URGENT! Creating a directional sinusoidal roof surface

Hi, I am attempting to recreate the Southern Cross station in grasshopper, and am having trouble figuring out the roof formation. I have attached below my Grasshopper script and attempted to make a trapezoid form (like the cross stations plan) and attach a sine expression to create the wave of the surface. I find that no matter how I change it up it doesn’t resemble the actual roof and would love some advice on how to go about correctly creating it.

Souther Cross Station.gh (16.5 KB)