this post was submitted on 03 Sep 2025
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That's very much not what I meant. These stripes would be passive (just paint) and you couldn't really customize them because sodium or unsmoothed LED lights' flicker has a 50% or greater duty cycle, blurring any design beyond recognition.
What you're referring to are persistance-of-vision ad displays around passing trains in tunnels. These require active electronics and even accurately measuring the train's speeds.
The system in Vancouver does use electronics to create the flashing, but I'm pretty sure it just synchronises to to average speed of the train because the illusion is quite inconsistent. It will almost always scroll forwards or backwards from the rider's perspective. It probably does help that the sky train speed is controlled by a computer, leading to more consistent results.
Yup, Prague's system I know is the same as Vancouver's, possibly by the same company, but I've never seen it sync badly. The system I'm proposing are simple painted stripes, the flashing is the nature of existing lighting.
I wonder how physically resilient the LED bars in Prague are, since the windows can open enough for someone to extend a stick to damage them.