WOLO: Secret meaning of train signs appearing all over Sydney

As Sydney braces for rising temperatures that could reach almost 40C, some trains in the city will run slower to ensure safety.

The yellow WOLO signs are placed at the end of some train platforms in Sydney during extreme heat.

Authorities confirmed that when WOLO signs are installed, it will impose speed restrictions on trains as a safety measure, with speed limits above 60 km/h reduced by 10 km/h.

The yellow WOLO signs are deployed during extreme heat for trains in Sydney

Despite the speed limits, no delays are expected on Sunday and Monday.

The signs will be erected as temperatures in Sydney and Penrith are forecast to reach 32°C and 39°C respectively on Sunday.

NSW Transport Minister Jo Haylen said the WOLO signs will ensure the safety of commuters and staff and prevent damage to the rail network and infrastructure.

“It’s going to be a warm few days in Sydney, and our trains and rail will be braving the elements,” Ms Haylen said.

NSW Transport Minister Jo Haylen said the WOLO signs will ensure the safety of commuters and staff and prevent damage to the rail network and infrastructure

NSW Transport Minister Jo Haylen said the WOLO signs will ensure the safety of commuters and staff and prevent damage to the rail network and infrastructure

‘We focus on making our rail network safer and more reliable and WOLO signs play a role in this during extreme heat.

‘Traveling 10 km slower than normal can be difficult, but it takes the pressure off the track and ensures that you can enjoy the air conditioning in our train just a little longer.’

The reason for the signs is to tell drivers to drive slower, as steel tracks have the potential to expand in the heat.

The reason for the signs is to indicate to drivers to drive more slowly, as steel tracks have the potential to expand in the heat

The reason for the signs is to indicate to drivers to drive more slowly, as steel tracks have the potential to expand in the heat

The term WOLO is not an acronym, but a holdover from the days when old telegraph codes were used on the railways to communicate between offices, stations, locomotive depots and freight yards.

WOLO was the telegram code sent over the track as a condition that forced drivers to reduce their train speed in case of track that was bent or swollen under high temperatures.

This instruction made it easier for drivers to stop just before the affected track or drive safely through weak sections without derailing.

The decision to install the WOLO signs comes as the Bureau of Meteorology predicts extreme heat in some parts of the state.

Sydney’s CBD is forecast to reach 32°C on Sunday before rising to 35°C on Monday.

Beachgoers in Melbourne are pictured as temperatures soar

Beachgoers in Melbourne are pictured as temperatures soar

Those in Penrith will be sweating even more as temperatures peak at 39°C on Sunday and 38°C on Monday.

Melbourne will also see high temperatures with a high of 38°C on Sunday, before a cooler change on Monday, with 22°C forecast for the start of the week.

Brisbane will hit 32°C both days, while Adelaide will reach 36°C on Sunday but only 25°C on Monday.

Perth will see a top of 27°C on Sunday, while Canberra will reach 35°C.