Londoners are puzzled by a blue light on Underground trains, sparking curiosity about its purpose during recent cold weather
London: Recently, folks have been noticing a weird blue light on the Underground trains. With the chilly weather, it’s caught a lot of attention, but not many know what it means.
One Londoner was curious enough to post about it on Reddit. They saw the blue light on train 032 at Hammersmith and were totally confused.
They asked, “What’s up with this blue light? I usually see it turn white when the train’s ready to go, but blue? What’s that about?”
People jumped in to help, and one person nailed it, saying, “That’s the de-icing unit in action. The train sprays de-icing fluid on the power rails.”
And they were spot on! Transport for London (TfL) confirmed that the blue light shows up on some Circle, District, Hammersmith and City, and Metropolitan trains.
When it lights up blue, it means the train is using a de-icing solution. Most people are used to seeing a white light instead.
This white light indicates that a train is about to leave, especially on lines with automatic train operation (ATO). It’s a heads-up for passengers.
On the Circle, District, Hammersmith and City, Metropolitan, and Victoria lines, a white light will shine above the windows when a train is about to depart.
If you see that white light, it’s best not to try to hop on, as the train is leaving soon, and you don’t want to get stuck in the doors.
On other lines like the Central, Jubilee, and Northern, the lights are at the platform’s end, signaling when the train is ready to go.
Just remember, a steady white light means the train is departing, and don’t confuse it with other flashing lights that might mean something else.
For lines without ATO, like the Bakerloo and Piccadilly, it’s all about listening for announcements and the door closing chime to know when to move.
