traffic light

1. Submitted by:-
Roshan Wanaskar:- 052
Sachin Chhimpa
053
Sachin Varshney:- 054

2. Our System:
A Traffic Light

3. • Traffic lights are signaling devices positioned at
road intersections, pedestrian crossings are today
used in almost every city of the world.
• On December 10, 1868, the first traffic lights were
installed outside the British houses of
parliament in London, by the railway engineer J.P.
Knight.
• The modern electric traffic light is an
American invention, policeman Lester
Wire invented the first red-green electric traffic
lights.
• The first four-way, three-color traffic light was
created by police officer William Potts in Detroit.

4. Traffic lights alternate the right of way accorded to road users by displaying lights
of a standard color (red, yellow/amber, and green) following a universal color
code.
In the typical sequence of color phases:
• Illumination of the green light allows traffic to
proceed in the direction denoted,
• Illumination of the yellow light denoting, if safe
to do so, prepare to stop short of the intersection,
and
• Illumination of the red signal prohibits any traffic
from proceeding.
• Usually, the red light contains some orange in its
hue, and the green light contains some blue, for
the benefit of people with red-green color
blindness.

7. The closed-loop system consists of six
components:
• System detectors
• Local control equipment
• Controller-master communications
• On-street master
• Master-central communications
and
• Central computer.

8. WHERE TO USE TRAFFIC SIGNAL?

10. Traffic Light
• Intersection of two one-way roads
A
B
Car
Sensors

11. Light A
Light B

12. Light A Possible States
Light B

13. Possible States
Light A
Light B

14. Possible States
Light A
Light B

15. Light A Possible States
Light B

16. Actually Only 4 Possibilities
Light A
Light B

17. Traffic Light Design
• We figured out some possible States of the
Traffic Light.
• Next, we should think logically about how
the Traffic Light should behave.
• For now, we will try to keep it simple.
• (Suppose these are infrequently used
country roads.)

18. How should the Light behave?
A
Light A
B
Light B Car
Sensors

19. Traffic Light Behavior
IF A=1
AND B=0
Light A
Light B

20. Traffic Light Behavior
Note:
Clock beats
every 4 sec.
IF A=1 So Light is
Yellow for
AND B=0 4 sec.
Light A
Light B

21. Traffic Light Behavior
IF A=1
AND B=0
Light A
Always
Light B

22. Traffic Light Behavior
IF A=1
AND B=0
Light A
Always
IF A=0
AND B=1
Light B

23. Traffic Light Behavior
IF A=1
AND B=0
Light A
Always Always
IF A=0
AND B=1
Light B

24. NATIONAL TRAFFIC SIGNAL
GRAB:

25. • FHWA Arterial Management Website, latest information
on traffic signal operations
• Micro Controller based Traffic Light Controller
•United States Patent and Trademark Office.
http://patft.uspto.gov/netacgi/nph-
Parser?patentnumber=6326903. Retrieved 7 October
2005.