Hey @BobBayman, 
Thanks for your post. You would not be able to do this as a single event. Since you would have data points before getting on the train and then again when you get off the train, the activity would display a straight line across the map until the next data point begins. Unfortunately, there would be no way to remove this line other than cropping out the beginning of the ride before getting off the train. It would be best to record them as separate events to get accurate data.