The main reason for routing the standard gauge line via Koolyanobbing was so that iron ore could be moved to the coast at Kwinana. The WO class wagons were the means of shifting the iron ore. Eleven wagons were written off in 1971 but quickly replaced with new construction. And then nothing happened for 15 years. However, in 1986 conversion to other traffics started and three new classes sprang up. WOG for Gypsum, WOS for Superphosphate and WOC for Coal. Note that class WOS also included wagons formerly in class WOA. In 1994 most reverted to WO. The WOA class of thirty-nine wagons were built in 1970. In 1984 nine wagons were sent to South Australia where their bogies were hired to Australian National until March 1985. In 1986 twenty of the class were written off and "used for WHA wagons". Fourteen of the class were converted to WOAS for superphosphate traffic which was quickly changed to WOS in 1989/90 . They reverted to class WOA in 1994. Twenty five WOB class Iron ore wagons (31376 - 31400) were issued new in 1974. Fifteen were converted to WSM class ballast hoppers in 1977/8 leaving just ten in service as class WOB. They reverted to WOB Iron Ore wagons in 1997/8. Between 1969 and 1979 a total of 19 WF class flat top wagons were converted to handle Iron Ore containers WFW. By 1981 the need for this had ended and they were reclassified WFDY along with the rest of the WF class. After WAGR was sold off, two new classes (WOD and WOE) appeared in the early 2000s.