How does an automatic road barrier decide when a vehicle is coming? - eviltoast

So just something that’s been on my mind. At my workplace there’s an automatic road barrier that lifts up and down when vehicles arrive. However, it’s not used for a carpark system when people wave their tickets or something. It just goes up and down when a vehicle shows up.

However, it sometimes goes up for when say a pushcart is being rolled over whereas it wouldn’t for a guy pushing a bin.

So tldr, how does an automatic road barrier decide that yes, a vehicle is coming, and therefore opens up?

  • atlasraven31@lemm.ee
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    1 year ago

    Same as traffic lights. “Inductive-loop traffic detectors use an electrically conducting loop embedded in the pavement to send a signal to the traffic control system to indicate the presence of a vehicle.”

    • Narc082@aussie.zone
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      1 year ago

      This, it’s like a metal detector but, bigger. Temporary boom gates might use infrared motion sensors like automatic lights. edit: “lights” like the lights some people have on their porch.

      • TWeaK@lemm.ee
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        1 year ago

        It’s bigger in overall structure size, but isn’t really that big itself. It’s just a wire loop, they can be installed into existing roads with minimal effort - they just dig a narrow trench and then seal it up, it doesn’t require more tarmac.

      • Tomahtoes@lemmy.world
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        1 year ago

        Check the road in front of the gate. Those loops are usually installed after the asphalt so there should be a loop patched up with tar a bit smaller than a footprint of an average car.

  • Kidplayer_666@lemm.ee
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    1 year ago

    There could be a motion sensor behind maybe? It could be one of those places that have a bunch of coils on the ground, wherein a large enough mass of metal gets detected by changing magnetic or electric fields, or something else entirely

  • FuglyDuck@lemmy.world
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    1 year ago

    Could be a lot of ways- an IR beam some where before the barrier. A motion sensor (usually IR or IR+ultrasound). Possibly some sort of movement detection on the security cameras.

    Or a magnetic loop sensor, which is my guess. (You’d see the other sensors.)