The interchange is just the overlapping of two highways. There is a trailer underneath the overlap with some ammo crates inside. Numerous deathclaws inhabit the area.
Entering the backside of the ruined trailer or walking past the trailer will cause a deathclaw to spawn or jump down on top of the trailer. However, there is a large cache of high-end ammo types, ranging from 9mm Hollow point to .50 MG incendiary, in the two ammo crates at the back of the trailer.