If the bus took off from a flat surface and tried to land on another flat surface the same height, as it appears to in the film, it would not have been possible. The bus would have fallen 2.27m and crashed into the raised freeway. Nasty!

Bus with no ramp:

To clear the 50ft gap on the freeway, what is needed is a jump (an angled surface) So why is this and what angle is required? If we take an angle of, say, 30 degrees, then travelling at 75mph the bus will start with an initial upwards velocity (speed in certain direction). What would the upwards (vertical) and horizontal velocities be?

Bus with ramp: