Vico Guest Blogger Series

There Is No “Easy Button” for Quantity Takeoff in 5D BIM

Posted by Holly Allison on Mon, Apr 26, 2010 @ 12:47 PM

 

We all love the “easy button” commercials from Staples Office Supply Stores. Wouldn’t it be great if we could really just push a button when the copier is jammed, when we’re out of paper, or out of ink cartridges just as we’re getting ready to print ten copies of an important proposal!

 

That “easy button” thinking has made its way to virtual construction and 5D BIM.  Especially when we’re in the university classroom, some students believe that “hitting the button” inside Vico Office Takeoff Manager means that it will spit out a precise itemization of Takeoff Items and their Quantities. Perhaps this thinking also spills out into commercial construction where we see a significant amount of push-back to BIM from estimators and schedulers.

 

Vico Office is the first BIM-neutral platform that analyzes, organizes, synthesizes, and augments ArchiCAD, Revit, and Tekla files. The first step in this process is a comprehensive quantity takeoff which results in construction-caliber quantities. But it’s not as simple as a button.

 

With Vico Office, the quantity takeoff algorithm looks at each piece of geometry within the 3D BIM, calculates their properties (such as surface area, volume, etc.). The model geometry analysis algorithms can even determine the sides of the elements (for example "top of slab") and use the boundaries to calculate quantities such as "net surface area. " This type of analysis is much more intuitive than simply counting windows and doors, floors, ceilings, and walls, and produces a much more detailed quantity takeoff.

 

We are working to enhance the algorithms with each release so that all polygons in a model will be automatically assigned.  For example, each wall should contain a reference line which Vico Office uses to automate the quantity calculation.  If there is a problem with this line, it will trigger a warning in Vico Office that this calculation should be checked.  So reference lines (or more often than not, a lack of reference lines) can impede a proper polygon assignment and calculation.

 

Vico Office assumes that users will validate the Takeoff Items and Takeoff Quantity assignments and use the painting tool to correct issues. The algorithm and Takeoff Item creation options are designed to greatly reduce the need for manual painting.  The algorithms are not designed to eliminate the need for validation and we anticipate some corrections will always be required, especially on sloped, organic, or non rectilinear objects in the model or objects missing required meta data like reference lines. On every release, we’ll continue to increase the algorithm’s ability to deal with problematic conditions.


 

Caption: It’s important to recognize that the estimator and scheduler play a vital role in correctly assigning quantities. After reviewing the automatic assignment of polygons from the Vico Office Takeoff Manager algorithm, the estimator or scheduler can use the model to identify and correct any discrepancies.  This image illustrates the Paint Tool – a way to manually add elements in the model to a quantity takeoff item.

 

This further highlights one of the many benefits of model-based cost planning and scheduling.  Users can quickly toggle back and forth between their familiar spreadsheet view and a color-coded model.  If an element is not properly color-coded in the model, it is not properly quantified for the estimate and schedule.  By selecting a Takeoff Item in the Takeoff Manager view, the user can visually identify which 3D elements are assigned to the specific Takeoff Item and use the Paint Tool to add/remove 3D elements from it.

 

We wish there was an “easy button” to automatically extract construction-caliber quantities from the model - and we are working towards that end goal.  But the painting tool allows modelers, estimators, and schedulers to work around the current limitations of modeling and get to a more precise quantity count – and construction-caliber quantities in turn drive more precise model-based schedules and model-based estimates.

 

Vico has several webinars and papers to help you learn more about construction-caliber quantities to power your schedules and estimates.  We also offer a step-by-step guide to our 5D virtual construction workflow with video tutorials. These videos are just 2-5 minutes in length, but illustrate how to use a particular piece of functionality. You can access the video library index and view just what you need, or download the complete set of training videos.

 

Paper: Construction-Caliber Quantities
FAQs: Model-Based Cost Planning with Vico Office

Webinar: BIM-Based Estimating Fundamentals
Webinar:
The 5D Virtual Construction Workflow
Webinar:
Connecting the Conceptual Estimate to the Model Progression Specification

 

Tags: quantity takeoff, model-based schedules, model-based estimates, 5D BIM, Takeoff Manager