This is a strange collapse. The edge of the bridge with the concrete wall railing on it broke off
https://www.wsbtv.com/news/local/bridge-collapses-on-i-75-in-chattanooga-interstate-closed-in-both-directions/936050582 (https://www.wsbtv.com/news/local/bridge-collapses-on-i-75-in-chattanooga-interstate-closed-in-both-directions/936050582)
Discussion had begun on the Bridges board...Not sure if here or there is more appropriate
https://www.aaroads.com/forum/index.php?topic=24778.0