More on the "One Trip"On Monday, I wrote about a trip to two construction sites. One worked well..the other did not. Here's more of the story, which is very instructive.
Late yesterday, I ran into a friend who is a manager at the general contractor running this site. After some pleasantries, I eased carefully into what I saw at his site on Monday afternoon; activity but no progress.
He sighed. "Yes, that's what you saw. And you know why? The concrete subcontractor only owns enough forms to set 45 lineal feet of concrete wall at a time."
Indeed. That was exactly what I saw. One end wall of the basement was about 70-80 feet long and only half of it was formed up.
This is a classic illustration of constraints. The crew I saw working aimlessly had a physical constraint limiting their ability to create value for the customer; they had a fixed amount of concrete forms. What do you do when encountering a constraint? You expoit it (have I wrung all possible out of it?), subordinate to it (do all other decisions take a back seat to maximizing the constraint?) and then elevate it (how can I get more of the constraining resource?)
In this case, my friend and I quickly got to the "elevate" question. Can we rent more forms somewhere? Can we borrow them? Can we use alternate ways to make forms? Concrete forms are not brain surgery. Can we get more, since we seem to have enough labor available to set them if we had them?
For those going deep, we might ask if there is a policy constraint sitting underneath this physical constraint. For instance, did the subcontractor have a stated or unstated rule that said "We never rent forms."? Is there some accounting policy that makes rented forms appear much more expensive than company-owned forms?
I don't know the answers to these issues. But, standing on the dusty job site on a hot August day, watching good people walk around in a deep, newly-dug basement, making no progress at all made me want to scream. This is why understanding constraints is so crucial to any Lean implementation. The constraint is where you apply the tools of lean to make the system improve. We have limited human and financial resources...let's put these limited resources to work where they matter.
Long-time readers of this blog may remember a series on Theory of Constraints that my friends Frank Patrick and Hal Macomber and I did last spring. If you find this topic interesting, start here and follow the links to learn more.
I hope this is helpful. And pay attention to the constraint. Feel free to forward to a friend. Email me