Transportation waste is the unnecessary movement of parts, double-handling of materials, or shuffling of inventory to get access to the right components. Transportation waste is one of the seven wastes that Taiichi Ohno identified as barriers to flow.
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It is obvious why moving parts further than necessary is wasteful. Transportation takes time. There is also the frequently overlooked fact that people often have to make round trips, adding to the delay. It is surprising how far people walk in the course of a year in many processes. Walking 100 feet to get parts 20 times a day can add up to nearly 170 miles a year.
The need to transport parts also drives inventory up, creates a need for space to store those parts, and uses energy for more forklift time and warehouse heating. The list of additional waste generated by transportation goes on and on.
Transportation waste stems from poor factory layout and large batchsizes. When processes are not close to each other, parts need to be transported. Batches tend to come from big, multi-function machines that serve many product lines. These large machines are one of the drivers of poor layout.
Shared machines are also a culprit of transportation waste. This is especially prevalent in offices where printers and copiers are shared. In an extreme example, I observed a groove in the floor where people had worn a trough by walking back and forth across the hall to make copies over the years.
Eliminating this waste requires a focus on flow. When parts move directly from one process to an adjacent one, the distance travelled is minimal. Reducing batch size through SMED and designing product oriented work cells are both good methods of reducing transportation waste. Switching to right-sized machines also helps limit transportation.
One word of caution about transportation waste: it often doesn’t seem wasteful when a factory’s layout is not viewed as a problem. If functional cells are considered good business, transportation between those cells seems like a necessary task.