Escape hatch question

Does anyone know the minimum size and clearance requirements for an escape hatch?

I found the minimum size it's 400 mm or roughly 15 3/4". How do you define free and clear? Is 28" acceptable?

A17.1-2016-2.14.1.5.1, states that for a passenger elevator. The exit shall be able to allow the unobstructed passage of a pipe measuring, 12"x20"x59" at an angle of not less than 60 degrees from horizontal. There needs to be clearance 42" above the opening. That is what the code reads. Leave it to an engineer to come up with something like this.

I'll put up some white and red tape then.