CPM/LOB: New methodology to integrate CPM and line of balance

The line-of-balance technique (LOB) for planning and scheduling repetitive projects such as houses, high-rise buildings, precast concrete production, etc., has been used since the 1950s. It has provided unique and useful dimensions to users in perceiving when a project goes out of balance in addition to its essence of capitalizing on the economy of repetition. However, it is still not suitable enough for dealing with repetitive projects where the network of the typical unit is complex and has many branching paths. It is unwieldy in large projects, difficult to update or accelerate, and does not immediately give an accurate measure of the time progress of a project. The critical path method (CPM), on the other hand, is developed to an extent that it predominates in the industry. However, its use on repetitive projects is challenged by its inability to react promptly to the incident problem of changing the sequence of work on the typical units and to maintain work continuity for the working squads. This paper presents a new methodology, CPM/LOB, that adequately integrates the merits of CPM and LOB by attacking the novelty of using resource leveling and the float times calculated by CPM in the LOB. The virtue of the method lies in its invulnerability to changes in the sequence of work and to its ability to maintain work continuity for the working squads of the repetitive activities. It is based on the writers' field experience and extensions of previous researchers' work in the field that was prompted by the necessity.