It's the same train, traveling at the same speed, around the same track. 80 Minutes being equal in time to 1 hour 20 Minutes. The same train makes the trek 12:00-1:20 ; 1:20-2:40 ; 2:40-4:00 ; 4:00-5:20. It's the same train, therefore it takes the same time 80 Minutes or 1 hour 20 Minutes. as stated.