Not knowing what your layout looks like or how you plan to operate, why not just put together one passenger train at Terminal A and run it to Terminal B. Then reverse the train (in any manner you choose) at Terminal B and run it back to Terminal A. Do all of this under a stopwatch, but at an easy pace, and compare the results to what you think the real world time for those activities would be. You now have a "fast-clock" ratio that should work well for you and your layout operation.
Chuck