Construction
BIM Continued
So How Does it Work?
Like much new technology we have today, we’ve put the cart before the horse. This has led to learning experiences that have helped mold the BIM process. Some projects dove into creating 3D models before any input was provided from subcontractors. Designers who started with a 3D model, and then afterwards sought out the input of contractors have been sorely rewarded. Hundreds of designs and revisions have been created, deleted and replaced upon receipt of new information.
Some problems are rooted in contractors’ everlasting fear of being held accountable for dimensions, etc. As a result, trades will create designs separately and then try to come together later on. This results in a large amount of rework. Shown below is a project that opted for an interesting partnership to keep all parties accountable and on the same team, which lifted the burden of this CYA type of attitude.
Now designers are taking design back to the drawing board – literally. They’ve got giant whiteboards with sticky notes littered across to represent order, sequence, issues, etc. This seems to be the best approach – before anyone creates any models, all parties representing major MEP and structural trades collaborate on a plan.
Different Approaches
Still, there are some projects that only partially use BIM – for MEP and structural trades only. Early on, trades can collaborate with one model, or more commonly, create their own in their respective programs and deal with compatibility issues from one program to another. LAUSD’s Central Learning Center #1 used this approach with their mechanical, electrical and plumbing trades, coordinating from the underground all the way through to the roof.
One innovative project, the Sutter Medical Center Replacement Hospital, used a large partnership – between ten parties – to guarantee success of the project. They were held to the unconventional method of Integrated Project Delivery; also contractors could only make a profit if the project came in below cost. The owner gave a challenge to reduce waste and turn the building over in two-thirds the time with the help of BIM. As of early May 2009, the project was looking at about 86% of the total costs. Final results have yet to be determined.
Cost of BIM
Because of the costs involved, for a project to successfully use BIM from beginning to start, they must bid the project to include additional costs of BIM. What costs are involved? Costs related to man hours spent coordinating early on, licensing fees. However, any contractor will agree, the up-front costs of BIM are really an investment when compared to dealing with problems in the field with man hours and schedule on the line.
Similar to the LEED Process, for a project to be fully coordinated using BIM, time needs to be invested early on. Consultants, Big Chiefs, the big-headed must all be present at the meetings to ensure the necessary coordination is taking place.
In ENR the May 4 issue, two dimensional drawings were provided to a team to study and come up with coordination issues. These drawings were also given to a team to review using BIM methods. Guess how well the computer program outperformed the human? The human team recognized 6 constructibility issues and 1 conflict. The computer shot the human team out of the water: 257 constructibility issues and 7,213 conflicts! Just imagine if each of these conflicts created an hour of delay on a project (this is an extremely conservative estimate). 7,213 conflicts; That’s about two years of added man labor spent on dealing with these issues alone – and that’s a conservative estimate. So consider BIM to have these similar savings opportunities – not guaranteed, but a great bait to tackle most change order? issues.
