Every once in a while someone picks the scab that is "Why did Road Atlanta get ride of The Dip?" And more hilarity ensures.
Quick summary: built in 1969 with its first race in 1970, Road Atlanta is a racetrack just northeast of its eponymous city. It's a rockin' great race track, filled with excellent elevation changes, fast sweeping corners, and is a challenge both technically and emotionally. It's truly one of this country's jewels and is one of my "most favoritest" tracks in the USA (others being with similar challenges such as VIR, Watkins Glen, and Road America).
Its signature portion Back When was "The Dip" or "The Gravity Cavity", a deep drop downhill into a valley/cavity which suddenly changed to a steep rise on its other side, dumping you into an off-camber turn over another hilltop and under an infield-access bridge, down another hill on the other side to another sweeping turn that shot you down the front straight. It was as roller-coastery as you can ever get without being attached to some rails, certainly as you can everget in a race car, and was adored by any racers that dared challenge it.
Sadly, in 1996 the track was purchased by Don Panoz, a pharma wiz that developed the trans-dermal patch. In order to bring the track up to FIA standards and make it a more-attractive venue for bigger events, Panoz had the track reconfigured. He bridged the track over the Dip, using the area under that new bridge as an access tunnel for competitors to access a new paddock that was carved into the hillside on the infield side of the track along the front straight.
Along with losing the elevation thrill of The Gravity Cavity, Panoz removing the sweeping fast corners by creating a tight left-right chicane at the end of the long back straight, leading up to the original bridge. Doing this emasculated one of (if not "the") signature characteristics of the track.
Ever since the demise of The Dip, drifers who drove it regularly complain about it. Hell, I've complained about it myself from time to time, pretty much thinking that Don Panoz (R.I.P. 2018) has likely had to justify this desecration with St Peter himself.
But what's done is done, and shall never go back. But why do that? Why take such a signature portion of a signature venue and destroy it? Surely Panoz didn't take doing this lightly?
Go to Google Maps and check out satellite view of the track. Road Atlanta seemingly appears in the middle of nowhere, Georgia; in the 80s and 90s it actually was. But where Road Atlanta used to be in agriculture country (there was a chicken farm within "nose-sight" of the track) it's now becoming swallowed by Metro Atlanta suburbia.
Panoz had to do something to get big events there, the kind of something that would bring in big crowds; after all, no major venue can survive long without bringing in big gate money with spectator events. That answer was FIA-sanctioned events, with FIA-sanctioned cars, crews, and equipment (read: many tractor trailers). I'm convinced that the decision was absolutely not taken lightly, and the over-riding reason that The Dip was covered up was to bring these big events to Road Atlanta.
The advnatages of doing so were two-fold, paddock access and safety.
The original paddock wasn't up to bringing in major sanctioning bodies, which bring in many tractor trailers. I remember in the old days of the SCCA Runoffs there (a long time before amateur racers were arriving in tractor trailers) paddocking was a Tetris experiment. Most of us not only weren't on pavement, we were, literally, paddocked out in the weeds (I usually ended up in the kudzu...hell, one year we parked our open trailer near the fringe of the kudzu, and a week later we had to machete it out of there.)
If you were planning to carve back the hill overlooking the front straight to install a new paddock, how would you get the trucks over there? You're not going to send them over that small T11 bridge, as it's too tight and would likely require re-engineering/replacing that bridge. Plus, it would create a lot of conflicting traffic with spectators.
I suppose you could have brought trucks in via the old Howington Road access, but I don't know if RA still owns that property. Or maybe through the new area that was created to the east/northeast (behind Turn 1 where the companies are now). But you'd still need to build a bridge/tunnel across the track at T1 for either.
Or...you can cross The Dip as an access road to the infield, and raise the track over it with an above-grade bridge. By doing those changes it would provide tractor-trailer access to the new necessary inner paddock.
As for safety, I don't recall a lot of complaints about safety of the track back in the day. I do recall a lot of awe describing the thrill of it. I loved it. We did lose an SCCA member there one year, but that was an open-wheel incident, and then there was that terrible movie filmed afterward where a car launched and crashed into the span of the bridge (a movie so bad, that I can't even remember the name of it).
By the same token, I don't recall a lot of complaints about racing without certified closed-face helmets, fire suits, and head and neck restraints. but we require them today. Regardless, that, what?, mile-long back straight was now funneling into an eye-of-the-needle slot under the T11 Bridge, now without the hill to help slow you down, where right after it was an off-camber downhill turn right into a wall. The speed you would have carried through there would have been incredible. I'm guessing the major sanctioning bodies said, "nope", so something had to be done.
So need for more paddock space results in changes ot the track that make it even more dangerous, which results in a "gotta slow you down" chicane. I'd suggest that, but for the need for the inner paddock, The Dip would still exist.
If you want to touch the old Dip, just walk over to the truck access tunnel; the floor of the tunnel is the bottom of the old Dip. Then you can look up at the current track and imagine just how much of an elevation that was...at 125mph, plus.
I've raced both configs and do miss the old one. But I'd rather have Road Atlanta there in today's config, than having it replaced by another subdivision (RIP, Texas World Speedway, Riverside, Ontario, ad nausea).
Get there and drive it while you can.
Edit: if you'd like to see what The Dip looked like, here's some old in-car VHS video I converted from the 1991 Runoffs. It's crappy quality, but...it was 1991.