Last edited 20 Apr 2021

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ConSIG CWG Institute / association Website

Lean Construction - A Quality Perspective


[edit] Introduction

The integration of lean into the construction industry has been growing rapidly over the last few years as more and more contractors have begun to understand the benefits of applying lean thinking to a construction environment. The principles of lean construction are simple enough; maximise the delivery of value for the customer whilst at the same time minimising the amount of waste to produce this value. Lean construction is based on the ‘Just in Timemanufacturing principles of the Toyota Production System created by Japanese Industrial Engineers Eiji Toyoda and Taiichi Ohno in the late 1940’s.

One of the difficulties of applying the idea of lean thinking to a construction environment is that unlike manufacturing, the work we do in construction isn’t always in a controlled environment. This often leads to greater variation in what we do which can make our work at times unpredictable, unreliable, inefficient and sometimes difficult to achieve. Another hurdle to overcome is that there is no single solution, method or process to achieve it.

There are numerous tools, techniques and methodologies that have been developed in an attempt to translate lean thinking to construction each of which can be used on their own but more often can be combined. The issue comes from a lack of understanding of which tools work well together or having a standard approach to implementing them. This often sees the introduction of lean and the creation of a lean culture fail early in its implementation on our projects.

Driving productivity, efficiently and effectively whilst improving quality, reducing costs and construction times of our projects can all be achieved through the successful implementation of lean principles. These principles will guide you to discovering and developing the tools and methodologies required to achieve a lean culture that challenges what it does every day, is intolerant of waste and takes an open minded approach to project delivery.

[edit] An introduction to the 5 core principles of lean

Core Principles of Lean.jpg

[edit] Principle 1: Identify value (from the client’s perspective)

Value: The regard that something is held to deserve; the importance, worth, or usefulness of something:

The key difference that lean adds to this is that value (ie; regard, importance, worth and usefulness) must only be seen from the eyes of the customer. Every company needs to understand what value the customer places upon their products and services. It is this value that determines how much money the customer is willing to pay for those products or services.

Therefore, value is defined as how well a product or service meets a customer’s requirements. If it’s something a customer is willing to pay for, it has value.

Speaking plainly, the different activities performed during a process either add value to the end product or they don’t.

So activities can be either:

To determine if a procedure or activity adds value, you need to be able to answer “yes” to three questions:

  • Does it fulfil a customer’s need or preference?
  • Does it change the product or service in some way?
  • Is it done right the first time in the process?

Be warned: Sometimes in construction we can spend a lot of time and money doing work that seems important to us. Understanding this may result in certain tasks, people or whole departments having an unpleasant shock when they realise that what they do and feel is important, does not add any value to the customer!!

Through the use of such tools as ‘Voice of the Customer’ (VOC) and ‘Critical to Quality’ (CTQ Trees) we can identify, understand, plan and manage our clients’ expectations. Generally speaking what the client actually wants from our projects usually goes beyond what is set out in its contracts and goes beyond the quality of our work or completing the project on time to the agreed cost. Through early engagement we can grow the relationship with the client which in turn generates strong levels of trust. Only once you have this level of relationship can you begin to challenge what is expected in order to successfully implement lean practices and truly deliver the value the client desires.

[edit] Principle 2: Understand your value stream

The value stream is simply what the client values. Once you’ve identified value from your client’s perspective using the tools mentioned above, it’s time to identify the processes needed to deliver that value.

It is vital that we understand the full end-to-end process from conception to completion starting with the very end of the process, the customer. This is simply so that you can understand what you are working with and how you can make improvements to ensure the delivery of the value mentioned in step 1 that the client desires.

This full end-to-end process is called the Value Stream and is defined as…

‘All of the elements and actions from conception to completion that are required to deliver the product or service that the customer requires.’

By understanding the value stream you can identify the value adding steps and then the non-value adding and waste steps. This gives you the opportunity to minimise or eliminate non-value adding and wasteful steps and optimise the steps that add value. Only by having a clear understanding of the value stream can a company truly understand the waste associated with the manufacture and delivery of its products or services. Lean thinking creates the platform for the understanding of supplier and customer partnerships along with supply chain management to help eliminate waste across the entire value stream.

[edit] Principle 3: Create flow

The previous two steps were intended to define the goal we should be aiming for and then the current state of our existing processes.

In a perfect world – delivering a service or making a product for your customer would happen instantaneously. It would just ‘appear’ without any work – as if by magic. However in the real world, time, distance, availability, skill, and resources can and often do add constraints to a process. This actually means that we generally have to work very hard to manage these constraints so that we can give the customer what they want.

So the aim in any lean operation is to make the process steps to deliver your value stream as joined-up, effectively and efficiently and as quickly as possible.

In other words we strive to allow a process to flow like a river moving from one value adding step to another and so on. These various steps required to provide the product or service should link together seamlessly, in tight sequence, without delay – so the process will flow smoothly. If the value stream stops moving forward for any reason, then waste will occur. The ultimate goal is to create a value-stream where the product (or its raw materials, components or sub-assemblies) never stop during the production process and that each stage of production is done in sequence. In order to achieve flow all parties have to communicate and work together to avoid interruptions. You want to avoid workers waiting for work or vice versa.

Dividing a project up into separate production areas can help contractors ensure they have the capacity to finish each task on schedule. If one stage of production gets behind or ahead of schedule, it’s important to communicate and make adjustments to avoid the workers waiting for work.

As you begin the exercise of creating the value stream each step in the process should be carefully mapped to determine what activities are involved. Take into account labour, information, materials, and equipment needed for each activity. Any steps in a process that don’t add value for you client should be eliminated or at the very least minimised and rigorous control methods put in place to stop them becoming excessive.

The goal in lean construction is to achieve a continuous workflow that is reliable and predictable.

[edit] Identifying and eliminating waste

In lean construction we often talk about the ‘eight wastes’ and use the acronym DOWNTIME to remember them. Some companies use TIMWOODS, however sending out an email to your organisation or project team introducing Tim Woods as the newest member of the business Improvement team can cause managers to question who gave you the authority to recruit. YES this has happened!

Lean Wastes.png

Let’s look at the different types of waste we can see in our processes.

[edit] Defects

This is anything not completed correctly the first time which then results in rework. This waste comes from the time it takes in having to make the repairs and the extra materials needed to correct the work.

[edit] Overproduction

In construction, this type of waste occurs when a task is completed faster than scheduled which results in the next task in the sequence not being ready to start. There are some great tools that can be used to combat this including collaborative planning, the last planner system and having a fully functioning project management office that manages the hourly, daily and weekly activity outputs.

[edit] Waiting time

This is wasted time associated when workers within the value stream have had to stop what they are doing. This is often caused by delays in material being delivered to site or preceding work that hasn’t been completed. Even simple things like authorised paperwork not being received to commence the work causes waiting time. This disrupts the workflow in the value stream and results in workers waiting for work.

[edit] Not utilising talent

This is the worst waste and the most important waste to eradicate. Having the wrong people performing the work whether they are over or under qualified to do it will result in the work being done incorrectly or not at all. You wouldn’t hire an electrician to operate a digger nor would you expect a construction labourer to manage the project leadership team, it would be a complete waste of their talents, skills, and knowledge. Not utilising our talent is the only one of the eight wastes that can have either a positive effect; can reduce the other 7 wastes or a negative effect; can make the other 7 wastes worse. Having the right people with the right skillset engaged in a manner that makes the best use of their abilities and knowledge will help to drive down the impact of each of the other 7 waste types. Fix this first before attempting to fix the others!

[edit] Transport

This is the transportation of equipment, materials, and workers to a project worksite before they are needed.

[edit] Inventory

In lean construction, we should be moving towards a “just in timeinventory system rather than a “just in case” inventory. Inventory costs money, lots of money in the construction sector, a lot of it has shelf life and in some cases doesn’t like to spend a lot of time exposed to the elements. If you don’t need it, don’t have it! Work with your supply chain through early engagement to create a plan of works that takes into account manufacturing lead and delivery times that meet the needs and demands of the value stream.

[edit] Motion

This is any unnecessary movement associated with people that can be eliminated, this can include having to make multiple trips across the project worksite to get more tools or materials.

[edit] Excess processing

Excess processing is typically generated when having to deal with too many instances of other waste such as defects or inventory. Double-checking or adding extra processes to try and eliminate other areas of waste will involuntarily lead to more waste from over processing. Typically in construction we tend to see designs that are far beyond the scope the customer requires, yes it’s nice to give the customer a little bit extra, but only if they are willing to pay for it.

Once the waste has gone we can begin to achieve 'flow' in our processes.

[edit] Principle 4: Create pull through the value stream

To do this we must control what and when things are done, ensure that nothing is made ahead of time and builds up work-in-process inventory that stops the synchronised flow of the value stream. This is called a pull approach.

A traditional western manufacturer will use a style of production planning and control whereby production is "pushed" through the value stream based upon a forecast and a schedule.

A pull approach states that we do not make anything until the customer orders it. To achieve this requires great flexibility and very short cycle times of design, production, and delivery of the products and services. It also requires a mechanism for informing each step in the value chain what is required of them today, based upon meeting the customer’s needs. When we get to a project work site we often use a technique known as 'short interval control' alongside our collaborative planning model to create this flexibility in our delivery.

[edit] The collaborative planning approach

When planning or scheduling the work we base it on the demand of the next step in our value stream in order to create a reliable workflow. This method helps to embed the flow principle and control the pull of a process this is because the work we do is usually done in a sequential manner and the completion of one task releases work for the next task. To do this requires starting from a specific milestone or target completion date and working backward to schedule work when it can be performed.

In lean construction pull planning is often done by those performing the work, typically the subcontractors, through communication, collaborative planning and daily works planning sessions with each other to dictate the schedule of tasks. This is because they are best suited for determining their capacity for performing a given task. These sessions often see subcontractors working with the next subcontractor, or customer, downstream to coordinate schedules and handovers.

[edit] Principle 5: Strive for perfection

The key here is to understand that perfection doesn’t exist it is a mythical target we are continually aiming for.

The idea of total quality management is too systematically and continuously remove the root causes of poor quality from production processes so that the organisation, its staff and its products are moving towards perfection. This relentless pursuit of perfection is a key attitude of an organisation that is "going for lean".

Continually making improvements to further eliminate waste and add value is critical in order to perfect your lean construction processes. Not only should adjustments be made throughout the individual project to identify and reduce waste but taking what you learn from project to project will allow you to continually innovate new ways to add value and eliminate waste

If we constantly strive for perfection through incremental continuous improvement we will not only increase our quality, solve more problems and improve our outputs but most importantly, in time it will lead to improved customer satisfaction and ultimately greater customer retention.

[edit] Summary

In summary any organisation trying to successfully implement a lean construction environment will first need to make a significant effort to shift away from the fire-fighting culture we tend to see in the industry. To do this will require strong leadership, a commitment from senior management and support from the functional leads across the projects as well as adequate time being given for education and training in the benefits of ‘lean’.

Lean isn’t just for a few specially skilled team members It applies to everyone as part of their everyday work. Only once this cultural shift has begun, through engagement, education and encouragement will we start to see a workforce that feels empowered, collaborates, problem solves and challenges what they do on a day to day basis to make it more effective and efficient.

If we all look to continually improve how we work, we will deliver the 5 core principles to increase the value we produce, improve processes and delight our customers in a safe and successful way.

[edit] A final word of warning

To understand the value stream, we must consider the process as a whole. It is not uncommon for phrases such as ‘streamline the process’ or ‘it is not lean’ to be banded about and used to support a change to process without a true reflection of the value generated. Unfortunately, construction is an extremely fragmented industry meaning we often work in functional or organisational silos. Individual functions or organisations bring about what is believed to be an improvement to the process without considering the true consequences. This can result in unintended consequences which cause detrimental effects further down the line. It is vital techniques such as those described above are utilised properly. It is strongly recommended analysis of processes are supported by quality specialists who have appropriate knowledge and experience of lean tools and can facilitate a suitably robust and thorough review.

Sometimes, when true value is considered you may actually end up ADDING steps to a process not removing them because this benefits value overall.

The term ‘value engineering’ is often used and tragically, rather than a true analysis of value, focus is placed on perceived ‘wastes’ resulting in what is nothing more than a ‘cost cutting’ exercise. Ultimately, this creates more waste rather than less long term.

Original article written by Stuart Anwyl and reviewed by Jon Adshead on behalf of the Chartered Quality Institute's Construction Special Interest Group, and accepted for publication by the Competency Working Group on 20th March, 2021.

--ConSIG CWG 17:58, 20 Mar 2021 (BST)

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