The document describes the history and development of traffic lights, beginning with the first traffic lights installed in London in 1868, the invention of the electric traffic light by Lester Wire in America, and William Potts' creation of the first four-way three-color traffic light in Detroit. It explains the typical light sequence of red, yellow, and green and components of a closed-loop traffic light system. Finally, it provides examples of logic for how two intersecting one-way roads could operate with a basic two-light traffic control system based on sensor detection of vehicles.

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.