2020Case2DPSGroup

Contents Lean Construction Ireland Annual Book of Cases 2020 11 Case 2 The main steps taken were: Figure 1. Schedule Duration and Logic Validation Exercise Figure 2. Standard Process Steps & Crew Sizing Figure 3. Warehouse Takt Time Plan 1 Overall Process Analysis (OPA) – This is an analysis completed at the LPS phase pull planning stage that aims to identify the different work areas (zone types) that correspond to construction phases. The analysis also looks to define the process steps and sequence of trades within the zone types. The OPA is conducted by dividing the building into areas that have the same process sequence. In this case study, six zones were identified that specifically related to the following trades’ first-fix works: Mechanical, Electrical, HVAC, and Sprinkler. Process steps for each trade were mapped for each zone and planners focused on breaking down steps to create as much repetition as possible. Like the manufacturing process, the idea is to minimise variation that would impact smooth flow. Figure 1 illustrates a preliminary mapping exercise to establish the sequence of tasks and to validate the logic of the master schedule prior to dividing the floor area into work zones. 2 Takt Analysis (TA) – The TA is based on the outcomes from the OPA results. During this step, the team considers the amount of work and the appropriate Takt time for the sequence per zone type. This is where the greatest challenges were encountered as detailed quantities of process and drainage pipelines, primary and secondary plumbing lines, ducting runs and bracketry, cable trays and number of cable pulls needed to be compiled per defined work zone. Figure 2 presents the sequencing and crew sizing for the first Takt run of 2.5 days and the second run of 5 days per zone. As a planning exercise, this was beneficial in visualising the scope and scale of the works to be completed in each zone. However, the trade supervisors deemed the work cumbersome as they were more comfortable dealing with issues and conflicts as they arose. When allocating quantities of work to be executed against available space – the pre-defined work zone – the planners were able to start generating optimum crew sizes whilst identifying which crews required time in each zone. The idea is to establish a suitable Takt time that can work for all trades in all zones. We found that some trades may have their work complete in less than the Takt time, and therefore a backlog of available work (outside the Takt zones) is needed to utilise the crews. On the other hand, larger crew sizes than the trade supervisor would have preferred may be necessary to ensure that the requisite works are completed within the Takt time. In an ideal application, the client may offer to financially supplement the extra resources or equipment needed to keep production within the Takt time. In our application, we strived to break down the task into smaller batches so that instead of having a three-person crew that needed to be four persons, we split the tasks to enable multiple smaller crews (two persons) to move more productively through the work zones. This concept is described as a “Takt Train”. 3 Applying Takt Planning to Organise the Phase Schedules – This is the step where the pre-planning work is collated to develop the Takt phase schedule. The planning team has defined how the Takt Train will be moving through the building, how many Takt zones will be handled at the same time, and what dependencies between the zones must be considered. The phase selected on this project was specifically for the first-fix installation, and it is important to note that separate Takt planning exercises should be conducted for separate phases of the project, including for example, second-fix, fit-out phase, and the commissioning and handover phase. The progression of trades through the zones is viewed as one trade in each wagon that stops in each zone for the agreed Takt time period. For example, on this pilot we simplified the durations into 2.5 days for the hangers and brackets install, and 5 days for the first-fix install. With tight daily management of zones and crew performance, it is possible to create smooth reliable flow with no idle time. The Takt plan is shown in Figure 3.