The Goal

I was standing in the line at Subway today. The guy in front of me placed his order but was unable to move down the line because of a backup somewhere in the toppings portion of the line. So, the order-taker had me shout my order over the shoulder of the guy in front of me. After that, he asked the guy behind me to shout out his order. To be honest, I was uncomfortable shouting out my order over someone else. I don't want people to know what I'm ordering (Can you believe that guy wants Tuna with Pepper Jack? What a loser.).

I would expect this kind of thing at Original Ray's Pizza in New York. But a corporate beheamoth like Subway should be a highly-tuned sandwich making machine. I read a book called The Goal which is a fictional account of a guy who is put in charge of a failing factory. With the help of an old college professor, he figures out how to overcome the plant's problem with inventory among other things. One of the key messages in the book is the importance of identifying and eliminating bottlenecks.

Clearly in Subway's case, there was a bottleneck in the sandwich production process. Having visited this Subway about 200 times so far this year, I've noticed that sometimes, the Toasting Oven has a backlog of sandwiches. This means that people can't proceed forward in line until the sandwiches are finished being toasted. So, why does the order taker continue taking orders if there is a backlog of untoasted sandwiches? That's precisely my point! He's basically adding work-in-process inventory for no reason.

I think he keeps adding inventory because, once the oven is ready for a new batch of sandwiches, he is prepared to stuff in as many sandwiches as possible. Makes sense from his perspective I guess. But after the oven is emptied, the people at the toppings station are overwhelmed by all of the freshly toasted sandwiches. There are only two sandwiches that can be processed at the same time in the toppings station. So, if four sandwiches come out of the oven, two will be waiting in the queue.

The bottom line is, Subway has some problems with their assembly line. I would at least suggest that they use a conveyor belt style oven instead of the closed door style they currently operate. This way you don't have to wait for one batch of sandwiches to be done before starting a new batch. This won't completely eliminate the oven as a bottleneck, but over time should make the process flow more smoothly. Also I think that adding a third toppings station would be beneficial. Lastly, they need to have a roving sandwich maker that can help with either toppings or initial sandwich creation as needed.

However, these suggestions need to be weighed against additional fixed and variable costs (the new oven and the addition of a rover). Furthermore, the store is space constrained and it is unlikely that it could be reconfigured to add a third toppings station. But they may be able to add an additional bin for the two most popular toppings--lettuce and tomato. If placed centrally, a third topping worker could share the other toppings on his/her left and right with the other topping workers.

The end result will be that I can get my sandwich during the lunch rush more quickly and without having to shout my order over the backs of other people.