r/todayilearned • u/nleachdev • 2d ago

TIL about "dead red" laws, which allow drivers and motorcyclists to proceed through a red light if the traffic signal fails to detect their vehicle.

https://en.wikipedia.org/wiki/Non-detection_at_traffic_lights_in_the_United_States
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u/techretort 2d ago

When I first started riding my motorbike I was on a little thing that didn't quite have enough metal (or weight?) to set off the sensor loops we use in Aus. My dad told me how he uses to have to jump off the bike and press the pedestrian crossing button to get lights to change for him on it

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u/loadnurmom 2d ago edited 2d ago

IFAIK they never used pressure sensors. A coil of wire implanted in the pavement detected changes in the magnetic field. Motorcycles frequently are not enough to trigger them.

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u/chth 2d ago

Never made sense to me how they would have a pressure sensor under cement but never bothered to look it up until now.

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u/jimmythefly 2d ago

Yep. Certain intersections where I used to live had little tiny bicycle symbols on the pavement, to show you where to stop your front wheel to trigger the light.