Bottlenecks & Constraints
Bottlenecks are the point where a path restricts flow. Constraints are restrictions or limitations in the system.
The bottleneck, aptly named after a bottle’s neck, restricts liquid flow. In practice, it is the spot where congestion appears and is fixable.
On the other hand, constraints cannot be removed from the system. A project’s set cost or scope are limiting factors.
Why Use It
Every system has points where congestion occurs and delays production.
The weakest link is the bottleneck, which causes the most friction in the process. A system’s output is determined by it, and the negative impact can be outsized. However, it can illuminate new ways forward and allow creative thinking around potential solutions once identified.
Improvements that do not address the congested area won’t make a material difference.
Conversely, constraints are a given set of criteria to successfully see a project to fruition. A novel might have a minimum or maximum word count to be publishable. If you’re building a skyscraper, it could be regulations.
When to Use It
Discovering where bottlenecks exist is a matter of noticing where lines are forming.
Some examples of where congestion occurs:
- Inventory piling up.
- Backlogged work.
- Information and communication breakdowns.
- Customers are lining up for something.
An example of this at home is a slow WiFi router on a high bandwidth network. Regardless of the network’s potential, the router cannot utilize it, resulting in poor service to the household. Buying a wi-fi extender to boost the signal won’t fix the root cause — the router bottleneck.
When it comes to work, a bottleneck can often be a person who owns a process, and for whatever reason, cannot meet others’ needs. It can result from poor management or be reflective of under-resourcing.
Alleviating a bottleneck can shed light on other weak points. A system will always have places where slowdowns occur and need constant improvement.
A constraint can be mistaken for a bottleneck but is a fundamental parameter of the project:
- The scope is a set of requirements based on an agreed-upon document.
- The budget is a limit set on the work.
- The schedule is a deadline imposed by stakeholders.
- Quality standards must be met for a given output.
Distinguishing the bottleneck from the constraint is essential in evaluating and guiding a solution.
How to Use It
Bottlenecks will exist in any system, and once solved, another will invariably take its place.
Identifying and resolving a bottleneck requires understanding what else might occur in the system. If a problem area is fixed but causes worse effects downstream, then you’ve negatively impacted the process. Bottlenecks should exist in the least disruptive spot.
One tricky part in the discovery process can be probing for false narratives. For example, someone can’t complete their work without an approval step, but it still does not get completed once removed. The bottleneck was falsely identified as an approval step but hinged on something else.
When other parts of the system are improved, but the weakest link stays the same, it will cause even more stress on that part of the process, exacerbating the problem.
There are a few solutions for a bottleneck:
- Reimagining a part of the system and changing the current process.
- Adding more resources to the same approach to improve throughput.
- Decreasing the input by reallocating functions upstream.
Anticipating bottlenecks while solving the current one is imperative, as updates will redistribute stressors. A busy subway line might need more cars, but in adding capacity, those travelers find themselves waiting for another train on a different line elsewhere in their commute.
How to Misuse It
Correctly defining a bottleneck versus a constraint is necessary. Fixing a bottleneck is not enough if it makes a process worse elsewhere, and understanding the consequences of a change will ensure the correct problems are solved.
Discovering bottlenecks can lead to new and better systems. What blockages are in your own life? Where can you fix a process that desperately needs to be updated?
Think about personal and professional bottlenecks that could be changed, think through any false narratives, and deliver permanent solutions.
Where it Came From
The term bottleneck was coined in 1896 to describe where anything obstructs a flow. Eliyahu Goldratt describes his theory of constraints in his 1984 book title “The Goal.”
What Are Mental Models?
Mental models are thinking tools that help guide and shape our perceptions of the world. They simplify complexity so we can understand life better, make decisions confidently, and solve problems.