# Traffic Light Logic

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### #1 petrushkagoogol

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Posted 13 November 2017 - 06:10 AM

Traffic lights use the same colors in the same order across all nations.

The colors are -
Red - Primary color - Stop (1)
Green - Primary color - Go (3)
Yellow / Amber - Secondary (Red + Green) - Wait (2)

These seem to define the acceleration pattern of a motor vehicle.

Is there some clear logic in the implementation of traffic lights ? Primary colors red and green are used to symbolize no motion and complete motion. The mixture of the two i.e. yellow / amber formed by combining red and green is used to symbolize the wait (intermediate state).

Do you agree ?

### #2 pzkpfw

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Posted 13 November 2017 - 11:48 AM

Amber doesn't mean "wait" here, it means "stop (if you can do so safely)".

Other than that, you're doing your usual over-thinking, looking for a deep meaning underlying something simple.

http://www.todayifou...traffic-lights/

Edited by pzkpfw, 13 November 2017 - 11:51 AM.

### #3 Buffy

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Posted 13 November 2017 - 07:37 PM

Amber doesn't mean "wait" here, it means "stop (if you can do so safely)".

Actually in California, amber means "go like hell because the light's about to turn red"...

If everything seems under control, you're just not going fast enough,

Buffy

### #4 petrushkagoogol

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Posted 14 November 2017 - 04:22 AM

Amber doesn't mean "wait" here, it means "stop (if you can do so safely)".

Other than that, you're doing your usual over-thinking, looking for a deep meaning underlying something simple.

http://www.todayifou...traffic-lights/

Wavelength of the colors based on their sequences in the visible spectrum seems to play a key role here ......

Refer to this  : https://www.thrillis...-colors-history

Red has the longest wavelength, green the least and yellow which falls mid-way between the two (and is composed of a mixture of the rwo) has an intermediate wavelength.

### #5 exchemist

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Posted 14 November 2017 - 10:35 AM

Wavelength of the colors based on their sequences in the visible spectrum seems to play a key role here ......

Refer to this  : https://www.thrillis...-colors-history

Red has the longest wavelength, green the least and yellow which falls mid-way between the two (and is composed of a mixture of the rwo) has an intermediate wavelength.

It is a common misconception that mixing red and green light makes light of an intermediate wavelength. It doesn't.

We have receptors for red and green and the light we see as yellow is simply light that stimulates the red and green receptors equally. This can be achieved either by light of an intermediate wavelength or by a mixture of equal amounts of red and green light. But a spectrometer will soon tell the difference between these two, even if they appear identical to the eye.

### #6 pzkpfw

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Posted 14 November 2017 - 12:12 PM

Wavelength of the colors based on their sequences in the visible spectrum seems to play a key role here ......

Refer to this  : https://www.thrillis...-colors-history

Red has the longest wavelength, green the least and yellow which falls mid-way between the two (and is composed of a mixture of the rwo) has an intermediate wavelength.

Yep, no particularly deep meaning there.

### #7 Deepwater6

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Posted 15 November 2017 - 07:36 PM

At the water plants I manage we are in the process of upgrading all of our PLC's. The SCADA systems give operators status on hundreds of operations at the plants. I came up through the ranks and for the 25yrs or so I've been looking at certain colors to indicate status. The old system showed a piece of equipment displaying "red" meant running, "green" for off, and magenta for failure status.

The IT guys are changing these colors to get closer in line with the industry. The new system has the equipment running represented as "green", no color or grayed out as off, and magenta for failure.

After looking at the same colors for many years myself and the older operators and are experiencing confusion with the color changes. Being used to green meaning "off" and red meaning "run" this switch is causing considerable issues and delays.

Much like many other pieces of technology I wish everything had consistency from the start. My biggest aggravations along these lines is no commonality among charging cords. The unique cords for different phones, cameras and a slew of other devices that must be charged. Although I read a few month's ago that some companies will be coming out or have found a way with a wireless charging device and will deploy them soon. Oh Mr. Telsa, where are you? we need your vision now more than ever.

### #8 pzkpfw

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Posted 15 November 2017 - 07:48 PM

At the water plants I manage we are in the process of upgrading all of our PLC's. The SCADA systems give operators status on hundreds of operations at the plants. I came up through the ranks and for the 25yrs or so I've been looking at certain colors to indicate status. The old system showed a piece of equipment displaying "red" meant running, "green" for off, and magenta for failure status.

The IT guys are changing these colors to get closer in line with the industry. The new system has the equipment running represented as "green", no color or grayed out as off, and magenta for failure.

After looking at the same colors for many years myself and the older operators and are experiencing confusion with the color changes. Being used to green meaning "off" and red meaning "run" this switch is causing considerable issues and delays.

Much like many other pieces of technology I wish everything had consistency from the start. My biggest aggravations along these lines is no commonality among charging cords. The unique cords for different phones, cameras and a slew of other devices that must be charged. Although I read a few month's ago that some companies will be coming out or have found a way with a wireless charging device and will deploy them soon. Oh Mr. Telsa, where are you? we need your vision now more than ever.

I used to do SCADA programming; some of it for a water treatment plant, and an irrigation system, among others. For the irrigation system (pumps from a river up to a water tank on a hill, shared by local farmers) I was proud of how cleverly I'd made sure all the pumps got equal time even though the flow rate required at any one time could vary.

The district council engineers said something along the lines of "Dummy! That means they'll all need servicing at the same time, and they'll all wear out and need replacing at the same time, and that'll kill the budget". Oops. Obvious in hindsight.

Standardisation in UI's - that'll get me ranting about Windows 10, so I'll stop right now. (Expect to say "give me my visual affordances!").

Commonality in chargers has been approaching for a few years now. The EU even passed a law about it. Most stuff you get today will take a micro USB at 5V.

Wireless charging has been a round a while too, but commonality among devices may not be here yet. I do use a wireless charger on my own (Nexus 4) phone; a generic no-name brand thing I got cheap.

Tesla did some good stuff, but was also 50% crank. There's nothing he'd come up with today that would be new. There's been a few years since he did his good things.

### #9 Deepwater6

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Posted 15 November 2017 - 10:41 PM

Clever programing can extend the life of a lot of equipment. It can avoid short cycling and help distribute run time. Depending on the process we have some set up for lead and lag starts, alternating starts, and speed control through variable frequency drives.

Although VFD's are expensive they can make equipment last much longer. Some of our pumps are large 2000+HP. Those pumps are designed to run and run and run. The fewer stop/starts they have the longer we can extend the life of the motor. These pumps are powered by 4160v breakers, and bouncing them on and off doesn't do them or our grid much justice.

### #10 Farming guy

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Posted 16 November 2017 - 04:57 PM

Clever programing can extend the life of a lot of equipment. It can avoid short cycling and help distribute run time. Depending on the process we have some set up for lead and lag starts, alternating starts, and speed control through variable frequency drives.

Although VFD's are expensive they can make equipment last much longer. Some of our pumps are large 2000+HP. Those pumps are designed to run and run and run. The fewer stop/starts they have the longer we can extend the life of the motor. These pumps are powered by 4160v breakers, and bouncing them on and off doesn't do them or our grid much justice.

There is also the advantage using only as much power as you need when you need it.  It's similar to our vacuum system for milking cows.  Our old system would run at full speed all the time and vacuum was set  manually with an intake valve and a nearby pressure gauge.  The newer system has a sensor that measures vacuum and maintains it by adjusting the speed of the electric motor.

As for traffic lights, I am reminded of driving through a city in a snowstorm.  I knew I wanted to avoid stopping and starting, so I maintained a constant, relatively slow speed, never had to touch my brakes or shift gears, and every traffic light I had to go through was green when I arrived.  Some yahoo in the next lane over was in a hurry and ended up almost losing control at each light, and I actually ended up getting through the city in less time

### #11 Buffy

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Posted 20 November 2017 - 11:00 AM

I knew I wanted to avoid stopping and starting, so I maintained a constant, relatively slow speed, never had to touch my brakes or shift gears, and every traffic light I had to go through was green when I arrived.  Some yahoo in the next lane over was in a hurry and ended up almost losing control at each light, and I actually ended up getting through the city in less time

Note though, that this is really difficult to engineer in dense grids. One street will be set up that way, and the next street over, because of the interactions on the grid as far as timings go, will be a nightmare.

Any time spent driving in Manhattan, (or riding in a cab at rush hour) demonstrates it pretty well. I did some simulations of this based on conversations I've had with NYC cab drivers, and there's really no good solution there....

Americans will put up with anything provided it doesn't block traffic,

Buffy

### #12 Farming guy

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Posted 20 November 2017 - 12:11 PM

Any time spent driving in Manhattan, (or riding in a cab at rush hour) demonstrates it pretty well. I did some simulations of this based on conversations I've had with NYC cab drivers, and there's really no good solution there....

The last time I drove in Manhattan, I arrived at around 2:00 in the afternoon and parked somewhere in the neighborhood of Grant's tomb and a relative who lived in the city acted as my guide when navigating the public transportation system, which I enjoyed.  When I left, I left around 4:30 in the morning and found the traffic to be a delight at that hour!