From the original architects' point of view, maybe the only remotely possible way to have allowed for such a perspective (disregarding the problem of motion) would have been to eliminate the darkness below using some form of illumination, and then taking enormous pains to match--in texture as well as proportion--the exposed bottom of the chasm to the top surface of the bridge. In other words you would need to make it all rocks and no darkness in order to be even the least bit plausible.
Of course being able to see the bottom would rather mitigate the dramatic effect of the Step of Faith. It might even turn the Step of Faith into the Spelunk or Rock Climb of About the Usual Degree of Courage Such Ventures Normally Require, Give or Take. Just go down one way and come up the other. (Not necessarily Indy, who is pressed for time, but maybe some other adventurer whose father is not dying.)
But of course they did not choose to do any such thing. And given the incredible effort and time and possible defiance of physics it all would have involved, we might say they chose...wisely.
Edited by du Garbandier, 07 August 2009 - 01:04 PM.