Lean Construction Productivity & Quality

Jati Utomo Dwi Hatmoko

Lean Construction (LC)

• Lean = slim, not fat • Goal :

– better meeting customer needs while using less of everything.

– to avoid “muda” (Japanese terminology for the waste of energy, money, talent and time).

• LC maximizes value and reduces waste • LC 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)

• Lean construction results from the application of a new form of production management to construction.

• Essential features of lean construction include: – a clear set of objectives for the delivery process,

– aimed at maximizing performance for the customer at the project level,

– concurrent design of product and process, and

– the application of production control throughout the life of the product from design to delivery.

• LC uses Supply Chain Management (SCM) and Just-In-Time (JIT) techniques as well as the open sharing of information between all the parties involved in the production process.

• LC emphasizes seamless integration of production facilities/processes, vendors, suppliers, and subcontractors.

Construction Context

Sowards stated (2004) the priority for all construction work is to:

• keep work flowing so that the crews are always productive installing product;

• reduce inventory of material and tools and

• reduce costs.

HISTORY OF LEAN PRODUCTION • Developed by Toyota led by Engineer Taichi Ohno 1950’s

• Ohno had observed mass production at Ford Motor Corporation’s manufacturing facilities in the U.S. and recognized that there was much waste everywhere.

• Ohno identified seven wastes in mass production systems :

– overproducing,

– waiting time,

– transporting,

– processing itself,

– having unnecessary stock on hand,

– Using unnecessary motion

– producing defective goods.

• Ohno visualized a failure to meet customers’ needs as waste

• The term “lean” was coined by the research team working on international auto production to reflect both the waste reduction nature of the Toyota production system and to contrast it with craft and mass forms of production

HISTORY OF LEAN PRODUCTION

• He developed a simple set of objectives for the design of the production system: Produce a car to the requirements of a specific customer, deliver it instantly, and maintain no inventories or intermediate stores.

• Rework due to errors could not be tolerated as it reduced throughput, the time to make a car from beginning to end, and caused unreliable workflow.

• Ohno also decentralized shop floor management by making visible production system information to everyone involved with production. “Transparency” allowed people to make decisions in support of production system objectives and reduced the need for more senior and central management.

LEAN CONSTRUCTION

• Lean construction accepts the Ohno’s production system design criteria as a standard of perfection.

But how does the Toyota system, lean production, apply in construction?

• The construction industry has rejected many ideas from manufacturing because of the belief that construction is different.

• Manufacturers make parts that go into projects but the design and construction of unique and complex projects in highly uncertain environments under great time and schedule pressure is fundamentally different from making tin cans.

What is waste??

Examples of waste??

WASTE Anything that Consumes Resources but Does Not Provide Value for the Customer

1. Overproduction 2. Waiting 3. Inventory

4. Movement 5. Effort 6. Rework of Errors 7. Processing

Waste : anything that consumes resources but creates no value for the customer.

WASTES IN CONSTRUCTION

1. Over production:

* Putting as much work in place as possible, making it harder to do priority work.

* Ordering additional material because or poor quality.

2. Waiting: for materials, direction, imformation or prerequesite work.

3. Inventory : Information or material delivered before it is needed.

4. Movement : Moving materials frome one place to another place before it installing.

5. Effort :

* Returning to the shop to pick up plans, materials or tools not at the site

* Hunting to information or tools.

6. Rework : Re-doing work because of errors.

7. Processing :

* Recreating work because it cannot to be shared

* Expediting materials not ordered on time.

* Excessive coordination of multiple levels of suppliers.

The seven types of waste found in construction

• Defects.

Everyone in construction understands this type of waste. It includes doing the wrong installation, defects in fabrication, and errors in punch lists. Not meeting the required code is waste. Rework in construction is rarely measured.

• Overproduction of goods .

This happens when we fabricate material too early or stockpile material in the warehouse or at the job site. Estimating and bidding jobs that are not won is a form of this waste. Printing more blueprints or making more copies of a report than needed is overproduction.

• Transportation.

This waste occurs when we move material around the shop, when we load it on the truck or trailer, when we haul it to the job site, when we unload it, and when we move the material from the lay-down or staging area to the installation point.

The seven types of waste found in construction

• Waiting.

Construction is full of this waste, including when a crew waits for instructions or materials at the job site, when a fabrication machine waits for material to be loaded, and even when payroll waits for the always-late timesheets.

• Overprocessing.

This waste includes overengineering, requiring additional signatures on a requisition, multiple handling of timesheets, duplicate entries on forms, and getting double and triple estimates from suppliers.

• Motion/movement.

These “treasure hunts” happen when material is stored away from the job or when workers look for tools, material, or information. This waste also occurs in the office or job site trailer, when looking for files, reports, reference books, drawings, contracts, or vendor catalogues.

The seven types of waste found in construction

• Overproduction / Inventory .

This includes uncut materials, work in process, and finished fabrications.

Some contractors claim that they have no inventory because they job-cost all material. While this may work for accounting, if the material is not yet installed and isn’t being used by the customer, it’s waste. This waste includes spare parts, unused tools, consumables, forms and copies, employee stashes, and personal stockpiles. One could argue that the unfinished facility is inventory and is waste until operational.

Lean Construction Tools

• Last Planner System • other lean tools already proven in manufacturing have

been adapted to the construction industry with equal success. – 5S – Kanban, – Kaizen events, – quick setup/changeover, – Poka Yoke, – Visual Control – Five Whys

• JIT • SCM

5 S / 5 R • 5S is the name of a workplace organization methodology that uses a list of five

Japanese words which, transliterated and translated into English, start with the letter S.

• The list describes how items are stored and how the new order is maintained. The decision making process usually comes from a dialogue about standardization which builds a clear understanding among employees of how work should be done. It also instills ownership of the process in each employee.

– Phase 1 - Seiri (整理) Sorting:

– Phase 2 - Seiton (整頓) Straighten or Set in Order:

– Phase 3 - Seisō (清掃) Sweeping or Shining or Cleanliness (Systematic Cleaning):

– Phase 4 - Seiketsu (清潔) Standardizing:

– Phase 5 - Shitsuke (躾) Sustaining the discipline:

5R - Ringkas, Rapi , Resik , Rawat , Rajin

5 S • Phase 1 - Seiri (整理) Sorting:

Go through all tools, materials, etc., in the plant and work area.

Keep only essential items.

Everything else is stored or discarded.

• Phase 2 - Seiton (整頓) Straighten or Set in Order: There should be a place for everything and everything should be in its place.

The place for each item should be clearly labeled or demarcated.

Items should be arranged in a manner that promotes efficient work flow.

Workers should not have to repetitively bend to access materials.

Each tool, part, supply, piece of equipment, etc. should be kept close to where it will be used (i.e. straighten the flow path).

Seiton is one of the features that distinguishes 5S from "standardized cleanup".

5S

• Phase 3 - Seisō (清掃) Sweeping or Shining or Cleanliness (Systematic Cleaning):

Keep the workplace clean as well as neat.

At the end of each shift, clean the work area and be sure everything is restored to its place.

This makes it easy to know what goes where and insures that everything is where it belongs.

A key point is that maintaining cleanliness should be part of the daily work - not an occasional activity initiated when things get too messy.

5 S • Phase 4 - Seiketsu (清潔) Standardizing:

Work practices should be consistent and standardized.

Everyone should know exactly what his or her responsibilities are for adhering to the first 3 S's.

• Phase 5 - Shitsuke (躾) Sustaining the discipline: Maintain and review standards.

Once the previous 4 S's have been established, they become the new way to operate.

Maintain focus on this new way and do not allow a gradual decline back to the old ways.

While thinking about the new way, also be thinking about yet better ways.

When an issue arises such as a suggested improvement, a new way of working, a new tool or a new output requirement, review the first 4 S's and make changes as appropriate.

5 S • A sixth phase, "Safety," (安全) is sometimes added.

It is reasonable to assume that a properly planned and executed 5S program will inherently improve workplace safety, but some argue that explicitly including this sixth S insures that workplace safety is given primary consideration.

It is important to have continuous education about maintaining standards.

When there are changes that affect the 5S program such as new equipment, new products or new work rules, it is essential to make changes in the standards and provide training.

Companies embracing 5S often use posters and signs as a way of educating employees and maintaining standards.

Kaizen

• Kaizen (Japanese for "improvement" or "change for the better")

It refers to a philosophy or practices that focus upon continuous improvement of processes in manufacturing, engineering, supporting business processes, and management

Just-in-Time (JIT)

• Just-in-Time (JIT) : A philosophy of manufacturing based on planned elimination of all waste and on continuous improvement of productivity.

• It encompasses the successful execution of all manufacturing activities required to produce a final product, from design engineering to delivery, and includes all stages of conversion from raw material onward.

• Principles:

– minimizing waste in all forms,

– continuous improvement of processes and systems,

– maintaining respect for all workers

JIT is a pull system that responds to actual customer demand.

products are “pulled from ” the JIT system.

JIT : A system of production that makes and delivers just what is needed, just when it is needed, and just in the amount needed.

JIT only commits the resources needed to meet the customer’s needs.

In the mid – 1970’s Toyota reduced the time needed to produce a car from fifteen days to one day, using JIT.

Just-in-Time (JIT) • The primary elements of Just-in-Time :

– to have only the required inventory when needed;

– to improve quality to zero defects;

– to reduce lead times by reducing setup times, queue lengths, and lot sizes;

– to incrementally revise the operations themselves; and

– to accomplish these activities at minimum cost.

– In the broad sense, it applies to all forms of manufacturing-job shop, process, and repetitive-and to many service industries as well.

• Results:

– reduced inventories (and space),

– Higher human productivity;

– better equipment productivity and utilization,

– shorter lead times,

– Fewer errors, and

– higher morale.

Synonims: short-cycle manufacturing, stockless production, zero inventories.

Poka-yoke

• Poka-yoke (ポカヨケ?) [poka yo-ke] is a Japanese term that means "fail-safing" or "mistake-proofing".

• A poka-yoke is any mechanism in a lean manufacturing process that helps an equipment operator avoid (yokeru) mistakes (poka).

• Its purpose is to eliminate product defects by preventing, correcting, or drawing attention to human errors as they occur.

• The concept was formalised, and the term adopted, by Shigeo Shingo as part of the Toyota Production System.

• originally described as baka-yoke, but as this means "fool-proofing" (or "idiot-proofing") the name was changed to the milder poka-yoke.

Poka-yoke: Implementation in manufacturing

• Poka-yoke can be implemented at any step of a manufacturing process where something can go wrong or an error can be made.

• For example – a jig that holds pieces for processing might be modified to only allow

pieces to be held in the correct orientation,

– a digital counter might track the number of spot welds on each piece to ensure that the worker executes the correct number of welds.

• Shigeo Shingo recognized three types of poka-yoke for detecting and preventing errors in a mass production system: – The contact method identifies product defects by testing the product's

shape, size, color, or other physical attributes. – The fixed-value (or constant number) method alerts the operator if a

certain number of movements are not made. – The motion-step (or sequence) method determines whether the

prescribed steps of the process have been followed.

Designing LC system

Womack and Jones (1996) identified five key principles that need to be observed when lean construction systems are designed.

1. Value: There is a need to clarify the customer’s needs, and the agents involved in all stages from inception to the delivery process, in order to clarify activities or products that signify value.

2. Value stream: By mapping the whole value stream, establishing cooperation between the participants, and identifying and eliminating waste, the construction process can be improved.

3. Flow: – Business flow includes project information (specifications, contracts, plans, etc.). – Job site flow involves the activities and the way they have to be done. – Supply flow refers to the materials used in a project.

4. Pull: The efforts of all participants stabilize pulls during the construction process. 5. Perfection: Work instructions and procedures are developed, and quality

controls are established.

The implementation of LC consists of the following steps:

• Defining what is valuable to the client

• Planning a sequence of activities required to deliver the defined values

• Achieving an efficient flow of work

• Performing work only where it is needed to advance these values

• Seek perfection through continuous application of the preceding steps.

the main principles of lean production

According to Koskela (1998), the main principles of lean production include the following:

• increase the efficiency of value adding activities, associated to the improvement of production technology and production skills;

• reduce the share of non value adding activities, leading to simplification, reduction of variability and increasing flexibility;

• ensure product specifications, thus improving customer value;

• and improve in a comprehensive and integrated way, balancing actions oriented to implement lean production principles in design, control and production systems.

Supply Chain Management (SCM)

• Focuses on logistics

– to control the interface between suppliers and Toyota, facilitating the provision of supplies precisely on time, in required quantities.

• A supply chain encompasses all the activities that lead to having an end user provided with a product or service – the chain is comparable to a network that provides a conduit for flows in both directions, such as materials, information, funds, paper, and people.

• It typically effects major economies by reducing inventories.

• SCM has been developed further as a management concept and incorporates features of JIT.