Even with BIM becoming more prevalent, it’s not often that the same 3D model is used throughout a project — from estimating to the field. For decades, 2D was the industry standard and even with more projects moving to 3D, we still see a fair amount of re-work in shifting between 2D drawings and 3D models. When this happens, we lose the ability to visualize and the resulting re-work is time-consuming and opens up the potential for errors which, in essence, defeats the purpose of BIM.
A Shift in Perspective
In 2016, we were computer drafting our design drawings with AutoCAD. BIM was intriguing to our team, but we weren’t ready to make a commitment. It was during a design-build meeting on an industrial project that year when everything shifted. During a meeting to work with the project team on the design, we worked from a 3D model provided by the engineer. We didn’t open the plans once, yet the model gave me a really good understanding of the job. This was unexpected. I always thought that because we aren’t designers, the 3D model doesn’t hold a lot of value for our customers. But on this project I realized that the visual nature of BIM can help to ensure that crews in the field understand exactly what they're building. Most of the crews and project teams in this business are visual, so telling them how to build something is one thing but showing them is completely different. I walked away from that meeting ready to approach BIM with a different mindset.
Putting BIM to Work
With this new outlook, we started to look at all the places in our business where BIM could add value. We began exploring BIM by using Trimble’s BIM software, Tekla Structures, to automate formwork design which, at the time, was done with AutoCAD or by hand.
Our goal was more automatic and quickly designed formwork with enough detail to eliminate or reduce the 2D plans that we provided to crews in the field. For example, specifically showing the type of clamp and illustrating the reason behind it so the crew could understand it visually.
Using the pour and concrete geometry in the Tekla Structures model, along with interactive and automated tools, allow us to create realistic formwork models for planning and optimizing our formwork operations in far less time. Not only do we have 3D formwork models to share with the field crews, we also have detailed drawings that are created from the model by pour and a quantity take-off for the formwork needed to build the structure by pour.
We recently did a side-by-side comparison of a Tekla Structures model and 2D drawing. The goal was to get a basic sequence that we could make visual by importing into Tekla Structures. Modeling the entire structure in Tekla Structures, we broke it down into 80 pours that coincided with the engineer’s plans. We created a sequence for the most efficient way to carry out those pours across the five crews working on the project and were able to share a video sequence of which pour each crew would work on and when.
Showing that we had thought through the process and had a plan that was based on a constructible 3D model was powerful. In parallel, we carried out the same process on paper. We then put 2D sequence into a schedule and imported it into Tekla Structures. The visual sequencing showed us that there were errors in our 2D drawings. On paper we couldn’t see the problems in sequencing, where one pour should start after another. But with the 3D model, we could easily visualize the order in which pours needed to happen. In most cases, we will continue to use a 2D drawing to get a desired flow of concrete placements and then use Tekla to find and correct errors.
In the Field
With that success behind us, our goal was to push the 3D formwork models to crew supervisors for use in the field. Today, we create highly-detailed work packages for each crew’s daily assignments. Using Trimble’s collaboration platform, Trimble Connect, we provide crews in the field with a constructible 3D Tekla Structures model that they can spin around on their iPad and look at from any angle, directly from the job site. Sharing a model with as-built information that is truly constructible accelerates communication with the field crews, allows them to visualize the formwork and makes the entire process much more efficient.
Model-Based Estimating
We’ve recently explored using the 3D model to double check estimates. In today’s competitive market, estimators are required to work fast. It’s not unheard of for a number to be transposed or entered incorrectly. Recently, we bid on a project for a 6 MGD Wastewater Treatment Plant Expansion and the numbers seemed to be off, so we modeled portions of the project in Tekla Structures and exported them to a spreadsheet. This allowed us to compare the quantities and determine the accuracy of the estimate.
Occasionally, an owner will provide us with parameters for a project and ask us to provide a model-based estimate. In this case, we can quickly create a 3D model in Tekla Structures and use the cubic yards of concrete and square feet of forming and finishing to estimate the man hours of those units and determine a budget and schedule. If our bid is accepted, we have confidence that our estimates are correct because we use a constructible, data-rich model to determine accurate quantities. And, we can continue to use that same model once we begin the work.
Looking Forward
The tide is turning. For our business, staying relevant means innovating. We’re still exploring the many ways to incorporate BIM into our work but know for certain that it will continue to play a significant role in meeting fast-paced project delivery cycles and in streamlining our workflow, reducing inefficiencies. and encouraging collaboration across the project lifecycle.
