The BIM Episodes: Episode 10
A construction project passes through multiple phases from inception to demolition. These phases are typically referred to as Project Lifecycle Phases (PLPs) and include pre-construction activities like programming, cost planning as well as post-construction activities like occupancy and facility maintenance. Lifecycle phases can be delineated in a few ways but I have personally adopted a simplified subdivision as follows:
Construction projects pass through three major lifecycle phases: Design [D], Construction [C] and Operations [O]. These phases are also subdivided into sub-phases (Table 1) which are in turn further subdivided into activities, sub-activities and tasks.
|Construction Phase|| |
|D1: conceptualisation, programming and cost planning|| |
C1: construction planning and construction detailing
O1: occupancy and operations
D2: architectural, structural and systems design
C2: construction, manufacturing and procurement
O2: asset management and facility maintenance
D3: analysis, detailing, coordination and specification
C3: commissioning, as-built and handover
O3: decommissioning and major re-programming
Table 1: Project Lifecycle Phases and sub-Phases
As an example of further subdivision, the Design phase [D] includes Architectural, Structural and Systems Design sub-phase [D1], which includes an Architectural Design activity [D1.1], which includes the Conceptualisation sub-activity [D1.1a] which lastly includes a 3D Modelling task [D1.1a.01]. The usefulness of these subdivisions will not be too evident in this blog post but just remember that BIM implementations can and will affect construction projects at Phase, Task and everything in between. For now we’ll just focus on the effects of BIM on Phases and I’ll discuss the effects of BIM on smaller lifecycle subdivisions in later posts.
BIM Stage 1: Object-Based Modelling
As a reminder, BIM implementation is initiated through the deployment of an ‘object-based 3D parametric software tool’ similar to ArchiCAD®, Revit®, Digital Project® and Tekla®. At Stage 1, users generate single-disciplinary models within either design [D], construction [C] or operation [O] – the three Project Lifecycle Phases. These models - like architectural design models [D] and duct fabrication models [C] - are primarily used to automate the generation and coordination of 2D documentation and 3D visualisations. Other deliverables of Stage 1 models include basic data exports (ex: door schedules, concrete quantities, FFE costs,...) and light-weight 3D models (ex: 3D DWF, 3D PDF, NWD, etc...) which have no modifiable parametric attributes. However, the ‘semantic’ nature of object-based models and their ‘hunger’ for early and detailed resolution of design and construction matters encourage ‘fast-tracking’ of Project Lifecycle Phases (Fig. 1).
Fig. 1. Project Lifecycle Phases at BIM Stage 1 – linear model
Figure 1 above depicts how object-based modelling encourages fast-tracking: when a project is still executed in a phased manner yet design and construction activities are overlapped to save time . That is, after achieving maturity within Stage 1 implementations, BIM players will acknowledge the benefits of engaging other design and construction players with similar modelling capabilities. Such acknowledgement and subsequent action will lead them to BIM Stage 2, model-based collaboration.
BIM Stage 2: Model-Based Collaboration
Having developed single-disciplinary modelling expertise through Stage 1 implementations, Stage 2 players actively collaborate with other disciplinary players. This may occur in many technological ways according to each player’s selection of BIM software tools.
Model-based collaboration can occur within one or between two Project Lifecycle Phases. Examples of this include the Design-Design interchange of architectural and structural models [DD], the Design-Construction interchange of structural and steel models [DC] and the Design-Operations interchange of architectural and facility maintenance models [DO]. Stage 2 maturity also alters the granularity of modelling performed at each lifecycle phase as higher-detail construction models move forward and replace (partially or fully) lower-detail design models (Fig. 2).
Fig. 2. Project Lifecycle Phases at BIM Stage 2 – linear model
Figure 2 above depicts how model-based collaboration is a factor in instigating fast-tracking and changing relative modelling intensity within each lifecycle phase. The overlap depicted is driven by construction players increasingly providing design-related services as part of their Stage 2 offerings and design players increasingly adding construction and procurement information into their design models. Also, changes in semantic richness across lifecycle phases occur as detailed construction and fabrication models (ex: steel detailing and duct fabrication models) partially replace the more generic upstream structural and mechanical design models.
BIM Stage 3: Network-Based Integration
In this stage semantically-rich integrated models are created, shared and maintained collaboratively across Project Lifecycle Phases. This integration can be achieved through model server technologies (using proprietary, open or non-proprietary formats), single / integrated / distributed / federated databases [1,3] and/or SaaS (Software as a Service) solutions . From a process perspective, synchronous interchange of model and document-based data cause project lifecycle phases to overlap extensively forming a phase-less process (Fig.3).
Fig. 3. Project Lifecycle Phases at BIM Stage 3 – linear model
Figure 3 above depicts how network-based integration causes ‘concurrent construction’: a term used when “all project activities are integrated and all aspects of design, construction, and operation are concurrently planned to maximize the value of objective functions while optimising constructability, operability and safety” .
In summary, object-based modelling will first blur the lines separating different project lifecycle phases. As model-based collaboration takes hold, lifecycle players start moving into each other’s territory. Finally, as network-based integration becomes the norm, design, construction and operations overlap extensively if not totally.
Note on terms used within Figures:
- A BIM data exchange is when a BIM player exports or imports data that is neither structured nor computable. A typical example of data exchange is the export of 2D CAD drawings out of 3D object-based models resulting in significant loss of geometric and semantic data.
- A BIM data interchange (or interoperable exchange) is when a BIM player exports and imports data that is structured and computable by another application. Interchanges assume ‘adequate interoperability’ between the sender and receiver systems.
 Bentley, Does the Building Industry Really Need to Start Over - A Response from Bentley to Autodesk's BIM-Revit Proposal for the Future, http://www.laiserin.com/features/bim/bentley_bim_whitepaper.pdf, last accessed July 12, 2008
 A. Jaafari, Concurrent Construction and Life Cycle Project Management, Journal of Construction Engineering and Management 123 (4) (1997) 427-436.
 J. Liaserin, Building Information Modeling - The Great Debate, http://www.laiserin.com/features/bim/index.php, last accessed July 12, 2008
 P. Wilkinson, SaaS-based BIM, http://www.extranetevolution.com/extranet_evolution/2008/04/saas-based-bim.html, last accessed July 12, 2008