Quality Driven Scheduling in Construction

Despite the enormous research effort that has been made in the last fifty years, the goal of construction scheduling quality seems still a long way far. This dissertation has the aim of contributing to the understanding of the quality of construction scheduling, and three issues have been chosen: schedule quality; quality and project control; scheduling approaches for construction. The goal of the whole research work is to study quality in scheduling and project controlling, and to propose some possible research lines to better understand the needed quality for the planning, scheduling, and controlling approaches in construction projects, i.e. quality driven scheduling. Starting from the development of the Critical Path Method (CPM), PERT and Precedence Diagramming, until the recent Location-Based Planning, project scheduling has been developing and improving continuously. However, construction project scheduling systems are still considered to miss the goal of increasing project control efficiency. Project Scheduling is, indeed, one of the basic tools of construction project management, and the success of a project partially depends on having a high quality schedule that defines when each activity will occur and with which duration, and its logic links with other activities and their sequences. Moreover, construction productivity is considered to be improved through scheduling as it can manage different problems such as process productivity, coordination and safety, and connections between systems and processes. Quality of construction scheduling has been object of research in a rather limited manner, and the need of recommended schedule development practices for quality assurance of scheduling processes and deliverables still exists. Therefore, the research work is based upon three main research questions: a) what is schedule quality? b) what does scheduling produce in terms of quality? c) can the activity network schedule model be process-oriented and quality driven? The gained results propose the following regarding to the research questions. a) What is schedule quality? Schedule quality is the fulfilment of many schedule requirements, with the aim of satisfying the needs of work structuring of construction process and of scheduling mechanics. A method of understanding and measuring schedule quality in construction, termed “Schedule Health Assessment” is proposed. The Schedule Health Assessment method also has the aim of guiding the project scheduler in the schedule development process. b) What does scheduling produce in terms of quality? Project schedule is the basis for project control, mostly addressing time and progress of activities, and costs, while quality control is usually separated. Although, these three project objectives are interdependent, and process and product quality management should be fully included in project control. Quality control should be integrated in the project schedule through a “Quality Breakdown Structure”. c) Can the activity network schedule model be process-oriented and quality driven? Activity network creates logic of work structuring. A process-oriented scheduling method for construction has to deal with resources, workflow and spaces. The proposed method, termed Repetitive Networking Technique (REPNET), creates a quality driven construction-oriented schedule model by plotting network logic on resource-space charts and on flowlines. The research results suggest the implementation of these three approaches in the project scheduling of a construction project can improve the quality driven scheduling of the project, meaning the implementation of a good quality schedule, the integration in project control processes of the delivered quality and the process-oriented scheduling.