That is a permanently fixed wall; it protects the main pit entrance (look further in the background).
the incident happened in the winter of 2002, at an open track day organized by Panoz racing school at RA. Remember NSXPO 2000? The Panoz school doesn't allow in-car instruction, and they permit inexperienced drivers to go round at Road Atlanta in Diablos or Civics, and everything in between. This is one of the best cases for hands-on, in car driving instruction that I know of. The caution and control an instructor brings could have prevented this incident. It was a quite simple mistake, look at the view of the skid marks. The driver went wide at the track out of '11', coming down the hill from the bridge, touched the rumble strips, lifted, and rotated, and contacted the wall. He was a new owner of the Diablo. He was OK; even the way the door is smashed in, there is a lot of integrity in the passenger compartment.