Comparison and Renaissance of Classic Line-of-Balance and Linear Schedule Concepts for Construction Industry

Abstract

Line-of-Balance (LOB) is a useful analytical tool for repetitive activities in construction projects, which allows showing which crew is assigned to what repetitive work unit of an activity. LOB is closely related to the linear scheduling method, but possesses some challenges: It must be clarified how it counts, as previous studies displayed an apparent measurement gap at the origin, implicitly representing that LOB starts at the first unit finish. Slopes in linear scheduling and LOB are different, even though both portray a measure of progress of an activity. This paper therefore tracks evolution and current use of LOB versus linear schedules. Its contribution to the body of knowledge is threefold: First, based on a literature review, LOB is found to be rooted in Activity-on-Arrow (AOA) diagrams, which makes it event-centered, not progress-centered. Differences in representing the start and productivity between LOB and linear scheduling are reviewed and explained both mathematically and graphically. Second, different LOB concepts are extracted and assessed to facilitate comparing LOB from its original use in manufacturing against the limited application of its objective chart in the construction industry. Third, a mathematical formulation based on singularity functions is developed, which can model staggering, continuity, and interruptability scenarios. Fourth, the repetitive nature of LOB and LSM enables resource-specific equations that model the level of detail of individual crews performing individual tasks.