Task difficulty assessment: a contribution towards improved buildability through simplification

The assessment of buildability within the UK construction industry has typically been carried out on the basis of personal expertise, within which there may be many subjective considerations. This thesis examines the possibility of assessing buildability on the basis of objective criteria, and in an automated manner. A particular problem for buildability to address is identified as the UK construction industry's fragmented nature, particularly the separation between design process knowledge and construction process knowledge. The thesis identifies this separation as commencing during the Renaissance. The thesis examines a number of possible bases for the assessment of buildability, and concludes that task difficulty appears to be the most suitable basis to meet the objectives of the thesis. Various methods of assessing task difficulty in industries other than construction are evaluated, but none are found to be directly transferable to the assessment of difficulty within construction tasks. No pre-existing methods of assessing task difficulty within the construction industry were identified. The possibility of assessing buildability through an objective assessment of task difficulty measured in terms of operative skill represented within skill models is evaluated. Such skill models represent a new contribution to knowledge. The success of skill models is found to depend upon the application of general tolerance requirement theory, which supports the buildability attribute of tolerance requirements. Other buildability attributes are identified, but not examined in detail. The effect of various approaches to identifying and counting tolerance requirements on buildability assessment is considered and an algorithm is developed to guide the process. The research shows that objective assessment of buildability on the basis of tolerance requirements is possible, and that this can be carried out within a CAD environment at sketch design stage in an automated manner using a generic task approach to skill modelling.