WO type iron ore waggon WO 31224 is one of a batch of eighty six built by WAGR Midland Workshops between 1967 and March 1968 with fleet number 119 for Koolyanobbing iron ore operations, with a 75 ton and 1018 ft³ capacity, Binduli Triangle 22nd August 2010. This unit was converted to WOC for coal in 1986 till 1994 when it was re-classed back to WO.