Application of Process Control in Traffic

Signals

Submitted by:-Roshan Wanaskar:-052Sachin Chhimpa:- 053Sachin Varshney:- 054Saket Shakti:- 056

Our System:A Traffic Light

HISTORY:-

• 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.

INTRODUCTION:

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.

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.

General Traffic Volumes:- When traffic volumes at most of the intersection approaches reach the point where other forms of control cannot efficiently assign right of way to the approaching motorists.Interruption of Continuous Traffic - When traffic on a major street is so heavy that traffic on a lightly travelled side street has little opportunity to cross or enter the main-street traffic. This condition requires heavier traffic on the main street than the previous condition, but allows lighter traffic on the side street.Pedestrian Volumes - When pedestrian traffic is heavy enough to justify the interruption of vehiculartraffic.School Crossings - If judged necessary by the traffic engineer, a traffic signal may be used to facilitate the crossing of school children.Progressive Movement - Sometimes a traffic signal will help keep platoons of cars tightly formed to enhance the coordinated flow along a street and encourage an appropriate speed.Accidents - Traffic signals are sometimes effective in reducing accidents that result from the inability of motorists to safely assign their own right of way. These accidents typically involve right-angle collisions.

WHERE TO USE TRAFFIC SIGNAL?

Traffic Light

• Intersection of two one-way roads

CarSensors

B

A

Light

A

Light B

Light

A

Light B

Possible States

Light

A

Light B

Possible States

Light

A

Light B

Possible States

Light

A

Light B

Possible States

Light

A

Light B

Actually Only 4 Possibilities

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.)

Lig

ht

A

Light B

How should the Light behave?

CarSensors

B

A

Light

A

Light B

Traffic Light Behavior

IF A=1

AND B=0

Light

ATraffic Light Behavior

IF A=1

AND B=0

Light B

Note:Clock beatsevery 4 sec.So Light is Yellow for

4 sec.

Light

ATraffic Light Behavior

IF A=1

AND B=0

Always

Light B

Light

ATraffic Light Behavior

IF A=1

AND B=0

Always

IF A=0

AND B=1

Light B

Light

ATraffic Light Behavior

IF A=1

AND B=0

Always

IF A=0

AND B=1

Light B

Always

NATIONAL TRAFFIC SIGNAL GRAB:

REFERENCES

• 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.