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# Advanced Math/Traffic Lights.

Question
Dear Prof Randy

http://en.wikipedia.org/wiki/Traffic_light
http://www.engineersgarage.com/electronic-circuits/traffic-light-signal-555
http://www.555-timer-circuits.com/traffic-lights.html
http://en.wikipedia.org/wiki/Seven-segment_display

In the typical sequence of color phases:

Green Light : Illumination of the green light allows traffic to proceed in the direction denoted, if it is safe to do so

Orange Light : Illumination of the orange/amber light denoting prepare to stop short of the intersection, if it is safe to do so

Red Light : Illumination of the red signal prohibits any traffic from proceeding

Query
-----

Can a Single 7 Segment LED Display be used as an alternative
to the above three traffic lights with modifications in the control circuit ?

i.e.

0 Indicates Stop -> Similar to Red Light.
1 Indicates Stop Short Of -> Similar to Orange Light.
2 Indicates Proceed -> Similar to Green Light.

i.e. Instead of three light signals (three LED for each color red,orange and green) use of
a Single 7 Segment LED Display (indicates Number instead of colors) as source of Traffic Lights.

What are the Pros and Cons if this can be achieved ?

Do you feel showing Human Being Symbols (Red and Green Color)
would be a Bottleneck in the Single 7 Segment LED Display ?

In that Case Number 8 for Human Being Walk Stop Symbol and Number 9 for Human Being Walk Start Symbol can be used ?

The Single 7 Segment LED Color could be Blue or White with a Black
Background.

Note : The Circle Color Shape is replace with a Rectangle (7 Segment LED) Shape for this Traffic Light.

Thanks & Regards,
Prashant S Akerkar

My first impression is that changing from 3 colors to 0,1,2 would make it a little harder for drivers to respond, at least in the beginning. This, of course, is a negative attribute. My reasoning for this is simply that responding to a color requires less "cognitive processing" than interpreting a number. Neoroscinece is not my area of expertise so my reasoning is not properly informed, i.e., its just an opinion.

On the other hand, the 7 degress-of-freedom in the display could offer more information, as in your example of walk/don't walk. Note however, note that walk/don't walk symbols already exist using displays with more than 7 segnents.

Is there a reason to stick with 7-segment displays? cost, availability,...? If there is no compelling reason then i don't see an advantage overall to using a 7-segment display.

Randy
Questioner's Rating
 Rating(1-10) Knowledgeability = 10 Clarity of Response = 10 Politeness = 10 Comment Dear Prof Randy Thank you. Thanks & Regards, Prashant S Akerkar

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#### randy patton

##### Expertise

college mathematics, applied math, advanced calculus, complex analysis, linear and abstract algebra, probability theory, signal processing, undergraduate physics, physical oceanography

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26 years as a professional scientist conducting academic quality research on mostly classified projects involving math/physics modeling and simulation, data analysis and signal processing, instrument development; often ocean related

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J. Physical Oceanography, 1984 "A Numerical Model for Low-Frequency Equatorial Dynamics", with M. Cane

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M.S. MIT Physical Oceanography, B.S. UC Berkeley Applied Math

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