Traffic-light weight switches?

[WristTwister]

This is high school physics boys. Let's say you take a coil of wire perhaps 5 feet in diameter, containing five or six loops of wire. You cut some grooves in a road and place the coil in the grooves. You attach an inductance meter to the coil and see what the inductance of the coil is. Now you park a car over the coil and check the inductance again. The inductance will be much larger because of the large steel object positioned in the loop's magnetic field. The car parked over the coil is acting like the core of the inductor, and its presence changes the inductance of the coil.

A traffic light sensor uses the loop in that same way. It constantly tests the inductance of the loop in the road, and when the inductance rises, it knows there is a car waiting!

NOW! What most of you all seem to have overlooked is the positioning of these coils at intersections and how they reduce the visibility of a bike (look at the road code advice on positioning for visibility at intersections). I hate the funking things, and they're installed all over the "Smart Motorway"...

[Berries]

What most of you all seem to have overlooked is the positioning of these coils at intersections and how they reduce the visibility of a bike (look at the road code advice on positioning for visibility at intersections).

You've lost me. These loops are to detect vehicles approaching a set of traffic signals. What does visibility of a bike or positioning for visibility have to do with traffic signals?

[Bass]

Dont you mean that bikes are invisable to the inductive coil/sensor which is what this thread is about.? If these coils made bikes invisable there would be a lot of riders getting hit by other motorists due to the invisability field created by the coil?

At last I understand

You're Katman's evil apprentice, Supertroll, aren't you?

[rambaldi]

I doubt this is the case, I call it the elevator door theory.

Does pressing the close button when you step into an elevator actually close the doors faster? or does the act of pressing the button simply fill the gap you'd usually spend standing there wondering how much longer you'll have to wait for the doors to close.

Putting your side stand down probably fills the gap you'd spend waiting for the light to change.

The door close button does make a difference but maybe not on all lifts. At work in the back of house area we had some that due to kitchen staff trundling large trolleys and bins through was very slow to close the door. Pressing the button most definitely made a difference there.

[Dave-]

The door close button does make a difference but maybe not on all lifts. At work in the back of house area we had some that due to kitchen staff trundling large trolleys and bins through was very slow to close the door. Pressing the button most definitely made a difference there.

Clearly we need more investigation.

[rambaldi]

Clearly we need more investigation.

I think I will contribute by taking the rest of the day to ride all of the lifts around here and see what if any difference it makes.

[Moi]

Don't you mean that bikes are invisible to the inductive coil/sensor which is what this thread is about.? If these coils made bikes invisible there would be a lot of riders getting hit by other motorists due to the invisibility field created by the coil?

Do Jim Kirk, Spook, Scotty et al know this?

[Swoop]

A traffic light sensor uses the loop in that same way. It constantly tests the inductance of the loop in the road, and when the inductance rises, it knows there is a car waiting!

One small point that I have noticed in Auckland...
Asian drivers HATE stopping close to the white line. The sensors are there and they stop at least one car length back from the white line... meaning that they rarely trigger the sensor.

At least on the bike you can just ride around the Nissan Micra (mandatory vehicle type for them) and stop on top of the sensor lines.



(I had a Korean student some years ago, who swore that the lights were controlled by a human being with access to a surveillance camera)