Enthusiasts of building information modeling have developed a standard specification that they say will help eliminate poor communication and misunderstandings within project teams using BIM. The 132-page document, coming out this summer, will offer users a common language for determining the specific content of design, construction and fabrication BIMs.
The 2013 Level of Development Specification, which is being formulated by the Associated General Contractors (AGC) BIM Forum, will be available free of charge. It is intended as an attachment to any contract as an aid for practitioners to specify and articulate with a "high level of clarity" the content and reliability of BIMs at various stages of design and construction, says the LOD spec.
"The overarching goal is to enhance the predictability of outcome while reducing the disappointment of unmet expectations," says Ronald F. Dellaria, chief compliance officer for architect-engineer and design-builder Astorino, Pittsburgh. Dellaria, a member of the all-volunteer LOD Working Group, is the inspiration behind the spec.
Another goal is to encourage design firms to make their models a contract document. "This is our aspiration," says architect Jan Reinhardt, a principal of ADEPT Project Delivery, Pittsburgh, and co-chairman of the 20-person LOD Working Group, made up of designers and contractors.
The spec is designed to drive efficiencies into the BIM process and remove uncertainty by enabling teams to specify a deliverable against a universal standard. It should make the BIM process more efficient by communicating specific expectations of all team members, which, in turn, should reduce over-modeling or under-modeling, say its developers.
The document also will enable model producers and users to check against standard, agreed-upon requirements and definitions, says Reinhardt.
Since 2008, most teams have used the American Institute of Architects E202-2008 BIM Protocol document for guidance. An updated AIA E202, renamed G202-2013, is coming out next month.
E202 lays out responsibilities for authoring each element of the model at each project phase, according to AIA. It also defines the extent to which downstream users, such as contractors and fabricators, can use and rely on the model for scheduling, pricing, fabricating and constructing. The document assigns model management to a specific party by project phase and clarifies who owns the model and who has the right to use it.
E202 contains five LODs. LOD 100 corresponds to conceptual design; 200, design development; and 300, contract documents. LOD 400 is for a model with fabrication levels of detail. LOD 500 is for a model with as-built levels of detail.
Though E202 works relatively well, it is too vague and the LOD descriptions are weak, say users. Also, E202 doesn't specifically address element reliability.