I’ve found that an important first step in understanding an analtyics or optimization problem is to visualize its scope and try to make the numbers meaningful.

I was researching the coal industry to get some realistic numbers for a case study in our new book, Supply Chain Network Design. It turns out that the US mining industry pulls slightly over 1 billion short tons of coal out of the earth in 2010. A short ton is 2,000 pounds.

Well, 1 billion is large number, but I wasn’t sure how large.

Here are my top 5 ways to visualize (without graphing) 1 billion tons of coal:

**10,800,000 rail cars**. Still a large number. Not sure this helps, but this allows us to start to understand the logistics in moving the coal from the mines to consumption points.**297 unit trains per day, every day**. A unit train is a typical coal train with about 100 cars. That is a lot of trains, but a number we can start to visualize.**5 1/2 hours per day watching unit trains roll by.**So, if you are stopped at a RR Crossing and those 297 unit trains start rolling by, it would take 5 1/2 hours for those trains to roll by. Since a unit train is about 1 mile, another way to think about this one is that this train would stretch from the top of Indiana to the bottom along I-65 (actually it would be little longer than this, but this is close).**260 Louisiana Superdomes**. If we put all the coal into the Louisiana Superdome, we would need 260 of those structures. This converts the coal to space verses a rail car.**A 5x5x5 box of coal for every person in the US**. Before I did this, I would haven’t been able to say whether the coal burned per person would fill up a box, a room, or a house. A box about 5 feet by 5 by 5 is a big box, but just a box. (Remember, if you have a family of 4, you need four of these boxes).