Transit score is part of a walk score, which is a wonderful tool for determining where a property is from vital services and places of interest, such as transit, libraries, cafes, stores, etc. For example, Berkeley - http://www.walkscore.com/CA/Berkeley - is a very walkable city. San Francisco is the 2nd most walkable city in the U.S. And, yes, in our areas rail would be both BART and Amtrak.
Just go to www.walkscore.com and put in the address of the place you're interested in and you will see businesses pop up and score tabulated.
You can also google the address you're interested in and click on "get directions" and then write in the BART station. You will get the distance and most direct route.