- The line at the security check point really is just like the lead-time for a manufacturing order.
- Lean manufacturing is based largely on the idea that we should reduce inventory and lead-times.
- Lines occur because of two things: a limited capacity and variability in the process.
- Adding increased capacity – and living with lower capacity utilization -- can reduce the average line length.
- The X-ray is typically the bottleneck in the security checkpoint and simple improvements can keep that resource operating with the best utilization.
As a consultant in supply chain management, I travel a lot. One of the joys of modern travel is going through airport security. As you may have noticed, getting through security is not always the fastest thing to do. As I wait in those lines, wondering if I am going to miss my flight, I can’t help but fantasize about… material lead-time.
Yes, I can’t shake my operational roots. And really, equating the Transportation Security Administration line with lead-times is a good analogy. All processing networks can be modeled with similar mathematics and they all demonstrate similar dynamics. The line at the security check point really is just like the lead-time for a manufacturing order, or the wait time on hold with a call center, or the packet buffer in an internet router. When I am in a line, I just imagine that we travelers (pun intended) are all work orders in the factory waiting to be processed. Nice little batches of work-in-process on the shop floor, watching our fellow production jobs go, first-in, first-out, into the manufacturing line that is the X-ray machine.
But these thoughts of lead-times and production jobs are not always as happy and comforting as they sound (what, the manufacturing floor is not comforting to you?). As I look at the lines, I think the same thing I think when I see lead-times: Why are they so damn long?
Manufacturing and supply chain professionals have been conditioned (by years of quarterly beatings from our superiors) that lead-times and the associated inventory are bad, bad, bad. Entire philosophies of manufacturing, such as Lean, Six Sigma, the Toyota Production System and Just-In-Time are based largely on the idea that we should reduce inventory and lead-times. Some days, both on the job as an operations professional, and waiting in the TSA line, it feels like all this good knowledge on reducing lead-time isn’t being put into practice.
Here are a few concepts about lead-time dynamics that might help the TSA. For my readers who are manufacturing and supply chain professionals, every time you see “line” or “wait time” below, just think of your lead-time or buffer stock, and you can apply the same learning. Of course, I have to add the huge caveat that I am only addressing the queuing dynamics of the security lines. The TSA personnel are professionals whose primary function is security and protecting us from those who would do harm. In that regard, they have only my appreciation and respect. But about those lines…
