A building has 30 storeys above the ground floor. The typical floor height is 3.5 m. A car lift has a capacity of 16 persons and its speed is 3 m/s. The width of the lift car door is 1.2 m with a door opening speed of 0.6 m/s. Assume 2 seconds as the transfer time for each passenger. What is the round-trip time of the car lift?