Last Planner System (LPS), also known as Collaborative Planning or Pull Planning, is a project planning method that emphasizes the involvement of the project execution/ implementation team leaders (last planners) in the planning process as the actual work get closer (Hussain, Krishna, & Kumar, 2014). It is a planning, monitoring, as well as, control system that is founded on Lean principles that was developed by Greg Howell and Glen Ballard. The aim of LPS is to create reliable and predictable production process in projects by facilitating the flow of work, building trust and collaboration within the project team, and creating a safe working environment.
LPS is founded on five basic principles. The first principle is that detailed planning should only be done when one gets closer to the work (Pellicer, Cervero, Lozano, and Tienda, 2016). This principle is found of the rationale that plans are just forecasts, and the longer the forecast, the higher the probability of it being wrong. The second principle is that plans should be produced collaboratively with those who will do the work. The third principle is that constraints on planned tasks should be identified and removed as a team. The fourth principle is that the team should make reliable promises (Hussain, Krishna, & Kumar, 2014). This principle is based on the rationale that the more detailed the forecast, the higher the probability of it being wrong.
The final principle emphasizes the need to learn from failures. According to Kalsaas (2012), LPS is a learning based system that has an inherent experiential learning cycle and facilitates single-loop learning and some simple form of double-loop learning. Similarly, the implementation of LPS requires major changes to the technical-organizational learning arena (Smith, 2011). LPS utilizes a number of tools and techniques to realize its objective including reverse phase scheduling, task hierarchy, constraints analysis, first run studies, daily huddles, reliable promising, metrics, and 5-whys analysis (Hussain, Krishna & Kumar, 2014). LSP implementation process can be broken down into five steps: preparation of master schedule, preparation of the phase schedule, preparation of look-a-head plan, preparation of weekly plan, and monitoring.
In the first phase, the collaborative team prepare a master schedule that reflects key milestones of the project (Smith, 2011). The second phase focuses on scheduling project tasks using the reverse-phase scheduling technique. This technique entails starting from the milestones and scheduling tasks backwards so as to ensure that they performed at the last possible moment; hence, reducing unnecessary accumulation of work (Kalsaas, 2012). The third phase entails developing a list of workable activities and tasks. The team is expected to analyse the preconditions for the tasks and remove all constraints. In the fourth step, the team prepares a list of tasks to be performed in each week (Hussain, Krishna & Kumar, 2014). The last phase entails assess progress in the implementation of tasks against the weekly and look-a-head plan and documenting the percentage of completed tasks. This process enables the team to identify and learn from failures
LPS is implemented in the construction setting with the view of increasing reliability, enhancing production performance, and making workflow more predictable. Ahiako, Oloke, Suresh, and Khatib (2013) examined the impact of implementing the LPS on a university construction site in Nigeria, where four prototype hostel structures were being erected simultaneously by four different contractors. Only one contractor adopted the LPD system. Data was collected using multiple methods including interviews, document analysis, observation, and questionnaires. Results revealed that the project that utilized LPC had better outcomes in terms of project completion time, average percentage plan completed (80%), and cost saving (30%).
In their study, Pellicer et al. (2016) implemented a game that sought to simulate the implementation of LPS in the real construction industry among Master of Science in Planning and Management in Civil Engineering students at the Universitat Politecnica de Valencia. The students played different roles including foreman, site manager, supplier, and subcontractors. It was observed that the implementation of LPS fostered communication, coordination, continuous improvement efforts, and commitment among the students in performing their respective roles. Priven and Sacks (2014) found that LPS improves productivity not only by enhancing technical level control, but also by strengthening relationships among parties to the project resulting in improved coordination. In this study, the authors measured the impact of implementing LPS in 12 residential construction projects over a period of 16 months. Results revealed that after LPS implementation, communication channels between project stakeholders doubled and networking improved significantly.
The study by Hamzeh, Ballard, and Tommelein (2009) utilized an action research case study design to examine whether LPS is an effective tool for guiding construction design. The authors noted that construction design processes encompass circular chain of interaction and iterative activities that make it difficult to implement standardized planning tools. In this study, LPS principles and steps were applied at the Cathedral Hill Hospital (CHH) project in San Francisco. Findings show that after implementation of LPS, designers and architects became more comfortable in planning weekly activities, there was improved communication within and among clusters, rapid deployment of planning process, and greater involvement of the project owner and other core stakeholders. These findings suggest that LPS is also an effective method for guiding construction design activities. However, the study had a significant limitation in that there was no information regarding the practices of parties involved in the development of CHH design prior to the implementation of LPS; hence, it not clear whether the observation made actually represent an improvement in design practices.