BRC Imagination Arts, a Southern California design firm, has proposed something entirely new: a ride that creates the sensation of zero gravity for up to eight seconds at a time.

https://www.popsci.com/cars/article/2012-01/zero-gravity-roller-coaster

Roller coasters typically cost no more than $30 million, but Bob Rogers, BRC's founder and chief creative officer, says the zero-gravity ride would cost $50 million or more, in large part because the precision-response propulsion system is so complex. But if someone were to write a check today, Rogers says, his company could be sending riders on weightless journeys by the end of 2013

The article is from 2012, so I guess there weren't any parks willing to invest $50-million in something referred to as "the vomit-comet ride." Eek!

That article is from awhile ago; is there an update on this concept?

Oddly, no height is mentioned; doing some 5am calculations with the data provided (8s of airtime and 100mph top speed), this concept would be ~100m (320ft) tall. Probably not the prototype for what would be very new technology, but it would be cool to experience a ride with airtime on the ascent.

What a concept.   A protein spill floating in mid air, you know it’s there, and then deceleration and splat all over you.    Just because you can build something doesn’t mean you should.