phone call to them for pulling the chain. in case you are alone and you do not have the contact number of your fellow passengers then while you are running to catch the train wave your hands to anyone who is standing at the door of the coaches or sitting inside the coaches and shout at them to pull the chain. if the train stops after chain pulling then you are out of trouble and you can board the train.
try to reach the next station : in case chain pulling exercise is not successful due to some reasons and the train leaves the platform then make a plan to reach 