I actually have one in my yard.
An RTI ramp actually. Ramp Travel Index as they used to be known.
About a decade to 15 years ago they were all the rage as vehicles developed longer travel and softer riding suspension. Spring over conversions and long travel coils. Great for tweaking suspension bits.
It keeps the over sized trees in my yard company.
The one I have is massive. We built it to withstand F350 crew cab and such vehicles. The drive up deck is 13' long and about 20" wide. expanded metal over frame. The wedge is a pivot point so that we can have it at 20 or 30 degrees. The supports are sleeved and have different pin holes so that when we raise it up, we re-pin at the greater angle.
Its fricken heavy to move. We keep tossing around ideas to make it into a trailer.
But as vehicles kept getting better and better, longer and longer travel suspension and wider and wider track widths. 13' is not all that big anymore.
So, what do you really want to know?