Technically WOLO doesn't stand for anything however Warning Of Line Overheat makes a lot of sense.
WOLO boards are shown when temperatures reach approx 38°c and above.
When train tracks get to hot they can buckle or be displaced so when a WOLO board is shown there is a speed restriction for the safety of passengers.
Below is a photo of one of the WOLO boards at Blacktown on Platform 2.
Anyway folks i hope you all had a great day and stayed cool on this very hot day.
Thank you all for reading and stay tuned for more Blogs!
Phil, Sydney Trains Vlogs