- Problem Recognition
THE Introduction of BIM process into Design and Constriction work flows provides both Owners and Contractors with many advantages however during the tender stage, an owner must decide between use of traditional design and documentation methods or investment in more detailed modeling (BIM) which requires highly specialized management systems and software.
2. Development of Feasible Alternatives
An owners tendering strategy is dependent upon a large number of factors. For this exercise we will consider typical Design-Bid-Construct scenario using either of the following methods;
Alternative 1 – Owner developed 2D design format with typical project information including detailed archi, Structure, and MEP drawings, BoQ, material/equipment specifications, site data, etc
Alternative 2-Fully developed 3D design and BIM model including co ordinated structural, architectual, MEP designs inclusive of materials and element specifications plus model generated BoQ, site data, etc
3. Development of the Outcomes
Typical attributes to be used in the comparison of the above alternatives are outlined below.
- Simplification of design process
- Reduced Cost to prepare Tender documentation
- Reduce time to prepare Tender documentation
- Accurate representation of Project scope and requirements
- Flexibility to evaluate possible design options during tender stage
- Reduce risk of variations from Contractor
Within this example, there are no monetary or time figures available for the evaluation the alternatives.The following Non compensatory models will be used as the method of comparison;
Perceived strengths and weaknesses of each alternative shall be used in the assessment. Some of the advantages BIM is considered to offer over traditional design and documentation processes include;
4. Selection Criteria
The alternative which is considered dominant will be considered as the preferred alternative however if a dominant alternative cannot be determined, a Lexicograph model based on a ranking of attributes will be used.
The ranking shall be based on the preferences / criteria listed in table 1 (Paired Comparison)
In the above example, the owners priorities are to minimise costs for the development of the Detailed design as well as ensuring that the information provided during tender is accurate and represents the project scope. Based on the rankings, second is the Owners desire to reduce risk of unknowns and variations from the Contractor.
5. Analysis and Comparison of the Alternatives
An Assessment of Dominance among alternatives is outlined in below table based on perceived advantages and disadvantages of BIM process.
A dominant alternative cannot be identified with BIM considered to be superior in only 4 of the 6 attributes.
Under the lexicograph model and the ranking of attributes traditional design processs are determined to
From the ranking of attributes, Cost to develop tender design and Accurate representation of Project scope / Owner requirements are considered priorities to the Owners tender process. This is followed by Owners priority for a reduction in risk of variations (due to poor scope definition).
Whilst tradition tender and 2D design process is considered better in achieving the clients objective of simplifying the design process, BIM can offer a more accurate representation of the project scope and owners requirements through 3D visualization as well as coordinated design process. Given both of these alternatives satisfy each of the top ranked priorities, final selection may be based upon secondary rankings such as reduction in risk of variation from Contractor due to poor scope definition.
6. Selection of the Preferred alternative
Alternative 2 (BIM Process) is considered the preferred alternative on results above.
Whilst the BIM model development process during tender stages is considered more complicated and costly (Attribute 1 & 2) with a heavy / early reliance upon specialized BIM management skills, BIM will greatly increase the chance of the Owners design and project objectives being satisfied through through better visualization of requirements. The Owners desire to reduce variations though poorly detailed or communication of Work scope is also more likely to be realised with a BIM process.
7. Performance Monitoring and Post evaluation of results
In order to truly evaluate the effectiveness of BIM during the tender stage, the following information would need to be established at the end of the project;
- Quantity / Value of variations claimed due to scope omission/errors
- Number NCR’s or rework required by contractor due to non conformance with Specification
- Compliance with Owners tender design
- Redesign costs and time lost due to changes
- What is Building information Modelling and what are its advantages and Disadvantages (Krigh Bachman) retrieved from www.quora.com
- The Benefits Of BIM For Structural Engineers (Venu Gopal) retrieved from www.leevenspark.com/2015/01/the-benefits-of-bim-for-structural.html
- 15 advantages of using BIM
- Sullivan, William G., Wicks, Elin M. & Koelling, C. Patrick. (2014). Engineering Economy 16th edition page 600 -607, England: Pearson Education Limited.