It would of happened between 2003 - 2006, although it could of happened some time later, underneath the Melbourne Rd underpass over Blackshaws Rd on the freight line near Newport, not the one at Newport station. The last one or two grain cars only came off and were destroying sleepers in the middle of the track, before it came to a stop just before the rail line leaves Blackshaws Rd.
It is not this
http://www.railpage.org.au/newport_august_2003/index.htm August 2003 derailment
which I never knew about but found while looking for the one I was talking about. However it does bring up an interesting point as timeline wise I'm 99% certain the one I witnessed has to take place after that one, but the location in the second photo with the rail on its side would be the exact place the last cars had to derail for the train to come to a stop where it did, so all of a sudden these two incidents could be directly connected.
Anyone know what incident I'm talking about?