Two passenger trains 220 miles apart are headed toward each

Two passenger trains 220 miles apart are headed toward each other on the same track—one at 50 mph and the other at 60 mph. Ironman responds to the danger by flying back and forth between the trains, hoping to stop them before disaster strikes. Unfortunately, when he reaches each train, an invisible force repulses him back, jolting him in the opposite direction (toward the other train). If Ironman maintains a constant speed of 150 mph the entire time—while flying back and forth between the trains—how far will he have flown when the trains collide?