To kick us off, let’s dive into the basics on lean construction. The concept of ‘lean’ has well known origins in manufacturing, the first instance of ‘Lean thinking’ being attributed to Toyota’s industrial engineer Taiichi Ohno (along with some other founding figures of Toyota). At that time, the Toyota Production System was concerned with the reduction of ‘muda’ (or ‘wastefulness’) along their production lines, which gave rise to lean manufacturing in the United States and in turn to the practice of Lean construction as we know it today.
As for the term itself, ‘lean’ according to the Merriam-Webster definition includes the noun, “the part of meat that consists principally of lean muscle” and the adjectival application to describe something that is “containing little or no fat”. From the direct translation we get a very basic understanding of what lean production could be, but it does produce some rather narrow perspectives. Why?
Since construction and manufacturing is heavily involved with the physical or tangible environment, one might jump to the conclusion that the excess unwanted fat we aim to trim down on is material waste. And you would be correct. But in a much more real sense waste is that which does not contribute to end user value. It is a vastly complex topic and any manager worth their salt would immediately recognize how multifaceted this concept is. Waste comes in many forms, something manufacturing has spent decades identifying and reducing – Construction in todays context has a lot to learn from manufacturing and it’s adoption of lean production techniques and there has been a global shift towards construction that reduces the inherent variability of site work in favor of lean techniques. The rise of prefabrication techniques is just one example lean production adopted from constructions close relative, manufacturing.
Lean construction – it’s principles and who is at the core…
The below graphic courtesy of the Lean Construction Institute is rather interesting – it places, at it’s core, ‘respect for people’. Interesting, but also factually true. It is the respect for the people not only involved in the incredibly challenging production process that we wish to collaborate with, but also that of the end user so we can deliver the highest utility in use after the change in ownership. Being human centric, in terms of production challenges, barriers, flows and end value is at the core of Lean practices. Perhaps something traditional construction methods have strayed from and something for us to ponder – are we acting to peoples best interests or just for metric productivity and output rates?
So what is waste according to Lean Construction principles?
The first form that comes to mind is material waste. This is the most obvious, and actually quite significant to the overall project cost – it is well documented that constructions physical material waste can be as high 30%. This is a staggering figure. But if we critically analyze what exactly happens on site we can understand why it’s so high.
A recent article by Anne Fitchett of WITS university explains why this physical waste figure is so high : “The two most prevalent reasons that were cited for the causes of waste were lack of skill of labourers and subcontractors, and poor supervision. Other reasons included poor material handling, negligence, speed of execution, design changes, poor management and planning, and the normal work process. Construction workers sometimes did incorrect work, leaving waste after the incorrect work was demolished.”
It is also important to distinguish necessary ancillary inputs from waste itself – the installation and use of necessary life saving PPE does not directly add value to production, but it would be a serious misstep to consider this ‘waste’ in a Lean sense – the point of departure is that waste is excessive and unnecessary, being that which would not occur through normal skilled execution of the work. You will notice above a cited reason for waste is “… the normal work process.” , and this is to be expected and to some degree realistically acceptable.
Physical waste causes more waste
If we ponder on the materiality of construction waste, just take a second to think what other forms of waste this might cause…
You might immediately recognize that the same reasons that cause physical material waste above also cause waste of other critical project resources : time and manpower. The cited reasons for material waste of poor material planning, negligence, design changes, and rework, all demand additional provisions to produce the same output as originally intended. In the case of complete demolition and rework items, the actual cost of production is devastatingly high – the original cost now includes additional time, manpower and logistics for demolition and removal and further repeated inputs for complete or partial rework.
The bad news doesn’t end there. These are just the glaringly obvious forms of waste.
The silent productivity killers according to Lean
Let’s talk about the less obvious ‘non-value add’ activities – Back and forth communications, distribution and recalling of erroneous information, productivity downtime or rework due to clashing element or trade interfaces, poor logistics management leading to workstation starvation, stagnation and downtime. In fact there are cited sources of Lean forms of waste that include the lack of inspiring or motivating the best potential out of staff as a form of waste – if we are totally honest, this actually makes sense. It is the waste of human potential and is entirely valid. Can you think of any other ‘fringe’ forms of waste in production?
The above are to name a few of the areas we as manager are charged with optimizing and the waste in these forms is less noticeable and thus perpetuates without corrective action, but there is a cost none-the-less. The cost hurts project profitability, but in a much broader sense affects client satisfaction – the adoption of lean practices means reduced possibility of dreaded extension of time claims and generally aims for customer satisfaction in delivery and less chance of disputes.
Some typical lean construction ‘arch enemies’ inherent in every project
Inputs vs Outputs – making processes ‘leaner’
What’s interesting about the above is that we begin touching on the founding reasons for lean practices in manufacturing. Production plants studied workflows and activities to discern value add activities from ‘wasteful’ events, and the conclusion is all encompassing of production inputs, including the ‘flows’ of workplaces and the production inputs. But if we are honest we know that project and site flows regularly reach bottlenecks – all to often we see errors in material management, site logistics, handling and installation, often accompanied with challenges in information flows required to execute the work. What it ultimately means is that it can and does become a serious concern for any manager, in deciding what kind of capacity a team has to produce meaningful work within a given timeframe.
This is after all why we do what we do – something of value must be physically produced for a customer, and deadlines must be met. Where the wheels fall off is underestimating just how much waste is actually being produced on site – yes, waste is produced. (You could argue that excessive waste in todays era of information and technology is actually a choice…) And it is produced as an alternative to producing the actual value added item. Downtime is produced – we produce extended periods of non-activity. Material waste is produced – we used manpower, equipment and machinery to produce offcuts and spillage. Not sure how well this news would go down in your next site meeting! It is a matter of what you choose to produce more of (not including outcomes that are outside of our control), which comes down to you either choosing systems that perpetuate increased wasteful outputs or choosing systems that make you LEAN.
There is no end user on Earth that gets to benefit from our production of waste. And this is before we even consider the environmental, social and economic cost of waste in a broader sense. Society simply cannot afford it. Neither can your project team, tradespeople, client or end users.
So how do we reduce the production of excess waste which seems to be inextricably linked to any productive activity?
BIM as a productivity enhancer and waste reducer
So we’ve discovered waste in the broader sense, and that we are faced with choices in the outputs we prioritize. Lets discuss some mitigating strategies to the excessive waste producers and how BIM comes into play.
Firstly, BIM is founded on what I consider 2 key facts
- Construction information from various stakeholders and sources must be collated into a single source from which there can be no question regarding the completeness of the information in question.
- Construction information must be digital and thus capable of being widely and easily accessed, distributed and revised.
With the above in mind, the immediate benefit BIM offers in excessive waste elimination is that BIM is concerned with producing a complete and single source of information. The connection to Lean practices is that this allows us to ensure the effective management of information, the reduction of unnecessary and repetitive communications and the elimination of potential errors this carries – whether this is in material logistics, manpower management or scheduling. If work flows can trust that a single source of construction information is complete and accurate, a whole myriad of non-value add activities cease to threaten our Lean construction machine.
The second benefit is the digitization of construction information, and speaks somewhat to the rising trend of OpenBIM practices – We want all the requiring information readily available at your fingertips, but also easily distributed and revised. We might think this includes the physical manifestation of construction information, as printed out on site. But this is practice also that gives rise to a great many risks – everyone knows this because everyone, and I mean everyone, gets caught out once in their career for using the wrong revision. What we should strive towards is the use of digital formats up to and even including the time of actual installation at the site workspace – the practice of having heaps and heaps of construction documents, at best neatly organized in racks at the site office, is not the benchmark we should be striving for. We are seeing this on sites where a growing number of foreman now carry around mobile tablets, a progression that should become the norm.
And this is just the beginning – A 2009 study looked at the relationship between BIM and Lean, with the below matrix indicating just how closely related they are at various stages of construction. Without going into detail, the study can be found here for further reading.
Sacks, R., Koskela, L., Dave, B. and Owen, R. L. (2010), The interaction of Lean and BIM: a conceptual analysis. Journal of Construction Engineering and Management, 136 (9) 968-980.
I will end of with a quote from Einstein – ” We can’t solve problems by using the same kind of thinking we used when we created them.” With the growing awareness and trends in sustainability, I think we should all be casting a critical gaze on our personal workspaces, activities and flows, whilst seeking out novel perspectives designed to address the challenges that have ailed construction for decades – inefficiency and wastefulness.