The BIM Process..... contractors guide

From a contractor’s perspective, the “Model Based” BIM process depends on whether the project is designed initially in 3D or if it is designed in 2D and later “converted” to 3D. This section outlines the process of using Building Information Models, using these two approaches:
1) 2D Conversions
2) 3D Designs



Each of the five parts of this section assumes that most of the project is being modeled
in an intelligent 3D design. As mentioned earlier, many contractors have found it simpler to start using partial models, for portions of the project scope or for specific trades such as structural steel or mechanical. The second part of this section addresses some of these partial uses of BIM. The last section addresses other considerations for contractors trying to understand the process of using BIM.
1. Comparison of a “2D Based” vs. a “Model Based” industry
2. Partial BIM Uses—What are these?
3. 2D Conversions
4. 3D Designs
5. Other Considerations

A special note about the “cost of BIM” which is addressed in each approach: The
out-of-pocket expense, even after spreading out the initial technology and training
investment, is generally believed to be much less than the cost benefits. Research
efforts are underway to prove this point, but until results are in, the biggest challenge is
aligning who is receiving the benefit versus who is paying the out-of-pocket expenses.
The delivery method, the contract type and the basis of reimbursement may dictate
how and to whom the cost benefits will flow.

this information should be a good place for a contractor just learning BIM to get started.

1. Comparison of a “2D Based” vs. a “Model Based” industry 

The traditional 2D Based design evolved from pencils, to Mylar, to overlay drafting, to the layers and levels seen in CAD programs. These long market-accepted “flat” media, the separate nature of the layers, and multiple design and consulting disciplines have contributed to the 2D, layered, disconnected process prevalent today.

2. Partial BIM Uses – What are these?

Most contractors are likely to start using BIM through “partial uses.” The list of partial uses of BIM seems almost infinite. For contractors already using BIM, the list seems to grow daily. For those getting started, the following list represents some of the more common “early” uses that most contractors experience in their experimentation with BIM:
a. Visualization
b. Scope Clarification
c. Partial Trade Coordination
d. Collision Detection/Avoidance
e. Design Validation
f. Construction Sequencing Planning/Phasing Plans/Logistics
g. Marketing Presentations
h. Options Analysis (see example: “Partial use: Value Engineering Analysis,” which shows Precast versus Brick)
i. Walk-through and Fly-through
j. Virtual Mock-Ups
k. Sight Line Studies

3. 2D Conversions

When will most designs be delivered in 3D? Most estimates range between fi ve
and ten years. In the meantime most projects that “use BIM” are designing in 2D
and “converting” to 3D.

a. What is a “2D Conversion”?

b. Typical Process—2D Conversion

c. How do I do a 2D Conversion?

d. How much does a 2D Conversion cost?

e. When and where to do a 2D Conversion?

f. What are the benefits of 2D Conversion?

4. 3D Designs

a. What is a “3D design”?

b. Typical Process—3D design

c. How do I use a 3D design?

d. How much does 3D design cost?

e. When and where to use a 3D design?

5. Other Considerations

a. Using Converted 2D versus 3D Designs

b. Linking the Model to the Schedule (“4D”)

c. Outsourcing or Building the Model In-house?

d. Upkeep of the model during design? During construction?

e. The Project Delivery Method/Lean Construction

f. Getting over the Wall?