26-07-2014, 10:41 AM
AUTOMATIC RAILWAY SIGNAL
AUTOMATIC RAILWAY SIGNAL.docx (Size: 713.33 KB / Downloads: 38)
INTRODUCTION
1.1 Description:
We know that the railway network of India is the biggest in south Asia and perhaps the most complicated in all over the world. There are so many different types of trains local, fast, super fast, passenger, goods etc. and their so many multiple routs. Although the time table is perfect it is not at all possible to maintain it. And that’s why the train accidents are becoming more and more usual. So why not we add a kind of intelligence to the train signals itself so that it tries to avoid accidents.
Railway signaling is a system used to control railway traffic safely, essentially to prevent trains from colliding. Being guided by fixed rails, trains are uniquely susceptible to collision; furthermore, trains cannot stop quickly, and frequently operate at speeds that do not enable them to stop within sighting distance of the driver.
What we have to do is we have to attach a transmitter with signal pole which will start transmitting signals only when the red light is on. If there is green light no transmission. The engine has a receiver which catches these transmitted signals and takes desire actions.
The transmitter and receiver are of RF type with minimum range of 2 Km. so that train can get enough time to decrease its speed and stop before the signal pole with minimum swapping distance of 100-200 meter.
Here in our project we have used one IR transmitter and five IR receivers are used for the project. The transmitter transmit the signal to the receivers when train passing from the one signal and all the receivers takes the action as per our programming.
2 Why we use signal blocks?
The earliest rail cars were first hauled by horses or mules. A mounted flagman on a horse proceeds some early train. Hand and arm signals were used to direct the “train drivers”. Foggy and poor-visibility conditions gave rise to flags and lanterns. Wayside signaling dates back as far as 1832, and used elevated flags or balls that could be seen from afar.
Block signals, as the name suggests, operate based on blocks of track. If the block of track on the opposite side of a signal is occupied, the signal is red. If not, it is green. A block of track consists of all track tiles reachable from a given piece of track without crossing over signals.
1.3 Basics:
Our project is based on automatic railway signal, in which five stations are used. There is one transmitter, and five receivers. The obstacle sensors are also connected to the transmitter which senses the obstacle position. The output of sensor is fed to the microcontroller. Controller senses passing of train through transmitter then it sends serial output command for all five receivers. It sends command for all with station identity and one which matches the code takes the action at a time.
Due to sensors, when train passing from first sensor, it senses the position of train and sends the serial output data through the transmitter to all receiver then it blink RED LED. After that when train passes from second sensor, the second sensor senses and glow RED LED and the first sensor blinks yellow LED. Same process is repeat again, and so third sensor senses the position of train and blink RED LED, second sensor blinks yellow and first sensor blinks double yellow signal. Now when train passing from fourth sensor. Then it blinks RED, third blinks yellow. Second blinks double yellow and first blinks GREEN LED. And this process is repeat again and the system working continuously
Track transmitter circuit description
One of the most common ways to determine whether a section of line is occupied is by use of a track circuit. The rails at either end of each section are electrically isolated from the next section, and an electrical current is fed to both running rails at one end. A relay at the other end is connected to both rails. When the section is unoccupied, the relay coil completes an electrical circuit, and is energized. However, when a train enters the section, it short-circuits the current in the rails, and the relay is de-energized.
This method does not explicitly need to check that the entire train has left the section. If part of the train is left in the section, that part will continue to be detected by the track circuit.
This type of circuit is used to detect the absence of trains, both for the purpose of setting the signal indication and for providing various interlocking functions. for example, not permitting points to be moved when a train is standing over them. Electrical circuits are also used to prove that points are in the appropriate position before a signal over them may be cleared. Modern trains, and staff working in track circuit block areas, carry Track Circuit Clips (TCC) so that, in the event of something fouling an adjacent running-line, the track circuit can be short-circuited. This places signals on that track to 'danger' and can be used to help prevent a collision before the signalman can be alerted.
Introduction
The AT89S52 is a low-power, high-performance CMOS 8-bit microcomputerwith 8k byte of Flash programmable and erasable read only memory. It is compatible with the industry-standard 89c51 and 89c51 instruction set and pin out Atmel AT89s52 is a powerful microcomputer which provides a highly flexible and cost-effective solution to many embedded control application.
The Atmel AT89S52 is an 8051 based Full Static CMOS controller with Three-Level Program Memory Lock, 32 I/O lines, 3 Timers/Counters, 8 Interrupts Sources, Watchdog Timer, 2 DPTRs, 8K Flash Memory, 256 Bytes On-chip RAM.
8 Obstacle sensor
• Obstacle sensor is a light sensor. When light falls on the. sensor. It conducts and when light do not fall it do not conduct. Signal from sensor is fed to microcontroller to know whether obstacle is there. Obstacle is there light do not fall and signal is low.
• A Light Sensor generates an output signal indicating the intensity of light by measuring the radiant energy that exists in a very narrow range of frequencies basically called "light", and which ranges in frequency from "Infrared" to "Visible" up to "Ultraviolet" light spectrum. The light sensor is a passive devices that convert this "light energy" whether visible or in the infrared parts of the spectrum into an electrical signal output. Light sensors are more commonly known as "Photoelectric Devices" or "Photo Sensors" becuse the convert light energy (photons) into electricity (electrons).
Conclusion
From our project we conclude that easily provide the safety of signalling system. we can control speed of the train according to automatic railway signal. By using the interfacing with PC we can easily know the location of the train.