ANALYSING THE IMPACT OF CONSTRUCTION FLOW ON PRODUCTIVITY

Construction is one of the least productive industries. A significant reason for this is not viewing the construction process as a combination of flows, i.e. continuous streams of workers, materials or equipment. This paper aims to improve our understanding of construction flow by demonstrating how it can be quantified and how its impacts on productivity can be measured. We discuss two main types of flow: 1) process/location flow, representing the flow of activities performed at a single location and 2) operations/trade flow, representing the activities performed by a single trade through different locations. Based on the literature, we develop a set of metrics for each type of flow. Then, we measure their influence on productivity by using data from four buildings' superstructure work packages. The process flow is compared with the productivity of individual locations, and the operations flow is compared with the productivity of separate crews. The results show that the excess work-in-progress time between successive crews and the mean and variability of production rates for different crews at each location (process flow metrics) can explain 72% of the variation in location productivity. Similarly, the level of work discontinuity (operations flow metric) can explain 52% of the variation in trade productivity. We believe this paper presents convincing evidence of the importance of construction flow in improving productivity.