How does an automatic road barrier decide when a vehicle is coming?
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?
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."
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.
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.
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.