An object-oriented knowledge-based systems approach to construction project control

Proper construction monitoring and control minimises overruns in time and cost, and degradation in construction quality. However, knowledge-based systems (KBSs), meant to improve management efficiency, have largely failed to make an impact in construction project monitoring and control. This failure can be attributed to some of these reasons: poor knowledge representation, improper handling of uncertainty and the use of old expert system shells which cannot handle the complex nature of construction project control problems. Meanwhile, the advent of object-orientation has brought added capabilities for KBSs to overcome some of these problems. This thesis is based on developing an object-oriented knowledge-based systems approach to decision support for construction project monitoring and control. To accomplish this work, the following major steps were taken. A taxonomy of construction project monitoring and control methods was undertaken. KBSs in construction project monitoring and control were reviewed and critiqued, and solutions to their shortcomings were proposed. A new risk management approach was developed that uses linguistic variables to cater for uncertainty and lays emphasis on treating risk interdependencies. Fuzzy logic, used for implementing the linguistic variables, is good for handling subjective information, and is a convenient bridge between the vagueness of human language and the discreteness of computer instructions. The risk management approach developed was employed for the development of an object-oriented knowledge-based system (KBS). Object-orientation enabled cross-fertilisation between object-oriented paradigms and rules and helped the KBS attain a high level of functionality. The KBS uses linguistic variables, implemented as a dynamic link library, for handling uncertainty. The KBS was linked by dynamic data exchange to a planning package. The planning package stores information on the tasks that make up the project. This information is used by the KBS to effect the control. The risk management process and the KBS developed were validated through a case study and visits to industry. The work done has made original contributions in both risk management and KBS development. First, it has developed a new risk management approach which is unique in using (i) fuzzy logic to model risk interdependencies, (ii) fuzzy mapping function to assess the impacts of risks, and (iii) a risk representation schema for representing risks, their impacts and responses. Second, by using object-orientation, handling uncertainty using linguistic variables and being linked to a planning package, the KBS developed, unlike previous systems, functions closer to practice where decisions are mostly made on the basis of incomplete information.