Organiational Management

This study aims to explore the impact of 3D CAD and BIM on estimating practices based on the notion that both paradigms, in varying degrees, improve the cost performance of projects compared to the use of conventional design tools such as 2D-CAD. The objectives are: (1) to explore the activities required to develop workable estimates in different estimating practice domains and represent them in the form of process models; (2) to establish the degree of association and reliability of the identified activities; (3) to compare 3D CAD and BIM estimating processes across different practice domains (using discriminant analysis); and (4) to suggest how the process models can be implemented and further strengthened for application development. The theoretical framework of the study was based on Kagioglou et al.’s (1999) process re-engineering model - to define the forms and goals of estimates in the different phases of the development of construction projects. Further review of literature shows there are several estimating methods that are applicable to the various project development stages, which are ontologically stratified across the various construction business domains. Consequently, different perspectives of estimating practice in construction businesses are developed from four business structure models viz. the MModel (representing client organizations), the DModel (representing contracting organizations), the FModel (representing consulting practices) and the NModel (representing specialist project delivery systems such as IPD). Mixed and plural research methodologies were used to explore the stages and activities that are involved in 3D CAD and BIM estimating. Firstly, products of four software development organizations were investigated to ascertain how the applications were used for 3D CAD and BIM estimating. Data were also explored from 5 presentations on 3D CAD and BIM estimating by the software development companies to 77 subject-experts who offered their views on estimators’ expectations of BIM applications. Secondly, participants, 17 in total, were sourced from the 4 business models indicated above to discuss their 3D CAD and BIM estimating processes. Data were captured through focus group sessions and individual interviews. The estimating themes for 3D CAD and BIM were garnered from the aforementioned qualitative data using a combination of direct observation, focus group discussions and interview sessions. Through these methods, the stages and activities involved in the preparation of estimates based on 3D CAD and BIM across the four business structure models were identified and rated. These ratings were statistically analysed to test whether the variables were sufficiently robust to be used to create process models, which the different practice domains can deploy to generate workable estimates with 3D CAD and BIM. The data were normally distributed and were analysed parametrically. First scoring factor analyses showed that the views of participants from DModel and FModel practices were highly correlated in both 3D CAD and BIM regimes. In addition, multiple comparisons using Fisher-Hayter and ANOVA procedures showed the key characteristics of the variations between how participants from the different practice domains viewed the importance of activities leading to estimating outcomes. Additionally, reliability tests (Cronbach’s Alpha) were used to measure the internal correlation of the estimating activities that were identified in both 3DCAD and BIM. In 3D CAD, 16 out of the 31 themes were discounted for lack of internal consistencies. The resultant process model has an Alpha value of 0.96. In BIM regime, analyses show the Alpha value to be 0.95, while only four themes (estimating activities) were discounted for lack of statistical consistencies. The themes retained after the reliability tests formed the centroid (group representative) process models for the 3D CAD and BIM estimating. However, the derived variables in the centroid models apply differently to the practice domains. Consequently, both ad-hoc and post-hoc data were analysed to determine the discrimination of the centroid models across the four practice domains. Implementation of the process models was also discussed. First, illustrations were made on system architectures for the process models. Second, indicative EXPRESS-G structures were provided to show how the process models can be advanced for implementation in the form of applications, training and for future research. Third, indicative integrated definition formats (IDEF0) were developed to illustrate how the outcomes of the process models can be strengthened with case-based control measures. This study has established that estimators still use conventional methods to estimate 3D CAD projects, and more than 50% of activities leading to estimate outcomes in this domain do not add value to estimating outcomes. This study also presented the key characteristics and enablers of opportunities for estimators in BIM. Recommendations were also drawn on how to develop change management models for dealing with operational issues when transiting from conventional practices to digital systems.