Lean Construction Ireland Annual Book of Cases 2021 54 their root causes. In addition, the process of resolving issues required fact-based decision making, and for this we needed to understand what the contributory factors to the issue were and to measure their impact. Figure 1 shows an unbalanced panel being lifted into position. A successful installation depends on the panel being presented evenly to the starter bars in the floor slab.To achieve this, the left-heavy side of the panel must be dropped vertically into place and level with the right side of the panel.The trial-and-error method meant that the panel had to be lifted back to the stillage and re-configured. We mapped the process to understand the steps involved, from the arrival of the panel on site to its final placing in position (see Figure 2). Figure 2. As-Is Process Map for Precast Panel Installation We then used the process as the spine of a SIPOC diagram (see Figure 3). Figure 3. SIPOC for Precast Panel Installation Measure Figure 4 presents an isometric view of a typical floor, and shows that on Level 03 Block D2 there are 24 unbalanced panels. Over the 3 blocks, each with 8 floors, we identified 969 potentially unbalanced panels.The details for each floor and block are shown inTable 1. We measured the time taken to install 24 unbalanced panels from chain engagement to panel dropping on the slab on one of the blocks using the current process.The sum of these times was 7 hours, 34 minutes, and 36 seconds, equating to an average time per panel of 18 minutes and 56 seconds. By comparison, for a standard balanced panel, installation was completed in less than 6 minutes. Analyse In the analysis phase,we used a Fishbone Diagram (see Figure 5) to understand contributory factors to the problem. From this review we identified two main factors impacting the installation time: i. The as-built anchor locations on the panels did not conform to the design locations. ii. Due to a lack of communication between the precast panel factory and on-site precast installation crew, chain lengths had to be determined based on the actual locations of the lifting eyes. While a major process error was found in the positioning of the lifting anchors,we decided to focus our improvement efforts on the time taken to manage chain lengths. Figure 5. Fishbone Diagram for the Process of Lifting PrecastWalls Figure 4. IsometricView of aTypical Floor Plan Case 14 Table 1. Potential Number of Unbalanced Panels in Blocks A1, A2, B1
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