What do a MRT / Subway driver do when he suddenly has an unbearable stomachache whilst operating the train?

Question

Given that there's only himself operating the train, and no toilet on board, what actions do a train driver normally takes?

Answer 1

he will call the controll office and he will stop the train at the next station he will get off and another driver will take his place

Answer 2

He enjoys the privacy in his cab, I am worried about you riding rough weather.