Differences between Lean Construction approach and PMI approach

Differences between Lean Construction approach and PMI approach
Las diferencias entre el enfoque y la magra PMI enfoque se enumeran a continuación:

La gestión de la interacción entre las actividades y los efectos combinados de la dependencia y la variación, es una primera preocupación magra en la construcción debido a que sus interacciones altamente afecta el tiempo y el coste de los proyectos (Howell, 1999), en comparación, estas interacciones no son considerados en el PMI।

En la construcción de optimización magra esfuerzos se centran en hacer flujo de trabajo fiable (Ballard, LPDS, 2000), en contraste PMI se centra en la mejora de la productividad de cada una de las actividades que podemos hacer fallos y la reducción de la calidad y resultado en la revisión

El proyecto está estructurado y gestionado como un proceso de generación de valor (valor se define como la satisfacción de las necesidades de los clientes) (Howell, 1999), mientras que PMI considera como un costo menor valor

En magra enfoque, los usuarios interesados participan en delantero finales de planificación y diseño funcional a través de equipos de la Cruz (Ballard, LPDS, 2000); por otra parte, PMI no considera que esta importante cuestión। En magra construcción, control de los proyectos tiene la tarea de ejecución (Ballard, tesis doctoral, 2000) y que, en el control de PMI método se basa en la detección de diferencia después del hecho. En magra método, las técnicas de tracción se utilizan para regular el flujo de materiales e información a través de redes de cooperantes especialistas (Ballard, tesis doctoral, 2000), en cambio, PMI utiliza técnicas para empujar la liberación de la información y los materiales. Inventario y la capacidad de buffers se utilizan para absorber variabilidad. Comentarios bucles se incluyen a todos los niveles, para hacer un rápido sistema de ajustes, (Ballard, tesis doctoral, 2000), en comparación, PMI no considera ajustes. Lean la construcción trata de mitigar la variabilidad en todos los aspectos (calidad del producto, tipo de trabajo) y gestionar el resto de la variabilidad, mientras que PMI no considera la variabilidad de mitigación y gestión. (Ballard, tesis doctoral, 2000) Lean enfoque intenta hacer mejoras continuas en el proceso, los flujos de trabajo y de los productos (Howell, 1999); enfoque PMI que no paga mucho más que la atención a la mejora continua. En magra la construcción, la toma de decisiones se distribuye en el diseño de sistemas de control de producción (Ballard, tesis doctoral, 2000), por comparación, PMI en la toma de decisiones se centra en un gestor de algunas veces. Lean la construcción intenta aumentar la transparencia entre las partes interesadas, gestores y trabajadores, a fin de conocer el impacto de su trabajo en todo el proyecto (Howell, 1999); por otra parte, PMI no se considera la transparencia en sus métodos. En una magra método de amortiguación del sonido se mantiene asignaciones para cada uno de la tripulación o unidad de producción (Ballard, tesis doctoral, 2000), en cambio, PMI método no se considera un atraso de las tripulaciones. Lean la construcción está tratando de desarrollar nuevas formas de contrato comercial para dar incentivos a los proveedores confiables para flujo de trabajo y la optimización en la entrega a la cliente-nivel (Howell, 1999), mientras que PMI no tiene esa política. Lean la construcción del diseño de control de la producción se resiste a la tendencia hacia suboptimization local. (Ballard tesis), sin embargo, persiste la PMI en la optimización de cada actividad. El PMI-enfoque sólo considera la gestión de un proyecto en el macro-nivel. Esto es necssary pero no suficiente para el éxito de los proyectos. Lean proyecto abarca la construcción y gestión de la producción, y oficialmente se reconoce que el éxito de cualquier proyecto de empresa, inevitablemente, implican la interacción entre proyecto y gestión de la producción ".

Last Planner System

Last Planner System
The Last Planner System (LPS) improves both design and construction schedule/programme predictability – work completed as and when promised. It is a system of inter-related elements – full benefits come when all are implemented together, over time. Based on simple paper forms, it can be administered using Post-it notes, paper, pencil, eraser and photocopier. A spreadsheet can help.
LPS begins with collaborative scheduling/programming engaging the main project suppliers from the start. Risk analysis ensures that float is built in where it will best protect programme integrity and predictability. Where appropriate the process can be used for programme compression too. In this way, one constructor took 6 weeks out of an 18-week programme for the construction of a 40 bed hotel. Benefits to the client are enormous.
Figure 1: intense discussion during a programme compression workshop
Before work starts, team leaders make tasks ready so that when work should be done, it can be. Why put work into production if a pre-requisite is missing? This MakeReady process continues throughout the project.
Figure 2: part of a MakeReady form for documenting the process of making tasks ready (this one for use in design)
There is a weekly work planning (WWP) meeting involving all the last planners – design team leaders and/or trade supervisors on site. It is in everyone’s interest to explore inter-dependencies between tasks and prevent colleagues from over-committing.
Figure 3: part of a Weekly Work Plan form used by trade foremen on site or design team leaders to prepare for the WWP meeting.
This weekly work planning processes is built around promises. The agreed programme defines when tasks should be done and acts as a request to the supplier to do that task. The last planners (that is the trade foremen on site or design team leaders in a design process) only promise once they have clarified the conditions of satisfaction and are clear that the task can be done.
Figure 4: the promise cycle (after Fernando Flores)
Once the task is complete the last planner responsible declares completion so that site management or the next trade can assure themselves that it is complete to an appropriate standard.
A key measure of the success of the Last Planner system is PPC. This measures the Percentage of Promises Completed on time. As PPC increases. project productivity and profitability increase, with step changes at around 70% and 85%. This score is measured site-wide and displayed around the site. Weekly measures are used by the project and by individual suppliers as the basis for learning how to improve the predictability of the work programme and hence the PPC scores.
A key part of the continual improvement process is a study of the reasons why tasks promised in the WWP are delivered late. The following chart shows typical reasons:
Figure 5: example of a reasons Pareto chart
Recording the reasons in a Pareto chart like the one above makes it easy to see where attention is most likely to yield the most results. Using tools like 5 Why analysis and cause-effect diagrams will help the team understand how they can improve the clarity of information and ensure that there are sufficient operatives.
Last Planner benefits don’t stop at project predictability, profit and productivity; it contributes to positive changes in other industry KPIs. Danish research shows almost half the accidents and up to 70% less sickness absence on LPS managed sites.
Last Planner System development continues under the direction of Lean Construction Institute Directors Professor Glenn Ballard and Greg Howell with support from users around the world. For more information about the development process see Ballard (1994, 2000) and Ballard & Howell (2004) for example
For a more detailed description and list of benefits see here For more on Learning how to implement Last Planner see here

What is lean construction?

What is lean construction?
Lean construction is a “way to design production systems to minimize waste of materials, time, and effort in order to generate the maximum possible amount of value (Koskela et al. 2002) ”. Designing a production system to achieve the stated ends is only possible through the collaboration of all project participants (Owner, A/E, Constructors, Facility Managers, End-user) at early stages of the project. This goes beyond the contractual arrangement of design/build or constructability reviews where constructors, and sometime facility managers, merely react to designs instead of informing and influencing the design.
Lean construction aims to embody the benefits of the Master Builder concept. Essentially, Lean Construction recognizes that desired ends affect the means to achieve these ends, and that available means will affect realized ends (Lichtig 2004).
Lean construction supplements traditional construction management approaches with: (1) two critical and necessary dimensions for successful capital project delivery by requiring the deliberate consideration of material and information flow and value generation in a production system; and (2) different project and production management (planning-execution-control) paradigms.
While lean construction is identical to Lean Production in spirit, it is different in how it was conceived as well how it is practiced.
The common spirit flows from shared principles:
Whole System Optimisation through Collaboration and systematic learning
continual improvement/pursuit of perfection involving everyone in the system
a focus on delivering the value desired by the owner/client/end-user
allowing value to flow by systematically eliminating obstacles to value creation and those parts of the process that create no value
creating pull production
The differences in detail flow from a recognition that construction is a project based production where the product is generally a prototype.
As Sowards stated (2004) the priority for all construction work is to:1) keep work flowing so that the crews are always productive installing product;2) reduce inventory of material and tools and3) reduce costs.
While Lean Construction’s main tool for improvement in construction is the Last Planner System (see below), other lean tools already proven in manufacturing have been adapted to the construction industry with equal success. These include: 5S, Kanban, Kaizen events, quick setup/changeover, Poka Yoke, Visual Control and Five Whys (Mastroianni and Abdelhamid 2003, Salem et al 2005). Other Lean tools may prove useful once tested in construction.
Cain (2004 [- a or b Clive?]) suggests lean construction be defined by six goals of construction best practice:
1. Finished building will deliver maximum functionality, which includes delighted end users.
2. End Users will benefit from the lowest optimum cost of ownership.
3. Inefficiency and waste in the use of labor and materials will be eliminated.
4. Specialist suppliers will be involved in design from the outset to achieve integration and buildability.
5. Design and construction will be through a single point of contact for the most effective co-ordination and clarity of responsibility.
6. Current performance and improvement achievements will be established by measurement.
"One can think of Lean Construction in a way similar to mesoeconomics. Lean Construction draws upon the principles of project-level management and upon the principles that govern production-level management. Lean Construction recognizes that any successful project undertaking will inevitably involve the interaction between project and production management." (Abdelhamid 2007)

Practical applications
(it would be good to add examples from other countries here such as Denmark, US, Chile, Brasil, Peru, Sweden, in addition to others from the UK)
In the UK, a major R&D project, Building Down Barriers, was launched in 1997 to adapt the Toyota Production System for use in the construction sector. The resulting supply chain management toolset was tested and refined on two pilot projects and the comprehensive and detailed process-based toolset was published in 2000 as the 'Building Down Barriers Handbook of Supply Chain Management-The Essentials'. The project demonstrated very clearly that lean thinking would only deliver major performance improvements if the construction sector learned from the extensive experience of other business sectors. Lean thinking must become the way that all the firms in the design and construction supply chain co-operate with each other at a strategic level that over-arches individual projects. In the aerospace sector, these long-term supply-side relationships are called a 'Virtual Company', in other business sectors they are called an 'Extended Lean Enterprise'.
The UK 'Building Down Barriers Handbook of Supply Chain Management-The Essentials' states that: 'The commercial core of supply chain management is setting up long-term relationships based on improving the value of what the supply chain delivers, improving quality and reducing underlying costs through taking out waste and inefficiency. This is the opposite of 'business as usual' in the construction sector, where people do things on project after project in the same old inefficient ways, forcing each other to give up profits and overhead recovery in order to deliver at what seems the market price. What results is a fight over who keeps any of the meagre margins that result from each project, or attempts to recoup 'negative margins' through 'claims', The last thing that receives time or energy in this desperate, project-by-project gladiatorial battle for survival is consideration of how to reduce underlying costs or improve quality'.

Sobre Lean Construction

Lean construction

Lean construction is a translation and adaption of lean manufacturing principles and practices to the end-to-end design and construction process. Unlike manufacturing, construction is a project based-production process. Lean construction is concerned with the holistic pursuit of concurrent and continuous improvements in all dimensions of the built and natural environment: design, construction, activation, maintenance, salvaging, and recycling. This approach tries to manage and improve construction processes with minimum cost and maximum value by considering customer needs. (Koskela et al. 2002)
The term "Lean Construction" was coined by the International Group for Lean Construction in its first meeting in 1993.

Historical Development
The seminal work of Lauri Koskela in 1992 challenged the Construction Management community to consider the inadequacies of the time-cost-quality tradeoff paradigm. Another paradigm-breaking anomaly was that observed by Ballard (1994), Ballard and Howell (1994a and 1994b), Howell and Ballard (1994a and 1994b) and Howell (1998). Analysis of project plan failures indicated that “normally only about 50% of the tasks on weekly work plans are completed by the end of the plan week” and that constructors could mitigate most of the problems through “active management of variability, starting with the structuring of the project (temporary production system) and continuing through its operation and improvement.” (Ballard and Howell 2003).
Evidence from research and observations indicated that the conceptual models of Construction Management and the tools it utilizes (work breakdown structure, critical path method, and earned value management) fail to deliver projects ‘on-time, at budget, and at desired quality’ (Abdelhamid 2004). With recurring negative experiences on projects, evidenced by endemic quality problems and rising litigation, it became evident that the governing principles of construction management needed revisiting. In fact, a respondent to the 6th annual Survey of Construction Owners by CMAA (2006) included a comment: "While the cost of steel and cement are making headlines, the less publicized failures in the management of construction projects can be disastrous. Listen carefully to the message in this comment. We are not talking about just materials, methods, equipment, or contract documents. We are talking about how we work to deliver successful capital projects and how we manage the costs of inefficiency."

A New Paradigm
Koskela (2000) argued that the mismatch between the conceptual models and observed reality underscored the lack of robustness in the existing constructs and signaled the need for a theory of production in construction. Koskela then used the ideal production system embodied in the Toyota Production System to develop a more overarching production management paradigm for project-based production systems where production is conceptualized in three complementary ways, namely, as a Transformation (T), as a Flow(F), and as Value generation(V). Koskela and Howell (2002) have also presented a comprehensive review of the shortcomings existing management theory – specifically as related to the planning, execution, and control paradigms – in project-based production systems. Both conceptualizations provide a solid intellectual foundation of Lean Construction as evident from both research and practice.
Recognizing that construction sites reflect prototypical behavior of complex and chaotic systems, especially in the flow of both material and information on and off site, Bertelsen (2003a and 2003b) suggested that construction should be modeled using chaos and complex systems theory. Bertelsen (2003b) specifically argues that construction could and should be understood in three complimentary ways, namely, as a project-based production process, as an industry that provides autonomous agents, and as a social system. With more developments in this line of thinking, it is very likely that the Lean Construction governing paradigm will change to it. And so, the process will keep on repeating!