The architecture, engineering, and construction (AEC) industry has made huge strides in harnessing the power of building information modeling (BIM). The technology is particularly helpful with nontraditional project delivery, where collaboration between the design and construction teams starts as early as the schematic phases. This is a terrific competitive advantage for both parties but, unfortunately, tends to recreate information at every stage – thus negating BIM’s streamlining capabilities.
For example, contractors don’t need to model a wall if it’s already modeled by the designer; they only need to verify the information later on. American Concrete Institute Committee 131 – Building Information Modeling (ACI-131) is developing an Information Delivery Manual that will standardize how elements are handled. However, until it’s released contractors must devise their own approach to eliminating duplication and verifying information downstream.
Ours uses the designer’s model, saving us the time and effort of creating one from scratch. A base estimate is automatically created from the models, which load activities and their respective quantities, along with codes used throughout the company, into our estimating software. This data is transferred to our accounting system, aggregated at the end of construction, and embedded back into the models as historical data containing rates of production and unit costs.
This beginning-to-end process produced significant time savings on projects delivered over the last year.
Adding Intelligence to 3D Models
At a fundamental level, every construction activity is made of the same building blocks. If those building blocks are standardized, information can flow from one stage to another seamlessly. That opens the door to automation.
Like many technologies, the devil is in the details. Wrong data in is wrong data out. Most of the automation is in the data entry realm of the process, so the organization must have a common language and common protocol everyone follows. We divided the entire construction process into the various phases and determined the trigger point at every phase. Determining that trigger is key; it is what connects the information between the phases.
Any common piece of information that flows from preconstruction to operations through the various processes such as budgeting, scheduling, etc., could be a trigger point. We use bid item numbers tagged with our accounting cost codes to connect the information. We assign these to each element, which translates to a physical component of the structure in the real world, in the 3D model.
We then apply a checkbox to every structural element in the model, each containing possible construction activities for that particular element. We’ve developed a number of these checkboxes. For example, the checkbox for a suspended concrete deck:
- Truss table form system
- Hand-set form system
- Post-tension
- Place concrete with pumps
- Place concrete with crane
For a wall footing:
- Single-curtain rebar rack
- Double-curtain rebar rack
- Place concrete with pumps
- Place concrete direct
- Set/strip formwork
How This Facilitates Estimating
The checkboxes allow for constructability analyses by providing a set of possible activities that can happen for a component or entire building. Our team can pick and choose which one is applicable based on project design and logistics. In addition to single elements, they can group elements, such as columns, by floor, area, building, etc.
Once the estimate is converted to a budget in preconstruction, the 3D elements have the bid item numbers embedded and the cost codes are connected to them. Hence, when a lift drawing is printed, the 3D elements can also show all the cost codes associated with the scope shown, which helps to record production hours in the field much more easily. Field supervisors don’t need to assign cost codes to hours worked against a certain element because the BIM model is automatically assigned with the appropriate project cost codes once the budget has been created.
Requests for information (RFIs) and change orders can be shown visually in the 3D models overlaid on the old scope, so we can still derive quantities and price. This immensely helps owners understand the ramifications of a change in scope.
This is what a seamless flow of information looks like, and is just one of many examples that it can be used for. It allows the user to analyze the constructability of a project while working on the 3D model and, as a byproduct, automatically derives the quantities and standard codes for the assigned activities for the 3D elements.
All this information is stored in a standard format derived from the embedded information in the 3D elements, such as standard cost codes, bid categories, etc. This embedded information can be designed to match any existing company standards. In addition to adding intelligence to 3D models, this creates a common link which automates the data transfer among enterprise 3D BIM authoring, estimating, and accounting software.
Industry ForesightHow information is modeled in the design community has downstream effects for contractors. With the ability to derive quantities, specific details, and specifications, our processes will only get better over time. The real advantage with 3D models is the reduction in data duplication among the various stakeholders in a project. Our custom tools and processes take advantage of the enriched information and save time and money.
