Traffic signal projects

7/31/2019 Traffic signal projects

1/14

7/5/12

WELCOME


2/14

7/5/12

CONTENTSTraffic lights

History

Technology

Fixed time controlDynamic control

Solar traffic lightsFeaturesAdvantage

How to repair a traffic signalInstructions

TRAFFIC

LIGHTS


3/14

7/5/12

Traffic light

Traffic lights, which may also be known asstoplights,traffic lamps,trafficsignals,stop-and-go lights,robotsorsemaphore,are signaling devices positioned atroad intersections,pedestrian crossingsand other locations to control competing flows oftraffic.

Typicallytrafficlightsconsistofasetofthreecoloredlights:red,amber/yellowandgreen.Inatypicalcycle,Illuminationofthegreenlightallowstraffictoproceedinthedirectiondenoted,Illuminationoftheamber/yellowlightdenoting,ifsafetodoso,preparetostopshortoftheintersection,andIlluminationoftheredsignalprohibitsanytrafficfromproceeding.

An LED traffic light (Siemens Helios) in Portsmouth,United Kingdom.


4/14

7/5/12

History

On December 10, 1868, the first traffic lights were installed outside the Parliament in London,by the railway engineerJ. P. Knight. They resembledrailway signalsof the time, with

semaphore arms and red and green gas lamps for night use. The gas lantern was turned with alever at its base so that the appropriate light faced traffic. Unfortunately, it exploded on 2 January1869, injuringor killing the policeman who was operating it.

Mars halitetraffic signal. Formerly fitted in various intersections in Melbourne, Australia, indicating how much time remained before a signal change.


5/14

7/5/12

Technology

Optics and lighting

Traditionally, halogen bulbs were used. Because of the low efficiency of light output anda single point of failure (filament burnout) municipalities are increasingly retrofitting traffic

signals withLED arrays that consume less power, have increased light output, lastsignificantly longer, and in the event of an individual LED failure, still operate albeit witha reduced light output. With the use of optics, the light pattern of an LED array can becomparable with the pattern of an incandescent or halogen bulb.

An example of an LED trafficlightAustralia


6/14

7/5/12

Fixed time control

The simplest control system uses a timer (fixed-time): each phase of the signal lasts for a specificduration before the next phase occurs; this pattern repeats itself regardless of traffic. Many oldertraffic light installations still use these, and timer-based signals are effective inone waygridswhere it is often possible to coordinate the traffic lights to the posted speed limit. They are

however disadvantageous when thesignal timingof an intersection would benefit from beingadapted to the dominant flows changing over the time of the day.

Dynamic control

Dynamic, or actuated, signals are programmed to adjust their timing and phasing to meet changingtraffic conditions. The system adjusts signal phasing and timing to minimize the delay of peoplegoing through the intersection. It is also commonplace to alter the control strategy of a traffic lightbased on the time of day and day of the week, or for other special circumstances such as a majorevent causing unusual demand at an intersection.The controller uses input fromdetectors, which are sensors that inform the controller processor

whether vehicles or other road users are present, to adjust signal timing and phasing within thelimits set by the controllers programming. It can give more time to an intersection approach that isexperiencing heavy traffic, or shorten or even skip a phase that has little or no traffic waiting for agreen light. Detectors can be grouped into three classes: in-pavement detectors, non-intrusivedetectors, and detection for non-motorized road users.


7/14

7/5/12

Solar traffic light

Solar traffic lightsare signaling devices powered bysolar panelspositioned at road intersections,pedestrian crossingsand other locations to control the flows of traffic. They assign theright ofwayto road users by the use of lights in standard colors (red - amber/yellow - green), using a universalcolor code(and a precise sequence to enable comprehension by those who arecolor blind.Most of the solar traffic lights havebatteryback-up for functioning during night.

Solar Energy Powered Traffic Light


8/14

7/5/12

Features

Solartraffic lightsuseLED lampsas they are more efficient, turn on instantly, last much longer,are more energy efficient and as their lifetime isn't affected by frequent cycling on and off.In

addition to having a box which encloses control circuitry, they have a separate box whichhousesbatteries. These batteries functions as a back-up by storing electrical energy from thesolar panels which is used during the night for its operation.Some models using conventionalenergy sources may usesolar energyfrom the panels as an auxiliary power source and in othercases; entire solar traffic lights may be used as an auxiliary device to be used in the event ofprimary traffic light failure.These systems feature alphanumeric displaysalong with countdowntimers that display the amount of time left before the signal changes.

Solar Energy Powered School Traffic Light Solar Panel Battery Enclosure on Traffic Light


9/14

7/5/12

Advantages

Solar traffic lights are cheaper to operate than conventionaltraffic lights, as they use solar power for their operation.

They are easier to set up and operate


10/14

7/5/12

How to Repair Traffic Signals

Traffic signals over time can stop working and be damaged due to collisions with trucks, wiresmalfunctioning and parts wearing out. Mechanical technicians who are city employees repair trafficsignals that are still in use. Citizens can purchase, repair and restore damaged or malfunctioningcity traffic signals that are no longer used. Once traffic signals are repaired, they are often sold ascollector's items or decorations for a home or property. Although some traffic signals are morecomplex than others, the general steps for restoring traffic signals are the same.

Repair Traffic Signals


11/14

7/5/12

Instructions

Disassemble the entire traffic signal and break down all of the individual parts. It will easier tomake a list of what is broken and needs replacing once the parts are laid out. The necessaryreplacement parts usually can be found and ordered online.

Submerge the traffic signal's body, as well as the light visors, in paint stripper. The paintstripper will cause the old paint to bubble and loosen, the KBR Horse website explains. Once theparts are taken out of the paint stripper, a wire brush can be used to remove the old paint.

Apply layers of spray paint to the traffic signal's body as well as the light visors. Traffic signalresearch should be conducted online in order to verify the authentic colors, the George Franciswebsite explains. The traffic signal's body is usually yellow, but the visors can be yellow or black

Clean all the traffic signal's part before rebuilding it. It is recommended that new light bulbs andwiring be installed in order to ensure that the traffic signal will work correctly.

Rebuild the traffic signal by first inserting the light bulbs and completing the wiring. Insert thelenses and screw the front of the traffic signal shut. Finally, install the traffic signal visors in orderto complete the restoration project.


12/14

7/5/12

Tips & Warnings

Paint stripper can be harmful if it comes in contact with the skin and isabsorbed.

Gloves, long sleeves, and protective glasses should be worn at all times inorder to prevent injury and serious burns.


13/14

7/5/12

Reference

www.google.com

www.winkipedia.com

ESSAR ENGINEERS
http://www.google.com/http://www.winkipedia.com/http://www.winkipedia.com/http://www.google.com/


14/14

7/5/12

THANK

YOU

Traffic signal projects

Documents

Transcript of Traffic signal projects