Running time rule?

Is there a rule to compute running time for a particular engine/consist?
i.e. if I send a coal train to the mine, then to the powerstation and return, is there a rule that will tell me total time for the trip? Or, do I need to use that thing on my wrist?
Running times

Hi hot-box-detector,

I use the time displayed in the HUD top right of screen. i.e. finish time - start time. However when there are quite a few trainz running your coal train could be held up by a red signal sometimes so give it a little bit extra time so it does not arrive late at the powerstation. This is required if you are useing the powerstation rule, which means the powerstation will stop supplying power if it runs out of coal.

Hope this helps,
Thanks for the replies. I guess what I'm looking for is something like a running time meter on a locomotive. So, starting at point "A" running to point "B" and returning would accumulate time "X".
Calculating this trip time against the coal consumption time of the powerstation would tell me how many trains and or carloads of coal to schedule.