For road and highway systems the safe and efficient flow of traffic through
intersections is paramount. Traffic is controlled at the intersection of roads by
traffic lights and traffic signals to ensure there are no accidents or collisions.
In some traffic signal control systems the period of green signals and red
signals can change depending on the time of day and traffic conditions, as can
the duration that pedestrians can cross roads in front of stationary traffic. To
meet all these requirements of a real time interconnected system, the “Solar
Powered, Computer Controlled Real –Time T-Junction Traffic Light with
Camera” is the ideal embedded platform due to its robust design, compact
design factor, reliable high performance processor and multitude of interfaces
for connection to communications equipment and redundant communications
The ruggedized compact design makes this scheme suitable to be mounted in
a roadside outdoor cabinet that is exposed to the most extreme weather
conditions. The ultra reliable processor technology provides the stability and
reliability required for real time traffic signal control and the networking
support to interconnect signals and the traffic control centre.
Ruggedized industrial design, wide operating temperature, fanless,
dustproof and suitable for installation in an outdoor roadside cabinet.
Reliable high performance processor with Windows support for
customized real time control and networking applications
Traffic lights, which may also be known as stoplights, traffic lamps, traffic
signals, stop-and-go lights, robots or semaphore, are signaling devices
positioned at road intersections, pedestrian crossings and other locations to
control competing flows of traffic. Traffic lights have been installed in most
cities around the world. They assign the right of way to road users by the use
of lights in standard colors (red - yellow - green), using a universal color
code (and a precise sequence to enable comprehension by those who are color
blind). In China, there were unsuccessful attempts to change the meaning of
"red" to "go" during the Cultural Revolution.
Typically, traffic lights consist of a set of three colored lights: red, yellow and
green. In a typical cycle,
Illumination of the green light allows traffic to proceed in the direction
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, to provide some support for people with red-green color
blindness. (And indeed, many "green" traffic lights have blue lenses with a
yellowish bulb behind them, the combination yielding a green color.)
Fig. 1.1 The control loop
Figure 1.1 illustrates the basic elements of a control loop. The traffic flow
behavior in the (road or freeway or mixed) traffic network depends on some
external quantities that are classified into two groups: Control inputs that are
directly related to corresponding control devices (actuators), such as traffic
lights, variable message signs, etc.; Disturbances, whose values cannot be
manipulated, but may possibly be measurable (e.g. demand) or detectable
(e.g. incident) or predictable over a future time horizon. The network’s output
or performance is measured via suitable indices, such as the total time spent
by all vehicles in the network over a time horizon. The task of the computer is
to enhance and to extend the information provided by suitable sensors (e.g.
inductive loop detectors) as required by the subsequent control strategy and
the human operators. The relevance and efficiency of the control strategy
largely determines the efficiency of the overall control system. Therefore
control strategies should be designed with care, via application of powerful
and systematic methods of optimization and automatic control, rather than
via questionable heuristics.
The objective of this seminar is to develop a compact unit that allows for
optimum utilization of the traffic control system by employing a customizable
traffic control system that will meet the test of time. This system will be a
powerful and flexible tool that will offer this service at any time with the
constraints of the technologies being applied.
The proposed approach for designing this system is to implement a “Solar
Powered, Computer Controlled Real –Time T-Junction Traffic Light with
Camera” control module that receives its instructions and commands from a
host computer serving as the core of the system. The computer then will carry
out the issued commands.
Mars halite traffic signal formerly fitted in various intersections in Melbourne,
Australia, indicating how much time remained before a signal change.
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. They
resembled railway signals of the time, with semaphore arms and red and
green gas lamps for night use. The gas lantern was turned with a lever at its
base so that the appropriate light faced traffic. Unfortunately, it exploded on 2
January 1869, injuringor killingthe policeman who was operating it.
Fig 2.0: An LED traffic light (Siemens Helios) in Portsmouth, United Kingdom.
The modern electric traffic light is an American invention. As early as 1912 in
Salt Lake City, Utah, policeman Lester Wire invented the first red-green
electric traffic lights. On 5 August 1914, the American Traffic Signal Company
installed a traffic signal system on the corner of East 105th Street and Euclid
Avenue in Cleveland, Ohio. It had two colors, red and green, and a buzzer,
based on the design of James Hoge, to provide a warning for color changes.
The design by James Hog allowed police and fire stations to control the signals
in case of emergency. The first four-way, three-color traffic light was created
by police officer William Potts in Detroit, Michigan in 1920. In 1922, T.E.
Hayes patented his "Combination traffic guide and traffic regulating signal"
(Patent # 1447659). Ashville, Ohio claims to be the location of the oldest
working traffic light in the United States, used at an intersection of public
roads until 1982 when it was moved to a local museum.
The first interconnected traffic signal system was installed in Salt Lake City in
1917, with six connected intersections controlled simultaneously from a
manual switch. Automatic control of interconnected traffic lights was
introduced March 1922 in Houston, Texas. The first automatic experimental
traffic lights in England were deployed in Wolverhampton in 1927. In 1923,
Garrett Morgan patented his own version. The Morgan traffic signal was a T-
shaped pole unit that featured three hand-cranked positions: Stop, in all -
directional stop position. This third position halted traffic in all directions to
allow pedestrians to cross streets more safely. It’s one "advantage" over
others of its type was the ability to operate it from a distance using a
The color of the traffic lights representing stop and go might be derived from
those used to identify port (red) and starboard (green) in maritime rules
governing right of way, where the vessel on the left must stop for the one
crossing on the right.
Fig 2.1: Computerized traffic control box Turin
Timers on traffic lights originated in Taipei, Taiwan, and brought to the US
after an engineer discovered its use. Though uncommon in most American
urban areas, timers are still used in some other Western Hemisphere
countries. Timers are useful for drivers/pedestrians to plan if there is enough
time to attempt to cross the intersection before the light turns red and
conversely, the amount of time before the light turns green.
In the traffic controllers above, the operation is purely static meaning that the
sole control is initiated and governed by the system controller. But here, in
this seminar, a different approach is adopted; the control in this regards is the
sole responsibility of the computer for ease of control and versatility.
With the introduction of a computer in the design, customizing the operation
of the control will be very easy and will also be easily adopted to suit different
METHOD OF OPERATION
Traffic Controller Hardware
The traffic controller hardware is developed using ATmega128 128Kbyte
microcontroller. The microcontroller has 32 pins I/O ports. The ports will be
used to drive 10 phases traffic light system. Since a phase has three lights,
which are green, amber and red light, and each light is driven by a relay
switch, then the I/O ports will be used to drive 30 relay units. The I/O ports
will also be used to drive 1 unit of character LCD, 30 LEDs to control the ports
status, communicate with an industrial computer through serial
communication and communicate with the Real Time Clock (RTC). In order to
perform all of the tasks, about 40 pins are required; 30 pins used to drive the
relays and the LEDs, 6 pins used to drive the character LCD, 2 pins to
communicate with the industrial computer and 2 pins to perform serial
communication. Hence, several manipulation techniques are needed to save
the use of the microcontroller’s ports.
The microcontroller as the processor needs to be programmed to work
smartly with perfect communication with the computer. The controller
system is designed to be able to optimize the traffic flow using 3 kinds of
strategies, which are green time split and time slot, green time extension, and
offset optimization strategy. In order to execute the entire strategies, except
the time slot strategy, the controller must be integrated with the industrial
computer. The time slot strategy is the backup strategy when the industrial
Basically, there are three main tasks that must be handled by the processor,
which are clock and time slot data reading, timing and incoming data
monitoring all these via the industrial computer. The first task is performed at
the beginning of every traffic cycle while the last two tasks must be handled in
real time. In order to handle the real time tasks, the internal timer
interruption of the processor needs to be activated. In the proposed traffic
controller hardware, the timer interruption will be set to 250 ms, it means the
timing and data monitoring process will be executed 4 times per second. It
will allow the tasks to be carried out thoroughly. By using this technique, the
processor will have a very high probability of capturing the serial data from
the computer successfully.
Fig 3.0: Flow chart of the system program
Actually, the controller hardware can work independently, without the need
for integration with the software. Since it optimizes the traffic flow using
traffic sensor, the interface software is needed. The software has the
interfaces for displaying and changing the time slot timing, adjusting the
internal clock of the traffic controller hardware, sending the green time data
for the next phase and extending the current green time with both + (prolong)
and – (shorten) value.
Today’s cameras all derive from the 16th-century camera obscure. The
earliest form of this device was a darkened room with a tiny hole in one wall.
Light entered the room through this hole and seminared an upside-down
image of the subject onto the opposite wall. Over the course of three centuries
the camera obscure evolved into a handheld box with a lens replacing the
pinhole and an angled mirror at the back. The mirror reflected an image onto
a ground-glass viewing screen on the top of the box. Long before film was
invented artists used this device to help them draw more accurately. They
placed thin seminar onto the viewing screen and could easily trace the
Fig 3.1 Analysis of a pin-hole
In this device, an automated camera is connected to the triggering mechanism
for the corresponding traffic light, which is targeted to monitoring the lanes.
In some countries such as United States, private companies have been
contracted to operate traffic-related cameras and in turn receive a portion of
the resulting revenues. In some cases red light cameras have been abused by
local governments, where vehicle operators have been fined as a result of
traffic systems that have been improperly modified.
This device uses a CCTV – Closed Circuit TV camera. This offers a real –time
video streaming and monitors the congestion rate in the lanes. The image
below shows a typical CCTV camera.
Fig 3.2 CCTV Camera
Computer Programs are set of instructions that direct a computer to perform
some processing function or combination of functions. For the instructions to
be carried out, a computer must execute a program, that is, the computer
reads the program, and then follows the steps encoded in the program in a
precise order until completion. Programs falls into two major classes:
application programs and operating systems. An application program is one
that carries out some function directly for a user, such as word processing or
game-playing. An operating system is a program that manages the computer
and the various resources and devices connected to it.
In this seminar, the application program that controls the whole operation of
the system is discussed and this is referred as the traffic control software.
Actually, the controller hardware can work independently, without the need
for integration with the software, but since it optimizes the traffic flow using
traffic cameras, interface software is needed. The software has the interfaces
for, storing and processing digital image from the camera, displaying and
changing the time slot timing, adjusting the internal clock of the traffic
controller hardware, and for sending the green time data for the next phase.
The software used in this system is developed with Visual Basic 6.0. This
makes the application compatible with every computer that runs on windows
Solar energy radiation is produced by nuclear fusion reactions deep in the
Sun’s core. The Sun provides almost all the heat and light Earth receives and
therefore sustains every living being.
Solar cells called photovoltaic made from thin slices of crystalline silicon,
gallium arsenide, or other semiconductor materials convert solar radiation
directly into electricity. Cells with conversion efficiencies greater than 30
percent are now available. By connecting large numbers of these cells into
modules, the cost of photovoltaic electricity has been reduced to 20 to 30
cents per kilowatt-hour. Solar power used in this device supplies constant
electric power to the computer, cameras and traffic lighting system. An image
describing the real- time implementation of solar powered traffic light is
Fig 3.3 Image, Real Time Implementation of Solar Traffic Light
PRINCIPLE OF OPERATION
The principle of operation of this traffic control device can well be explained
by the use of the block diagram shown below.
Fig3.4 Block Diagram, Solar Powered, Computer Controlled Real –
Time Traffic Light with Camera
From the diagram above it can be seen that there are four Cameras, each is
mounted on the four lanes to monitor the movement of cars and pedestrians.
The cameras are all connected to a hub like in computer network. The hub
then sends video signal to the computer which uses it to determine the action
to take based on the pre-written program (software) controlling the
The solar energy power in diagram powers the whole system while the traffic
massage display displays information such as the maximum speed limit and
road directions. It can also be used to give traffic warning such as “Bumps
Ahead” , “Sharp Bend”, “Rail Way Crossing” etc.
The traffic lights as we all know gives road users information on when to
move or stop in a junction. The traffic light convention is maintained in the
design of this work. This goes like this;
Red ---------------------- Stop
Green ---------------------- Go
Red + Amber ------------- Get ready to stop
Green + Amber ---------- Get ready to go
This seminar shows the development of the smart traffic controller system.
The use of a computer instead of other controllers is far preferred to the use
of Programmable Logic Controller (PLC). This design makes the smart traffic
controller hardware a low cost system. The proposed manipulations
techniques are to save enhance system implemented. A program downloaded
into the microcontroller enables it to establish a high accuracy timing, high
consistently in performing data interchange with the industrial computer. The
developed software also works well as the interface between the traffic
controller hardware with the traffic sensors and the traffic expert. The
software can be used to perform traffic data interchange and it enables the
proposed system to realize several traffic flow optimization strategies at a
single or network junctions.
As in many other engineering disciplines, only a small portion of the
significant methodological advancements have really been exploited in the
field as of yet.
More precisely, the majority of small and big cities even in industrialized
countries are still operating old-fashioned fixed-time signal control strategies,
often even poorly optimized or maintained. Even when modern traffic-
responsive control systems are installed in terms of hardware devices, the
employed control strategies are often naïve, poorly tested and fine-tuned, thus
failing to exploit the possibilities provided by the relatively expensive
In this regards, further improvement should be targeted at;
Wireless control should be incorporated to it for improved connectivity
CCTV should also be incorporated for surveillance purposes
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