Case Studies of Using Flowline for Production Planning and Control

Abstract

Flowline, or Line-of-Balance, has recently gained attention in Lean Construction literature because of its capacity for facilitating control of production flow and planning of continuous work. In the broader technical literature, previous work has concentrated on the analytic properties of flowline, such as learning curves, and is generally silent on how the method should be used to improve productivity. This is because internationally the technique has received relatively little application. However, in Finland, flowline has been used as the principal scheduling method since 1980s. This paper takes a practical approach and describes the use of flowline based planning and control in two real case projects. One of the projects is a large residential construction project in Sydney, Australia. The other project is a Finnish retail park construction project. These pilot projects were done at the same time and the projects were able to learn from the experiences of the other. The cases highlight the differences between the Finnish way of planning a schedule with buffers between activities with synchronized production rates and the Australian way of driving a schedule with a tightly constrained CPM schedule. A methodology using flowline as a visual planning tool but using familiar CPM logic as the underlying engine was appropriate in the Australian case. In this methodology the objective is to improve site control by including information about location and to be able to plan continuous work for subcontractors and to visualize the effects of planning decisions. The result is much clearer communication to the trade contractors about the timing and location of their work, improved control systems and better work flow. The Finnish project team was already familiar with the basic use of flowline so the more advanced risk management based approach was used. The risk management based approach includes using quantities estimated by location as the starting point and optimizes the crews so that the risk of schedule disturbances is minimized. The planning happens on two levels: the master schedule has less detail and the task plans are detailed plans of individual tasks which are done by persons responsible for the work when all the necessary information about implementation is available. The results from the Finnish case include a methodology for effectively controlling production flow and how to include the subcontractors in the process. 109 Comparison of the two different strategies reveals important knowledge about the role of custom in scheduling, and reveals potential barriers to adopting innovative approaches.