They are not protection girders.
The bridge on the Bhopal side is a 'Cantilever' bridge. The steel frame around the tracks is the load bearing structure and the bridge works because of the steel frame. It is not there for protection. If a derailment occurs on the bridge, these frames won't help.
The bridge on the other side, I guess, is an RCC bridge. It doesn't need the steel frames for bearing the load of the train.