Abstract
1. Introduction
Although PERT/CPM method is recognized as an inevitable method for planning and scheduling in building construction projects, it has been applied to less construction projects as a planning and scheduling method, as it is not suitable for repetitive activities such as multi-floor buildings and large apartment houses with many dwellings. The authors proposed a new graphical representation which is based on the conventional network diagram and scheduling method for a building project with repetitive activities.
2. Previous Research Works
The authors reviewed the previous works, and pointed out that many research works on planning and scheduling for repetitive activities have been done, but that those research works modeled the repetitive activities using non-network diagrams. Furthermore, there has been no research work which has established the planning and scheduling method using network diagrams for repetitive activities.
3. Basic Concept of Network Diagram and Scheduling Method for Repetitive Activities
The authors proposed the network diagram which shows only the precedence relations among activities in common work zones. And the authors defined those relations in the table of activity data as well as in the table of work zone data. Moreover, the authors introduced the concept of “work tickets” as a work instruction for each work zone.
To calculate the schedule dates, the authors utilized the concept of the flow of work tickets along the precedence arrows in network diagrams. The time when the work ticket has entered into an activity and the time when it has left from the activity could correspond respectively to the start date and finish date.
4. Network Diagram and Scheduling Method for Sophisticated Repetitive Activities
To apply this method to sophisticated projects with repetitive activities, the authors developed the algorisms to handle the flow of “work tickets” in network diagrams so that the following conditions could be included in repetitive activities.
(1)Work zones which include activities of different contents and different durations
(2)Precedence relations between activities in different work zones
(3)Precedence relations to activities from activities in several work zones
(4)Restrictions which prohibit more than two simultaneous activities in a specific area
5. Verification of the Usefulness of the Scheduling Method
The authors applied this method to plan and schedule a four-story apartment house with 32 dwellings, so as to verify the usefulness to represent the sophisticated precedence relations among many work zones by using network diagrams and to calculate the earliest date and the latest date of each activity in the construction project. As the result of the verification, the authors successfully represented the repetitive activities as network diagrams, and correctly calculated the schedule date of each activity.
6. Conclusion
The authors summarized the feasible conditions of repetitive activities to which the method in this paper is able to be applied, and clarified this method would become more important as a planning and scheduling method, because the building construction project are required to be more efficient by applying repetitive activities in the project.
