4D BIM for Construction

When to develop a 4D Schedule?

Posted by Ken Meding on Jul 7, 2015 3:30:00 PM

This question has been asked multiple times within companies that are new to the VDC / BIM methods. The solution may be simple to understand but challenging to implement.  It’s understood that the construction industry is not the fastest to accept new methods and strategies.  Why should we? We have been constructing major projects for years without using these methods. 

The answer presented here is:  from day one! From the very start of the schedule development process. 4D scheduling has the greatest value when it is utilized to help provide insight and clarity during the very first stages of the schedule development.    


Insight into the construction schedule is one of the greatest values earned from developing a 4D Schedule. We all understand that the cost-influence curve dictates that as the project progresses our influence to make major changes decreases and the cost of those changes increase, significantly.  A 4D Schedule provides valuable insight into the construction scheduled by reducing risk in terms of known-unknown schedule errors without a 4D Schedule.  These errors are often never caught until it’s too late.  Currently the industry is beginning to demand that risk management becomes the new “Safety,” a practice that the industry has focused on, successfully, for the past few decades.   Reducing risk in the schedule has always been a major undertaking; however, with the advent of 4D Scheduling, that undertaking has become less burdensome.  Developing a base-line schedule in 4D reduces risk by providing insight into schedule logic, the sequencing of major components, and providing a quick visual check.  Currently schedules are reviewed by pouring over multiple sheets of Ghant charts and tables, this method can take hours and days to complete.  Even then, the full scope of the schedule may not be understood.  A 4D Schedule provides a visual check in the 3D world where one has complete control of visual time.         

Another reason for developing a 4D Schedule from the very beginning is people.  As often attributed to a famous scheduler; “Something funny occurred when we were developing a 4D Schedule; people got involved, they wanted more schedule meetings.”  If the most valuable resource we have is our people, then why are we not fully utilizing them when we develop out schedules?  We may be using them to a certain degree, but surely we are not appropriating them to their fullest extent. 4D Schedules allow all team members to understand the plan and make errors and potential issues (those known-unknowns) blatantly obvious. 4D Schedules allow schedule meetings to become more productive. People get involved, they are no longer chained to the mountains of paper Ghant charts and tables, and are instead in front of the projection screen directing, coordinating, and building the schedule.  They are doing what makes them valuable.    

The last reason presented is solid communication. Only a 4D Schedule can provide the concept of the full construction schedule in the shortest time.  The visual schedule can provide a more solid communication tool then the paper Ghant charts for the intuitive nature of a 4D Schedule is simpler to understand.  A 4D Schedule provides a better sandbox environment to create the “What if” scenarios necessary to develop lean, risk reduced, and achievable projects in a widely communicable media.        

But what if the 3D model is not ready?  The 3D model will never be ready.  In fact there may not be a 3D model for months.  That should not stop the development of a 4D Schedule. If a schedule is being developed, chances are there are 2D drawings or the project is similar to another project that has a 3D model that could be salvaged.  The 2D drawings could be used to create the 3D model components that are required to express the content of the developing schedule.  The lack of a 3D model should never stop the creation of a 4D Schedule.  Doing the best with the information at hand is already what scheduling is during the first stages of development. 

4D Scheduling will provide insight into the process, allow all team members to fully and quickly understand the plan, and it will undoubtedly improve the quality of scheduling while providing clear visualization.

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