It might impale the engine, which is designed to slide underneath the cabin in case of a frontal collision.

I'd say the risk for the occupants should be similar to hitting a boulder or a tree. It all depends on the speed at impact, but given that these barriers are mainly used in urban areas I don't think they would form much of a risk.

At the sort of speeds that can be achieved in that area (Victoria) the engine might get dented. At motorway speeds it could do what you describe.

They aired some scientific tests of this question on Squidbillies a few years back: https://www.youtube.com/watch?v=92wPOsuHZ9Y