A Seminar Report on

ANTI COLLISION DEVICES FOR TRAIN

Prepared by : Patel Jaymin V.

Roll No : 29

Semester : 8th Semester

Class : B.E. 4th (Electronics & Communication Engineering)

Year : 2010-2011

Guided by : Prof Ketki Joshi

Department of Electronics and Communication Engineering2010-11

Sarvajanik College of Engineering & TechnologyDr. R.K. Desai Road, Athwalines,

Surat-395001

Sarvajanik Education Society

Sarvajanik College of Engineering &Technology, Surat

Department ofElectronics and Communication Engineering,

CERTIFICATE

This is to certify that the Seminar report entitled “ANTI COLLISION DEVICES FOR TRAIN” is prepared & presented by Patel Jaymin V. (Roll no. 29) of B.E. IV Sem VII Electronics & communication Engineering department during year 2010-11. His work is satisfactory.

Signature of guide Head of the DepartmentElectronics & Communication

Engineering

Signature of Jury Members

Acknowledgement

I take this opportunity to express my sincere thanks and deep sense of gratitude to my guide Prof. Ketki Joshi for imparting me valuable guidance during my preparation of this seminar. She helped me by solving many of my doubts and suggesting many references.

I would also like to offer my gratitude towards faculty member of Electronics & Communication Department, Who helped me by giving valuable suggestion and Encouragement which not helped me in preparing this presentation but also in having a better insight in the field. Lastly I express deep sense of gratitude toward my colleagues who directly or indirectly helped me while preparing this seminar.

ABSTRACT

The Anti Collision Device (ACD) Network is a Train Collision prevention system

patented by Konkan Railway Corporation Limited. ACDs have knowledge embedded

intelligence. They take inputs from GPS satellite system for position updates and network

among themselves for exchanging information using their data radio modems to take

decisions for timely auto-application of brakes to prevent dangerous 'collisions', thus forming

a 'Raksha Kavach'.

ACDs fitted act as a watchdog in the dark as they constantly remain in lookout for

other train bound ACDs, within the braking distance required for their relative speeds. They

communicate through their radios and identify each other. If they happen to find themselves

on the same track and coming closer to each other, they automatically restrain and stop each

other, thereby preventing dangerous head-on and rear-end collisions.

Loco ACD of a train also applies brakes to reduce the train speed either to 15 km/h if

on approach it receives a message from other train bound ACD that has stopped in a block

section on adjacent track or to bring the train to a stop if train bound ACDs of other train are

radiating 'train parted' message thereby preventing dangerous side collision that may occur

due to infringement of adjacent track by a stopped or a 'parted' train, respectively.

1 INTRODUCTION

Anti-Collision Device (ACD) is a self-acting microprocessor-based data

communication device designed and developed by Kankan Railway. When installed on

locomotives (along with an auto-braking unit - ABU), guard vans, stations and level-crossing

gates (both manned and unmanned), the network of ACD systems prevents high-speed

collisions in mid-sections, station areas and at level-crossing gates.

The ACD uses both radio frequency and Global Positioning System (GPS) through satellites,

whereby a train is automatically brought to a halt if the track ahead is not clear. The train

starts braking 3 kms ahead of a blockade.

The Anti-Collision Device, also called `Raksha Kavach,' envisages setting up a

network of "self-acting" micro-processor based communication devices which automatically

apply brakes on trains that are unknowingly getting into a "collision-like situation," including

before stations and at mid-sections. At the mid-sections, where neither the protection of

signals nor guidance is available to the driver, the ACD makes the loco intelligent and

extends its capability to detect any collision-like situations in a range of 3 km, which the

driver cannot detect on his own. Situations like collision between two approaching trains or

between a derailed train on one track and an approaching train on the adjacent tract can thus

be prevented.

ACD senses an obstacle in path of the train or any another is coming on the same

track from another side. Here, dealing with the condition of collision between two trains and

try to find out the method to avoid the collision in normal and abnormal condition. So

implementation of a device which can avoid the collision between two trains mean an ANTI

COLLISION DEVICE (ACD)

ACDs work on the principle of ‘Distributed Control Systems’. ACDs interact en-

route with each other through radio communication within a radial range of 3 Kms. If 2

ACDs are at a risk of collision, the ACD system activates automatic braking. Intelligent

braking system to ensure optimum braking and minimizes loss of operational time. Whenever

a collision is sensed, the loco ACD applies the brakes automatically.

2 HISTORY

In early days the mode of transportation is very slow as the time passes world made

progress and the different revolution takes place which demands the fast mode of

transportation. The new generation of fast transportation are the railways, aero planes, cars

etc. The railway transportation is very important for any nation. Railways is very fast service

and hence there is a possibility of accidents like collisions, derailment and accident due to

weather condition

3.Different types of the accidents

3.1 Rear-end Collision

A rear-end collision is a traffic accident wherein a vehicle (usually an automobile or a

truck) crashes into the vehicle in front of it, so called because it hits its rear. It may also be a

rail accident wherein a train runs into the rear of a preceding train. Typical scenarios for rear-

ends are a sudden deceleration by the first car the following car that does not have the time to

brake and collides with the first at a road junction the following car accelerates more rapidly

than the leading.

3.2 Head on Collision

A head-on collision is one where the front ends of two ships, trains, planes or vehicles

hit each other, as opposed to a side-collision or rear-end collision.”With rail, a head-on

collision often implies a collision on a single line railway. This usually means that at least

one of the trains has passed a signal at danger, or that a signalman has made a major error.

Head-on collisions may also occur at junctions, for similar reasons.

4. NEED OF A.C.D.

The main modules of the ACD includes a GPS (Global Positioning System), which

picks up signals from the constellation of GPS satellites that are being exclusively used for

this purpose. The GPS submits the data to the Command and Control Unit (CCU) to extract

the parameters related to the movement of locomotive like latitude, longitude, speed, angle,

date and time. The antenna of the GPS receiver is fitted outside on the roof of the locomotive.

The user-friendly device helps the driver to know the various positions in the form of

audio-visual indications, like Station Approach, SOS (for head-on, rear-end and side collision

situations) and Gate Open. Another module is the radio trans-receiver, which transmits the

information and commands generated by the CCU and receives the information being sent by

other ACDs when the two systems are within the radio-range of 3 km.

The final module in the system is the braking mechanism, which envisages the CCU

to take a decision for applying either the normal brake or the emergency brake on the

locomotive as the situation required. "The electro-pneumatic braking is then applied through

suitable solenoid interface installed for this purpose in the cab of the locomotive," the official

explained.

ACD is an intelligent friend to the engine driver, which can act on its own without

any human intervention. It comprises a Command and Control Unit (CCU), a GPS Receiver,

Radio Transmitter and Crew Interface. The CCU, which is the heart of the ACD, is a

microprocessor-based module which processes the data and generates commands. The GPS

Receiver picks up signals from GPS satellites and submits the same to the CCU to extract

parameters related to the movement of the locomotive such as latitude, longitude, speed,

angle, date and time.

ACD prevents the head-on collision of two speeding trains, which accidentally

happen to be on the same track. An ACD mounted on a train constantly looks out for signals

from another ACD in a 3-km range. The moment both the trains are within the required

breaking distance, the ACDs, after analysing the data from the GPS, deduce that they are on

the same track and are heading for a collision. Then the ACDs automatically apply the

brakes, bringing both the trains to a halt without the intervention of the driver.

The ACD can be used not only for avoiding head-on collisions but also to detect if a

train has accidentally stopped on the same track as another, preventing a following train

telescoping into its rear. Also, if two trains are moving on the same track but the separation

distance is less than 2 km, the ACD will automatically regulate the following train's speed. It

can also detect when the bogies of a train from an adjacent track derail on to a train's path.

Konkan Railways has tested out 11 accident scenarios with the ACD.

The ACD can be mounted not only on trains but also be installed at railway stations,

level crossing gates (both manned and unmanned), and on guard vans. If a station is equipped

with an ACD, the driver will receive the ``station approach'' warning as the train approaches

the station. Also, the ACD can sense whether a level crossing gate is open or damaged and

warn the driver, besides regulating the train's speed.

5. Features of ACD

The principal object of the present invention is to overcome these disadvantages and provide

an anti-collision safety device for vehicles travelling on tracks, without any driving personnel, that is

to say, a device which itself can estimate risks and react in consequence

1. Detection & Prevention of Head-on, Rear-end and Side Collisions – A unique feature

even when a train is not protected by a signal, as in a block section.

2. Detection & generation of Train Parting / Jumbling-Consequently bringing any

approaching train on the adjoining line to a dead stop.

3.‘Train Approach’ Warning for road users at Level Crossings both manned and

unmanned - In addition, at manned non-interlocked level crossings, reducing the train

speed to 30 Kmph in case the gate is detected in ‘open’ condition through gate ACD.

4 . Speed limit imposition - Based on ‘preset’ conditions in functional requirements

Specification (FRS) of ACD.

5. Manual SOS functionality available for Drivers, Guards and Station Masters –

6. To bring all trains to a halt within a radial distance of 3 Kms, in emergencies.

7. Auto Brake Test – Generating braking characteristics for a Train ‘without manual

feeding’ of data of coaches / load.

8. A unique feature as train characteristics are required to be fed ‘manually’ in all other

systems in the world.

6.Technology used in ACDs:-

The basic idea of the Railway Collision Avoidance System (RCAS) is similar to broadcast information about position, movement vector and others form the moving units as well as from specific infrastructure elements. Basically the trains and rail vehicles determine their position and movement vector and broadcast this information to all other trains in the area which is only limited by the range of the RCAS-sender. Each moving unit on the rails like regular trains, work trains, road rail vehicles, etc. can be equipped with RCAS. The RCAS-units receive all broadcasted information and compare position and movement vector with the own one to detect possible collisions. Fig. shows the basic interaction of the RCAS components.

Figure Interaction of the components of RCAS

The main challenge of RCAS is the evaluation of the trajectories of the vehicles. It is quite

normal that the movement vectors of trains are direct in opposite (e.g. coupling) respectively

almost in opposite (e.g. passing trains on parallel tracks).

7. COMPONENTS

The main components of ACD are as follow-

1. Command Control Unit(CCU)

2. Automatic Braking Unit(ABU)

3. GPS

7.1 Command Control Unit(CCU)

The Command Control Unit is the brain of the ACD system. It take the important decision

regarding the movement of train when another train is in the same track.The CCU take decision

according to the particular situation and if the situation is not under control than applied the brakes

automatically .The CCU mainly of the two components.

1. Microprocessor

2. Radio Tran receivers

Microprocessor

Intel 80386, otherwise known as the Intel386, i386 or just 386, is a microprocessor

which has been used as the central processing unit (CPU) of many personal computers and

workstations since 1986. As the original implementation of the 32-bit form of the 8086-

architecture, the i386 instruction set, programming model, and binary encodings is still the

common denominator for all 32-bit x86 processors. Successively newer implementations of

this same architecture have become several hundred times faster than the original i386 chip

during these years (or thousands of times faster than the 8086). A 33 MHz i386 was

reportedly measured to operate at about 11.4 MIPS. The 80386 featured three operating

modes: real mode, protected mode and virtual mode. The protected mode which debuted in

the 286 was extended to allow the 386 to address up to 4 GB of memory. The all new virtual

8086 mode (or VM86) made it possible to run one or more real mode programs in a protected

environment.

VxWorks is designed for use in embedded systems. Unlike "native" systems such as

Unix, VxWorks development is done on a "host" machine running Unix or Windows, cross-

compiling target software to run on various "target" CPU architectures.

The Foundation: VxWorks 6.x -The VxWorks platforms are based on the world’s

most widely adopted RTOS. Built on a highly scalable, deterministic, hard real-time kernel,

VxWorks enables companies to scale and optimize their run-time environment using only the

specific technologies required by their device. From the smallest footprint requirement to the

highest performance level, VxWorks gives developers the flexibility to build their optimal

solution quickly and easily hile meeting cost, quality, and functionality requirements.

VxWorks supports POSIX and industry-standard protocols such as IPv6 and TIPC, ensuring

maximum code portability and interoperability. VxWorks 6.x is backward-compatible with

previous releases, so developers can leverage and reuse existing projects, applications, board

support packages (BSPs), and drivers, as well as open source applications. VxWorks 6

includes frameworks for file systems, power management, and interconnectivity, as well as

comprehensive security capacities that begin at the core operating system level for absolute

application and device security.

7.2 Radio Trans receiver

The s enso r consists of an i nduc t i on l oop . E l ec t r i c cu r r en t generates a

magne t i c f i e l d , which collapses generating a current that falls asymptotically toward zero

from its initial level when the input electricity ceases. The i nduc t ance of the loop changes

according to the material inside it and since metals are much more effective inductors than

other materials the presence of metal increases the current flowing through the loop.

This change can be detected by sensing circuitry, which can signal to some other

device whenever metal is detected. Common applications of inductive sensors include me t a l

de t ec to r s , t r a f f i c l i gh t s , c a r washes , and a host of automated industrial processes.

Because the sensor does not require physical contact it is particularly useful for applications

where access presents challenges or where dirt is prevalent. The sensing range is rarely

greater than 2 cm, however, and it has no directionality.

A Proximity sensor can detect objects without physical contact. A proximity sensor

often emits an electromagnetic field or beam and look for changes in the field. The object

being sensed is often referred to as the proximity sensor's target. Different proximity sensor

targets demand different sensors. For example, a capacitive or photoelectric sensor might be

suitable for a plastic target; an inductive proximity sensor requires a metal target.

In capacitive proximity sensors, the sensed object changes the dielectric constant between two

plates. A proximity sensor has a range, which is usually quoted relative to water. Because changes in

capacitance take a relatively long time to detect, the upper switching range of a proximity sensor is

about 50 Hz. The proximity sensor is often found in bulk-handling machines, level detectors, and

package detection. One advantage of capacitive proximity sensors is that they are unaffected by dust

or opaque containers, allowing them to replace optical devices. Conditioning the output of a proximity

sensor has always been difficult. Proximity sensor designers must confront linearity, hysteresis,

excitation voltage instability, and voltage offset. A proximity sensor that measures current flow

between the sensing electrode and the target provides readouts in appropriate engineering units.

7.3 Automatic Braking Unit(ABU)

Automatic Braking Unit is used to slow down the speed of train coming on the same track.

This braking unit has linked with braking mechanism of the locomotive to control the speed of the

train. This braking unit reduces the speed of the train from 50km/hr to 20km/hr and hence it deduces

the braking characteristic of the train. An ACD fitted train would now apply the brakes on the braking

characteristic of the train whenever the situation of the collision is perceived.

The air delivered by the compressor flows through the coupled main air reservoir pipe to the

man air reservoirs in the different cars, where a pressure of 6-7 kg/cm 2 (85-100psi) builds up. At the

same time, the air flows through the centrifugal filters to the brake controllers.

Loco ACD Interfacing Diagram

The whole train is controlled from one driver's compartment. In this manned driver's

compartment, the hand-operated isolating valve on the brake controller must be opened with the

detachable handle. This establishes the electrical connections required for operation of the electrically

controlled airbrake. In the unmanned driver's compartments the hand-operated isolating valve on the

brake controller must be closed. Only one handle for turning the isolating valve should be available in

each train. Since this handle is required for the brake controller which is in operation and it can only

be removed when the isolating valve is closed, it follows that the isolating valves in the unmanned

driver's compartments must be closed. The driver's handle of the brake controller in the unmanned

driver's compartments must be in running position.

7.4 GPS(Global positioning System)

A GPS receiver calculates its position by carefully timing the signals sent by the GPS satellites high above the Earth. Each satellite continually transmits messages containing the time the message was sent, precise orbital information (the ephemeris), and the general system health and rough orbits of all GPS satellites (the almanac).

The receiver measures the transit time of each message and computes the distance to each satellite. Geometric trilateration is used to combine these distances with the location of the satellites to determine the receiver's location.

Figure ACD-GPS communication

The position is displayed, perhaps with a moving map display or latitude and longitude; elevation information may be included. Many GPS units also show derived information such as direction and speed, calculated from position changes.It might seem three satellites are enough to solve for position, since space has three dimensions. However a very small clock error times the very large speed of light—the speed at which satellite signals propagate—results in a large positional error. The receiver uses a fourth satellite to solve for x, y, z, and t which is used to correct the receiver's clock. While most GPS applications use the computed location only and effectively hide the very accurately computed time, it is used in a few specialized GPS applications such as time transfer and traffic signal timing. Although four satellites are required for normal operation, fewer apply in special cases. If one variable is already known (for example, a ship or plane may have known elevation), a receiver can determine its position using only three satellites. Some GPS receivers may use additional clues or assumptions (such as reusing the last known altitude, dead reckoning, inertial navigation, or including information from the vehicle computer) to give a degraded position when fewer than four satellites are visible.

8. The working of Anti Collision Devices

The loco ACD is the heart of ACD network. In the ACD the radio signal from the consolation

of Global Positioning System (G.P.S) satellite or received by GPS receiver through by antenna. This

signal is sent to the command and control unit that is C.C.U. of the ACD the C.C.U is micro

processor based module and act as a brain of the ACD system.

ACD Network

The GPS submits the data to the Command and Control Unit (CCU) to extract the

parameters related to the movement of locomotive like

Latitude.

Longitude.

Speed.

Angle.

Date and time.

It processed the data and generated the commend from the ACD. A part from the GPS

receiver there is a radio Trans receiver inside the ACD. A transmits information such as:

Identification no.

Speed

Location in terms of Latitude, Longitude, and status of it working with the help of sprats

radio antenna.

It also receives the information being send by other ACD range within range 3 Km. This

information also send to the C.C.U. for processing all receiving the information from the

other ACD and the data from the GPS receiver. The C.C.U unit take a design for apply

either a normal & emergency break or the locomotive break as the case may be.

This is active with the help of the auto breaking unit of the loco on board mobile loco

ACD and guard room ACD have both a GPS receiver and radio trans receiver. The GPS

receiver received the data from the satellite and radio trans receiver communicate with the

other GPS. Within range of 3.Km. the tracks side and sates nary module. Such as :- station

ACD, level crossing ACD, and loco side ACD.

Both mobile and stationary ACD exchange information and take decision base on trans

working rule. And embedded software to a apply breaks automatic with art any input users.

All the ACD work on the principle of distributed control system. It’s very simply but it two

ACD on locomotive within pre define distance and proceed and risks on collision system.

Automatically active the breaking to the train and prevent collision relay in accident.

8.1 Collision detection

The basic concept is the collision detection of two trains: both trains determine their position

and movement vector. This information is transmitted together with some other information

like type of mission and train number by mobile radio to the trains in the area around.

Figure Collision detection

Each receiver compares his own position and vector with all received vectors. As soon as a

collision in the four-dimensional space (time and three space dimensions) has been identified

a specific reaction is triggered. Depending of the parameters like remaining distance, time to

collision and the speed the reaction is selected beginning from different types of warning up

to an automatic braking.

9. Accidents are prevented by ACD

Detection and Prevention of Head-on, Rear-end and Side Collisions: – Only system in

the world to provide these UNIQUE features even when a train is not protected by a signal, as

in a block section.

Detection of fouling and prevention of collision due to fouling:- Except when a Train

on main line overshoots the ‘Fouling Mark’

Detection & generation of Train parting / Jumbling: - Consequently bringing any

approaching train on the adjoining line to a dead stop.

Station Approach Warning to Drivers: - Can result in saving of Manpower for

deployment of detonators during foggy weather, Provided 100% coverage of ACD fitted

trains is available on the

Concerned ACD route.

Speed limit imposition:- Based on ‘preset’ conditions in FRS of ACD

‘Train Approach’ Warning for road users at Level Crossings both manned and

unmanned :- In addition, at manned non-interlocked level crossings, reducing the train

speed to 30 Kmph in case the gate is detected in ‘open’ condition through Gate ACD.

Manual SOS functionality available for Drivers, Guards and Station Masters: - To

bring all trains to a halt within a radial distance of 3 Kms, in emergencies

9.1 ACD network can’t prevent a train collision

Other train is a ‘NON’ ACD Train – ACD functions by reacting to another ACD, as

such if one of the two trains is a non-ACD train, the protection against collision will be

missing.

‘Adequate’ braking distance at that speed is not available when a ‘dangerous’

collision-like situation arises suddenly – However, severity of the collision would be

reduced as a function of the reaction time.

Train derails and its wagons/coaches dash with another Train, already on ‘adjacent’

track – No reaction time situation

‘Failure’ of brake power of the Locomotive/train

Rolling backward/forward of a ‘Stabled load’

Benefits of the ACD system

Very economical and cost effective.

Easily adaptable and expandable.

Does not degrade the existing safety level.

Employs state-of-art hardware and software technology.

No way had side equipment required, hence no requirement of Power.

No cabling on the track required (which is more expensive and cumbersome).

Less susceptible to Vandalism.

It does not require any inputs to be fed by the crew at the start of journey, thus human

error is eliminated.

10.APPLICATIONS

1. ACDs can be implemented in railways to prevent collisions and to decrease the timing

between two consecutive trains running one after another.

2. It can be used in heavy vehicles like cranes, earthmovers etc to prevent accidents and for

their safe working in public places.

3. ACDs can be used as a tracking device.

CONCLUSION

System to avoid collisions called railway Collision Avoidance System. This system is located completely on board of the rail vehicles and uses basically the information about position, speed and direction determined by a global navigation satellite system (GNSS) and a regional broadcast of this and further information with mobile radio.

REFERENCES

[1] Thomas Strang and Michael Meyer zu Hörste , “A railway collision avoidance system exploiting ad-hoc inter-vehicle communications and galileo”, German Aerospace Center Institute of Communications and Navigation Institute of Transportation Systems