This is a NSWGR sleeper built take-off for track maintenance equipment often found alongside the main line where equipment may need to be taken off the track to allow trains to pass.
Here is a NSWGR plan showing that there should be a 1 in 40 slope away from the track to stop the equipment from rolling towards the track.
The small section of planking on the end goes between the rails so must be cut away and filed smooth where the two sprues were attached.