If you need to know how to calculate the distance between two or more geocoded addresses this is how you do it. For example, if you wanted to create a table with the driving distances from a number of patients to a hospital. This is intended for a many-to-one relationship but it can be done with a many to many I believe.
This is the way I figured out how to do it. I am sure there are other ways.
I have only gone through these instructions once. All standard disclaimers apply. Your milage may vary.
Please feel free to pass it on to others who need and also to make any corrections. However, please let me know about the corrections so that I can correct it in my copy.