This post is part of a series on Queueing Theory. The other articles can be found here:

1. Queueing Theory: Part 1
2. Queueing Theory: Part 2
3. Queueing Theory: Part 3
4. Queueing Theory: Part 4
5. What is Waste?
6. On Time-Traps and Waste
7. Call Centers as Queueing Systems
8. Travel Time & Waste
9. Little’s Law for Product Development

Regarding the Physics of Queueing, or the science of lines, we really only control the number of servers and the queue discipline (LIFO, FIFO, etc.). But, in the realm of operations improvement, we can improve the process, while not being able to control the stochastic nature of the batch size and queue arrival and interarrival rates. One of the major pieces that we need to identify and eliminate immediately are time-traps.

What is a Process?
A process is an systematic activity comprising of smaller activities that culminate in an outcome — service or product. A process can take up time, space, and resources. All processes can be categorized into the following categories, from the Customer’s Perspective:

1. Value-added: This step in the process adds form, function, and value to the end product and for the customer.
2. Non-Value-Added: This step does not add form, function, or assist in the finished goods manufacturing of the product.
3. Non-Value-Added-But-Necessary: This step does not add value, but is a necessary step in the final value-added product.

For example, when a customer goes to a fastfood restaurant, their perspective is thus: they want to be (a) served the right order, (b) in the right temperature, (c) in a timely way, and (d) in a cost-effective fashion. That’s it. But, to satisfy items (a), (b), (c), and (d), there is a lot of work that goes on, some of which are value-added, non-value-added, and non-value-added-but-necessary. For example, from the customer’s point of view, (a), (b), (c), and (d) might be value added, but cleaning the stove might be non-value-added-but-necessary.

One of the non-value-added steps in any process are what we call time-traps. Time-traps are non-value-added because they require attention, time but, at the end of the day, they don’t add value from the customer’s perspective. For example, the time-trap analysis below:

The process shown above consists of several steps as displayed in the Pareto Chart. When we unpack one of the bars in the Pareto, we discover that of the total time spent in that “Packing Station” process, on average 92 seconds were spent in value-added activities while 502 seconds were spent in non-value-added activites. This means that noly 6% of the total process time was value-added.

To improve the process above and in order to increase value-added percentage from 6% to higher, a root cause analysis session was done to discover ways to eliminate the root causes for the non-value-added activities — how to reduce or eliminate them. The goal is to make any process consist of more value-added steps.

Conclusion

Time-traps are wasteful activities that reduce the value-added percentage in any given process. A goal of any operation is to discover these time-traps, then systematically reduce or eliminate them. It’s all about the customer and, from their perspective, they would prefer more value-added steps in the process, thus reducing the cost structure and increasing service level. In other words, let’s not waste the customer’s time.