Tuesday, June 11, 2013

Cyclist runs red light

One thing that really irks me is when cyclist breaks the law. I hear every cyclist complain how cars don't respect us. Cars yell at me. Cars tell me I don't belong. Well if you want respect you need to go above and beyond to earn that respect. Ask any car driver about a cyclist and this is what they will say.

They run red lights.
They run stop signs.
They pass at lights.
They don't obey any laws.

Why do they say these things?? Well lets start with the cyclist in this video. He blows off the red light. I mean When I get there it takes about 8 seconds for the light to sense me and turn green so why did he have to run the light??

Maybe he just doesn't understand how light signals work and how to trip them. After all most people think the sensors sense weight. Well they don't sense weight the most common technique is the inductive loop. An inductive loop is simply a coil of wire embedded in the road's surface. To install the loop, they lay the asphalt and then come back and cut a groove in the asphalt with a saw. The wire is placed in the groove and sealed with a rubbery compound. You can often see these big rectangular loops cut in the pavement because the compound is obvious.

Inductive loops work by detecting a change of inductance.

So... 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 something waiting! The best type is the double loop two circles that overlap in the middle. If you put your bike right over the center it has an easier time sensing you. Oh no I said get in the middle of the road!


The video of the red light runner




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