You are here:

Physics/Traffic Lights.

Question
Dear Prof Steve

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

What about friends like my former lab/office mate Eric, who's red-green colorblind?

I'm not an engineer, this is not a physics question about actual physics, and yes shapes can be used to replace position.  I'm not going to write an essay on something so simple that you could think it through for yourself, you'll find it much more satisfying.  I'm not sure why you're so focused on a 7-segment LED...

Physics

Volunteer

Dr. Stephen O. Nelson

Expertise

I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

Experience

I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Education/Credentials
Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.