HI, Its been a while since I took my then toddler, now 5 years old, on the train but we used to do it a lot before we moved to far north and we would take the train to the zoo. but we found that the best train car to ride in is the first (front) train car. the driver is on that car and the people who might beg you for money wont get on that car and bother you.
before we realized this, we would get approached by some riders who would sit behind you and then ask you for money and it was scary because you are trapped on that car and we were scared they would freak out if we said no...
but there are dart cops who ride the trains and the beggers will get off when they see them but its best just to ride in the front car then you wont have to worry about that because they know the driver of the train is there and can call for help if there is a need.
I dont mean to sound scary it was a great way to ride in general but there are slow times of the day when the cars are less crowded that we found that this type of thing would happen.
but the dart train takes you right to the dallas zoo and that was fun!
HTH
A. J