training report on telecommunication and signal-indian railways

7/23/2019 Training Report on Telecommunication and Signal-Indian Railways

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Abstract

This report takes a pedagogical approach in demonstration of communication system and

signal transmission throughout the machinery of railways. An effort to a significant

insight into the working of the devices of railways from view point of communication has

been made. The focus of this detailed study is divided into two aspects:

Telecommunication and Signaling. Besides, various communication systems are currently

being employed in the Indian railways. actors like safety and reliability concerns are

discussed further. The design and architecture of various information systems are also

furnished. The detailed analysis is directed towards control logic for the railway

interlocking, type of communication protocols upon which the control systems depends.

Telecommunication part has been also discussed to make the report more comprehensive.A newer improvement towards !entrali"ed Traffic !ontrol has also been highlighted for

the railway system to prove itself a reliable option for its travelers.

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Acknowledgement

#e take this opportunity to e$press our profound gratitude and deep regards to our guide

%a&esh Sharan Sir for his e$emplary guidance, monitoring and constant encouragement

throughout the course of this training. The blessing, help and guidance given by him time

to time shall carry us a long way in the &ourney of life on which we are about to embark.

#e also take this opportunity to e$press a deep sense of gratitude to 'ramod Sir, for his

cordial support, valuable information and guidance, which helped us in completing this

task through various stages.

#e are obliged to (.). Singh Sir *%%I, 'atna +n., -ukesh Sir, %a&kumar Sir, 'ramod Sirand also thankful to the staff members of 'atna +unction, a&ipur +unction, Sonpur and

/anapur /ivision for the valuable information provided by them in their respective fields.

#e are grateful for their cooperation during the period of our training.

0astly, we thank Almighty, our parents and our accompanying friends for their constant

encouragement without whom this training would not have been possible.

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Table of Contents

1Introduction...........................................................................................5

2Telecommunications..............................................................................61.2 3ptical iber !ommunications...................................................................................4

1.1 5uad !able................................................................................................................. 6

1.7 'A Systems................................................................................................................28

1.9 Telephone $change..................................................................................................281.; -obile !ommunications............................................................................................21

1.4 3IS...........................................................................................................................2>>>>>>>>>>>>>>>>>>>>>>>>>>>>....12

1.6 '%S>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>.17

1.28 !ontrol System>>>>>>>>>>>>>>>>>>>>>>>>>>.19

3Signaling..............................................................................................257.2 Basic Signaling>>>>>>>>>>>>>>>>>>>>>>>>>>....1;7.1 Interlocking>>>>>>>>>>>>>>>>>>>>>>>>>>>>..14

7.7 'I and %%I>>>>>>>>>>>>>>>>>>>>>>>>>>>>>1>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>...167.; !entrali"ed Traffic !ontrol>>>>>>>>>>>>>>>>>>>>>>...71

Summary................................................................................................33References..34

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1 Introduction

Indian %ailways is one of the largest %ailways in the world. Introduced in 2


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2 Telecommunications

Telecommunication in the modern era is the science and practice

of transmitting information by electromagnetic means.

In earlier times, telecommunications involved the use of visual signals, such

asbeacons, smoke signals,semaphore telegraphs, signal flags, and optical heliographs, oraudio messages such as coded drumbeats, lung@blown horns, and loud whistles. In modern

times, telecommunications involves the use of electrical devices such as

the telegraph,telephone, andteleprinter, as well as the use of radio, microwave

transmission towers, fiber optics, orbiting satellitesand the Internet, which is a vast

world@wide computer network.

A revolution in wireless telecommunicationsbegan in the first decade of the 2688s with

pioneering developments inradiocommunicationsbyikola Teslaand uglielmo

-arconi.

2.1 Optical Fiber Communications

iber@optic communication is a method of transmitting information from one place to

another by sending pulses oflightthrough an optical fiber. The optical fiber acts as a low

loss, wide bandwidth transmission channel. A light source is re?uired to emit light signals,

which are modulated by the signal data. To enhance the performance of the

system, a spectrally pure light source is re?uired.

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CONSTRUCTION OF OPTICAL FIBR

In the late 26=8s and early 26


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normous Ban"#i"t$or glass fibers, there are two Eoptical windowsE where the fiber is most transparent and

efficient.The centers of these windows are 2788 nm and 2;;8 nm, providing

appro$imately 2


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3ptical fiberis used by many telecommunications companies to transmit telephone

signals, Internet communication, and cable television signals. /ue to much

lowerattenuationand interference, optical fiber has large advantages over e$isting copper

wire in long@distance and high@demand applications. owever, infrastructure development

within cities was relatively difficult and time@consuming, and fiber@optic systems were

comple$ and e$pensive to install and operate. /ue to these difficulties, fiber@opticcommunication systems have primarily been installed in long@distance applications, where

they can be used to their full transmission capacity, offsetting the increased cost.

2.2 'ua" Cable

Con"uctor : ach conductor consists of round wire of annealed highconductivity

copper.

Insulation ( ach conductor is insulated with solid mediumD high density

polyethylene insulation.

'ua""in%( our insulated conductors stranded to form a star ?uad, two conductors

diagonally opposite forming one pair and the remaining two diagonally opposite

conductors forming the second pairs of the ?uad.

La)in% Up( The ?uads are assembled to form a symmetrical core with a right hand

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Fig 4: Inner sections of a quad cable
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lay. 'olyethylene strungs of re?uired diameter may be used as fillers, if necessary, forproper circular core formation.

Fillin% an" core #rappin%( The cable core is fully filled with water resistant

comound which is compatible with the polythene insulation of the conductors. The

filled cable core is wrapped with at least one helical or longitudinally polythenetape.

Pol)*Al Laminate &oisture Barrier (Aluminium tape, coated with polythene on

both sides is applied longitudinally over the cable core with a specified overlap. The

taoe is seased and bonded to the inner surface of the polythene sheath.

S$eat$in%( The screened cable core is sheathed with black polythene compound.

Screenin% an" protection( The cable core with inners sheath is surrounded by a

reasonably close fitted screen of Aluminium in the form of wiresDstripsDweldedaluminium tubing. The aluminium screen is wrapped with a single layer of woven tape

inpregnated with Barium chromate with a specified overlap.

2.+ PA S)stems

A public address system *'A system is an electronic sound amplificationand distribution

system with a microphone, amplifierand loudspeakers, used to allow a person to address

a large public, for e$ample for announcements of movements at large and noisy air and

rail terminals.

The term is also used for systems which may additionally have ami$ing console, and

amplifiers and loudspeakers suitable for music as well as speech, used to reinforce a

sound source, such as recorded music or a person giving a speech or distributing the

sound throughout a venue or building.

Simple 'A systems are often used in small venues such as school auditoriums, churches,

and small bars. 'A systems with many speakers are widely used to make announcements

in public, institutional and commercial buildings and locations. Intercomsystems,

installed in many buildings, have microphones in many rooms allowing the occupants to

respond to announcements.

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Role o, PA S)stem in -uman li,e sa,et)

The 'A system is capable of automatically managing an evacuation procedure by

providing instructions to occupants on what to do and where to go depending on their

location. By doing so, it will ensure the optimi"ation of all fire escapesF capacity andavoid congestion or crowding of fire escapes. In order to provide these, the fire alarm

panel is integrated to the system. This integration enables the system to determine which

floors or area is having an emergency and automatically conducts the evacuation process.

2. Telep$one /c$an%e

The I% *Indian %ailway e$change network is a hierarchical architecture with 7 levels.

ighest level @ Gonal ead 5uarters *G5 and %ailway Board *%B

-edium level @ /ivisional 5 */50owest level @ Important activity centers

All telephones shall be push button type. The signalling may be decadic or /T-

type. The telephones shall be of the following type :@ 3rdinary

@ Secretary and $ecutive type

@ /igital@ -agneto

@ 9 wire

The e$changes shall be interconnected using manual trunks through Trunk 3peratorsor through Subscriber Trunk /ialing *ST/ channels.

All e$change shall be available on I% ST/ network sub&ected to availability ofchannels. ach e$change shall have a distinct ST/ code. Alternate routing shall be

provided as far as possible.

0arious components o, t$e e/c$an%e s)stem

a $change hardware

b $change software

c -an -achine Interaction Terminal '! with 'rinterd Test and measuring instruments

e 'ower supply Arrangement consisting of Batteries, !harger, !hangeover panel and

stand@by system .f Intermediate /istribution rame

g -ain /istribution rame

h 'rotection arrangement

i Attendant consoles& !able *underground and switch board

k Subscriber telephone set

l -aintenance tools

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m /ocumentationn 0ightning protection and arthing arrangement

The man machine language must be in nglish and user friendly. A (/C, keyboard

and a printer alongwith a '! must be available for interaction with the $change.The e$change shall be worked with batteries on float. The capacity of the batteries

shall be to provide minimum < hours back up. 3ne set of battery, two chargers and a

change over panel are to be provided for supplying power supply to e$change. Thecapacity of power supply arrangement shall be 78H higher than the e$change load.

The charger shall be preferably S-'S *Switch -ode 'ower Supply type.

Interme"iate istribution Frame(

The I/ *Intermediate /istribution rame shall have disconnecting type connectors

with facility for isolating e$change indoor and outdoor side. The cable terminals shallbe installed on a rack. 'rotection arrangement shall be available on I/. All testing

for line side shall be done from I/. The I/ may be accommodated in e$change

e?uipment room.

&ain istribution Frame(

All outdoor cable shall be terminated on a rack forming the -ain /istribution rame*-/. This shall provide connectivity between outdoor cable and indoor switch

board cable. The -ain /istribution rame shall be installed in a separate room but not

in the e$change room. An earth is connected across the frame for its entire length andpreferably this shall be a copper strip clamped to the frame..

The outdoor cables shall be &elly filled underground type. The indoor cables shall be

switch board cables. The outdoor cables shall be 18 pair, ;8 pair and 288 paircapacity. The indoor cable shall be ; pair, 28 pair, 18 pair and ;8 pair. The outdoor cable

shall have outdoor Termination Bo$D0ocation Bo$ with terminalsfor proper termination of the cable. The indoor cable shall be terminated on !T bo$esof appropriate si"e. The cables, cable Terminals in !T Bo$es shall be planned with

78H spare capacity. All outdoor cable sheath shall be earthed while entering the

e$change at -/.

Li%$tnin% protection an" art$in% arran%ement(

The earthing arrangement shall be consisting of@ arth pits minimum four with arth electrodes connected in a ring

@ Two earth wires connecting arth lectrodes to arth /istribution rame

@ arth wires from each e?uipment to arth /istribution rame*$change rack, I/, -/, !harger, Battery, en set, 'ower panel, !ables

lectrical Suppl) (

178 ( A! single phase shall be available. #ith power lines suitable for taking the

load, Alternate supply shall be provided either traction supply or / set. The power

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supply shall enter the room through -!B and changeover switch with proper earthingarrangement.

2. &obile Communication-obile Train %adio communication is a digital wireless network based on S-@%

*lobal System for -obile !ommunication@%ailway designed on I% *uropean

Integrated %ailway %adio nhanced etwork unctional re?uirement specification

*%S and System %e?uirement specification * S%S

Basic features of GSM-R are

'oint to 'oint call Allows user to make a distinct call.

(oice Broad cast call Allows groups of user to receive common(oice roup call Allows groups of user to make calls within

mergency call Allows user to call controller by short code or

unctional addressing Allows a user or an application to be reached by

means of a number, which identifies the relevant

function and not the physical terminal.

0ocation dependent addressing 'rovides the routing of mobile originated calls to

the correct controller.

The system consists of following sub systems :

2. -obile Station *-S1.Base Station Sub system *B SS

7.etwork and switching sub system *SS 3perating sub system *3SS

9./ispatcher;.!ab %adio

4.'ower Supply Arrangement

The %adio link uses both /-A *re?uency /ivision -ultiple Access and T/-A

*Time /ivision multiple Access . The 688 -" fre?uency bands for down link and uplink signal are 67;@648 -" and


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Uplink

( MS To BTS)

nlink

"#.! $%& "52.! $%&"#!.# $%& "53.# $%&"#!.2 $%& "53.2 $%&"#!.4 $%& "53.4 $%&"#!.! $%& "53.! $%&"#".# $%& "54.2 $%&"#".2 $%& "54.2 $%&

International &obile Subscriber I"entit) 3I&SI45 It is used to identify the called

-S. It is not known to the user and is used by network only. I-SI is stored in SI-, the

0% and the serving (0%. The I-SI consists of three parts : A three digit -obile

country !ode *-!!, a two digit -obile etwork !ode *-! and a -obile Station

Identification umber *-SI.

The directory number dialed to reach a mobile subscriber is called the mobile

subscriber IS/ *-SIS/ which is defined by the umbering 'lan. This number

includes a country code and a national destination code which identifies the

subscribers operator. It is stored in the 0%.

&obile Subscriber ISN number (

&SISN is a number uni?uely identifying a subscription in a S-or aC-TSmobile

network. Simply put, it is the telephone number to the SI- cardin a mobileDcellular

phone. This abbreviation has several interpretations, the most common one being E-obile

Subscriber Integrated Services /igital etwork@umberE.

The -SIS/ together with I-SIare two important numbers used for identifying a

mobile subscriber. The latter identifies theSI-, i.e. the card inserted in to the mobile

phone, while the former is used for routing calls to the subscriber. I-SIis often used as a

key in the0%*Esubscriber databaseE and -SIS/ is the number normally dialed to

connect a call to the mobile phone. A SI-is uni?uely associated to an I-SI, while the

-SIS/ can change in time *e.g. due to number portability, i.e. different -SIS/s can

be associated to the SI-.

&obile Sub s)stem 3&S4 (

The -S consists of two parts

Subscriber Identity -odule *SI-

-obile ?uipment *-

The SI- is removable and can be moved from one terminal to another. It isauthenticated via a personal Identity umber *'I between four to eight digit. This 'I

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can be deactivated or changed by the user. If 'I is entered incorrectly in threeconsecutive attempts, the phone is locked for all but emergency calls, until a 'I

unblocking key *'C) is entered.

The SI- contains subscriber information and International -obile Subscriber Identity*I-SI.

Po#er Suppl) (

The -obile handset is e?uipped with power supply arrangement *0i@ion battery. It is a

maintenance free battery having detachable independent charger to recharge the battery

after discharge. !harging indication on - screen shows the status of charging.

The -obile handset can be dynamically registered and deregistered in the network for

different functional numbers as per re?uirement of the subscriber *- by keying from

the key pad in a programmed manner and monitoring the action in the display unit of -.

Base Station Sub s)stem 3BSS4 (

The BSS connects the -S and the SS. The BSS contains of three parts.

Base transceiver Station *BTS.Base Station !ontroller

Trans !oder Cnit.

Base Transrecei6er Station 3BTS4 (

The BTS performs channel codingDdecryption. It contains transmitter and receivers,

antennas, the interface to the '!- facility and signaling e?uipment specific to the radiointerface in order to contact the -s. It processes the signaling and speech re?uired for

-es in air interface at one side *via antenna and with BS! in Abis interface *through

'!- 1-bDs in 3! network at the other side.The general architecture of the Base stationis based on the following modules:

The !ompact Base !ommon unction *!B! performs all common functions suchas concentration, transmission, supervision and synchroni"ation. A !B! can bedimensioned according to traffic.

The 'ower Amplifiers *'A amplify the % signal delivered to antenna through the TJ

combiner. ach 'A is physically independent unit, characteri"ed by its fre?uency

band, output power can be controlled independently. The /river receiver units */%J amplify the % signals *two, for diversity, process

the T/-A frames and drive the power amplifier. ach /%J is associated with one %channel, connected to the re?uency opping bus * bus in order to allow base

band hopping and packed as a physically independent unit. 3ne T%J is then made

up of one 'A and one /%J. /epending on fre?uency band , a specific /%J is

available to support / *e@/%J. The Transmission !ombiners *TJ combiners combine the % signals delivered by

several power Amplifiers and duple$ them with the received signals. A variety of

coupling modules can be selected, depending on the type of combining *duple$er,hybrid, the fre?uency band and the configuration *number of T%Js and antennas.

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The reception multicouplers * 0As K %J Lsplitters pre@amplify and split thereceived signal towards the /%J receivers. A variety of %J@splitters can be selected,

depending on the fre?uency band. The Alarm module *%!A00 collects internal and e$ternal alarms. The number of

e$ternal alarms is up to


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Base Station Controller 3BSC4 (

In the BSS network, the BS! performs the tasks related to the BSS e?uipment

management N supervision and to the S- call processing, mainly:

BTS supervision

%adio channel allocation

%adio channel -onitoring

Traffic management

T!C management 3-!@% link management

andover procedures

3peration and maintenance re?uest from the 3-!@% processing

BSS configuration data and software storage

BSS performance counters management

ailure detection and processing

Trans co"er unit 3TCU4(The T!C carries out speech encodingD decoding and rate adoption in data

transmission. It is designed to reduce the number of '!- links needed to convey radio

speech N /ata channels between BTS,BS! N -S!. It enables code conversion of 24

)bps channel from the BS! into 49 )bps channels for -S! in both directions

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Functional O6er6ie# (

It performs the following main tasks related to communication switching and

transcoding:

Switching: the T!C manages a time Ldivision multiple$er connecting the BS!

and -S!.

'!- link management: Csing the configuration data provided by the BS!,

the T!C configures and monitors the '!- links on the A and Ater interfaces.

Transcoding and rate adaptation: !odingDdecoding of the speech frames

and rate adaptation of data frames.

T!C e?uipment management: 3AN- functions: initiali"ation , startup, clock

synchroni"ation from A@interface links, supervision , fault management,software and configuration management.

Net#or7 an" S#itc$in% Subs)stem 3NSS4(

The SS supports the switching functions, subscriber profiles and mobility

management. The basis switching function in the SS is performed by the -S!. This

interface follows a signaling protocol used in the telephone network. The -S! also

communicates with other network elements e$ternal to S- utili"ing the samesignaling protocol. The current location of an -S is usually maintained by the 0%

* ome 0ocation %egister and (0% *(isitor 0ocation %egister. #hen an -S moves

to the ome System to (isited system, its location is registered at the (0% of the

visited system. The (0% then informs the -Ss 0% of its current location. The

authentication center *Au! is used in the Security data management for the

authentication of subscribers.

SS NBSS installed in some sections of Indian %ailways are of -Ds ortel or -Ds

Siemens make.

ata Bases

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ome 0ocation %egister

*0%/ata base for management of mobile subscribers,

stores the I-SI, -obile station IS/ number*-SIS/ and current visitor location register

*(0% address.

)eep track of the services associated with each -S

and 0% may be used by -ultiple -S!s.

(isitor location %egister*(0%

!atches some information from the 0% as

necessary for call control and service providing foreach mobile currently located in the geographical

area controlled by (0% connected to one -S! and is

often integrated into the -S!.

Authentication center *Au! A protected data base which has a copy of the secret

key stored in each subscribers SI- card.This Secret is used for authentication and encryption

over the radio channel. ormally it is locate close to0%.

?uipment Identity * I%%egister

!ontains a list of all valid mobile station e?uipment

within the network, where each mobile station is

identified by its International -obile ?uipment

Identity *I-I

Po#er Consumption (

The average power consumption is 2


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2.8 FOIS

reight 3perations Information System *3IS was implemented in Indian %ailways as an

initiative to leverage the use of Information Technology in the freight segment as an aid todecision making and to ultimately improve the freight services. After successful

completion of trials and its implementation in orthern %ailway, the system comprising

two modules@ %ake -anagement System and Terminal -anagement System@ was rolledout to all the "ones over Indian %ailways. This was introduced, inter alia, to enhance the

accuracy and reliability of operating data to provide a real time view of transactions and

to serve as a decision making tool in allotment of rakes to customers and improved assetturnaround.

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Fig 5: System Architecture of FOIS

The design conforms to the state of the art client server technology

using middleware and a %elational /ata Base -anagement System

*%/B-S. Application servers at the !%IS are networked and linked to

a central database for global level transactions. The central database

acts as the repository of all current and historical data. The application

is interface@ready for web@based services like connectivity to customers

and e@payment gateway interface.

Ob9ecti6es o, computerisation

The ob&ectives of computerisation of freight operations included:

O enhancing the accuracy, reliability and timely availability of basicoperating data pertaining to events in the field locationsP

O providing a wide range of information updated in Qreal timefacilitating operating management for better planning, direction and

control of freight operations and revenue accountingP

O efficient scheduling and ?uick turnaround of rakes to enable effectiveand optimum utili"ation of the assets and resourcesP

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O facilitating acceptance of customers orders, billing and cashaccounting of freight traffic from identified nodal customer centers,

which might not be the handling terminalsP and

O global tracking of consignments in real time and seamless availabilityof pipeline of consignments for timely planning and &ust in time

inventory management.

2.: COIS

Indian %ailways have taken up implementation of !oaching 3perations

Information System *!3IS for a better management of punctuality,

coaching stock management and planning tools relating to time tabling

and rake link optimi"ation and to improve overall efficiency of train

services.

Being developed by !entre for %ailway Information System *!%IS,the 'unctuality -odule seeks to provide terminals for installing in all

control offices at the /ivisions and the Gonal %ailway head?uarters

emergency control. The Gonal %ailways have started the daily train

running data entry for testing and removing the software bugs.

Coac$in% Operations In,ormation S)stem 3COIS4: !aptures events

on !oachesD%akes, enerates %eports for -anagement of !oaching

Stock. /ata input predominantly at StationD!oaching Rard

level. #orking on the system at stationDyard level leads to generation of

re?uired data *and memos for the operator.This works as input for-IS. All stationDyard activities from arrival to departure of rake are

captured:

Rard stock entry

/ispute %esolve

Rard 'osition

%ake formation

-odify consist

-ovement *Rard to yard

%emove fit available coaches

%ake $amination

Search eedbacks

/eparture %eporting

Send eedbacks

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enerate memo

Arrival %eporting

2.; Internet

Fig : OSI reference model

The Internet is a worldwide network of computers and computernetworks that can communicate with each other using theInternet

'rotocol. Any computer on the Internet has a uni?ueI' addressthat canbe used by other computers to route information to it. ence, any

computer on the Internet can send a message to any other computer

using its I' address. These messages carry with them the originatingcomputerFs I' address allowing for two@way communication. The

Internet is thus an e$change of messages between computers.

The Internet works in part because ofprotocolsthat govern how the

computers and routers communicate with each other. The nature ofcomputer network communication lends itself to a layered approach

where individual protocols in the protocol stack run more@or@lessindependently of other protocols. This allows lower@level protocols tobe customi"ed for the network situation while not changing the way

higher@level protocols operate. 'rotocols are often talked about in terms

of their place in the 3SI reference model *pictured on the right, whichemerged in 26


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places no constraints on what physical medium or data link protocol isused. This leads to the adoption of media and protocols that best suit

the local network situation. In practice, most intercontinental

communication will use the Asynchronous Transfer -ode*AT-protocol *or a modern e?uivalent on top of optic fibre. This is because

for most intercontinental communication the Internet shares the same

infrastructure as thepublic switched telephone network.

LAN(/espite the growth of the Internet, the characteristics of local area

networks*E0AsE L computer networks that do not e$tend beyond a

few kilometers in si"e remain distinct. This is because networks on this

scale do not re?uire all the features associated with larger networks andare often more cost@effective and efficient without them. #hen they are

not connected with the Internet, they also have the advantages of

privacy and security. owever, purposefully lacking a direct connectionto the Internet will not provide 288H protection of the 0A from

hackers, military forces, or economic powers. These threats e$ist if

there are any methods for connecting remotely to the 0A.


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2.= PRS

%eserved travel by Indian %ailways is facilitated by the 'assenger %eservation System

*'%S. '%S provides reservation services to nearly 2.; to 1.1 million passengers a day onover 1;88 trains running throughout the country. The Indian %ailways *I% carries about

;.; lakh passengers in reserved accommodation every day. The computerised 'assenger

%eservation System *'%S facilitates booking and cancelling of tickets from any of the

9888 terminals *i.e '%S booking windows all over the country. These tickets can be

booked or cancelled for &ourneys commencing in any part of India and ending in any other

part, with travel times as long as =1 hours and distances up to several thousand kilometers.

The '%S Application !3!%T *!ountry@wide etwork of !omputeri"ed nhanced

%eservation and Ticketing is the worlds largest online reservationapplication, developed

and maintained by !%IS. The system currently operates from ; /ata centers. The server

clusters are connected together by a core network that enables universal terminals across

country, through which the travelling public can reserve a berth on any train, between any

pair of station for any date and class.

Fig !: "O#"$%& #et'or( &opology

The main modules of the '%S are the %eservation module, the !ancellation and

-odification -odule, the !harting -odule, the Accounting -odule, and the /atabase

-odule. The passengers re?uest for reservation, cancellation and modification of &ourney

are handled by the system through re?uisition slips. -a&or outputs generated by the system

are %eservationcum@&ourney tickets, !ancellationD-odification tickets, %eservation !hartsand /aily Terminal !ash Summary. The system is also capable of generating different

types of -anagement Information System %eports. The system was audited at ten "onal

railways namely astern %ailway, orthern %ailway, Southern %ailway, !entral %ailway

*!%, #estern %ailway , South !entral %ailway, orth astern %ailway, South astern

%ailway *S%, orth ast rontier %ailway *% and ast !entral %ailway *!%.

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2.1> Control s)stem

Fig): "ontrol *anel %oom

The !ontrol 3rgani"ation of I% has primary responsibility for scheduling and running all trains,and maintaining information on the positions and movements of all rolling stock. *These

functions are collectively known as control@ an area of the railway network is said to beFcontrolledF when a control office is in charge of it.A control chart is drawn up by the sectioncontroller or his staff for each day. The chart plots distance along one a$is *subdivided by block

sections, and showing stations, level crossings, etc, and time along the other.The trains path are

plotted on the chart to show the progress they are makingP the slopes of the paths indicate thespeeds. !olours are used to mark out different categories of trainsP eg: red for mail and e$press

trains, blue for ordinary passenger trains, and black for good trains. !rack or link goods trains

are indicated by special colours. If a train is stabled at a station, a hori"ontal red line is used todenote that. ormally, at the end of a run on a section, the guard for a passenger train hands in

his report of timings and reasons for detentions along the way, so that they can be reconciled

with the control chart. ach division or district has a control office. In some divisions, this

control office is in charge of all trains in the division or district. In other cases, in addition to thehead?uarters control office there may be one or more outstation control offices which control

specific areas within the division. ach line is divided into a number of control sections for

convenience. Sometimes a line may be divided into more than one control section between yardsto account for very dense traffic, and lines with very light traffic may be combined together into

one control section. ach control section has a Fcontrol boardF which includes the telephony

e?uipment for the control staff to talk to any of the stations, block cabins, yards, loco sheds, inthe control section. A control section normally covers about 2;8@188km of a railway line.

3 Signaling

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Signaling is one of the most important aspects of %ailway communication. In the very early days

of the railways there was no fi$ed signaling to inform the driver of the situation of the line ahead.

Trains were driven on sight. But several unpleasant incidents accentuated the need for an

efficient signaling system. arliest system involved the Time Interval techni?ue. ere time

intervals were imposed between trains mostly around 28mins. But due to the fre?uent breakdown

of trains in those days this techni?ue resulted in rear@end collisions. This gave rise to the fi$ed

signaling system wherein the track was divided into fi$ed sections and each section was

protected by a fi$ed signaling. This system is still being continued although changes have been

brought about in the basic signaling methods. arlier mechanical signals were used but today

block signaling is through electric instruments. In the mid 26th century mechanical interlocking

was used. The purpose was to prevent the route for a train from being set up and its protecting

signal cleared if there

wasalready another conflicting route setup. The most modern development in signalinterlocking

is SSI@ a means of controlling the safety re?uirements at &unctions using electronic circuits which

replaced the relay systems supplied up to that time. In Indian %ailways, first trial installation ofSSI was provided at Srirangam Station in 26


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train protection as well. Automatic train stop systems were tried on some main lines in the

2648Fs but were given up following e$cessive vandalism and pilferage of e?uipment and

maintenance problems.

'oints and interlockings may be worked mechanically *rod or pipe linkages are common, but

earlier, double@wire systems were also used or electrically *motor driven. -any points e$istwhich have to be manually operated at the location of the points after using a key to unlock the

points.

Fig +: *oint ,achines

ollowing British practice, I%Fs signalling is essentially route signalling where the signalsgenerally indicate which route has been set for a train, letting the driver choose the speed as

appropriate for the divergences, curves, etc. 3f course no modern system of signalling is purely

route@based or speed@based, and there are elements of speed signalling in some of I%Fs signalling

as well.

+.2 Interloc7in%

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In railway signalling,an interlocking is an arrangement of signal apparatus that prevents

conflicting movements through an arrangement of tracks such as &unctions or crossings. The

signalling appliances and tracksare sometimes collectively referred to as an interloc(ing plant.

An interlocking is designed so that it is impossible to give clearsignals to trains unless the route

to be used is proved to be safe.

%istory of interloc'ing in India

istorically, before the advent of block instruments, access to sections of railway tracks was

done by the issuance of F0ine !learF certificates by the station@masters of the stations to which the

sections belonged. The I'% and I% were in the forefront of mechani"ing this process by

installing block instruments, semaphore signals, and interlocking. 'aper 0ine !lear tickets are

still used in special circumstances and when communications have been disrupted.The adoptionof cabin interlocking progressed rapidly and by 2621 almost the entire Bombay@/elhi route was

e?uipped with it by the I'%. SykeFs 0ock and Block systems were introduced on the BBN!I

%ly. and others starting in 2628 or so. Around this time track circuits and power signalling

*electric and electro@pneumatic were also introduced for points and signals

These were used at ma&or stations such as Bombay, -adras, and !alcutta. By 2672 more than

=88 stations across India had interlocking. 0ever frames from Tyer N !o., #estinghouse *48@ or

=8@lever frames were not uncommon and others, and all@electric frames from Siemens *e.g., at

-adras gmore and -adras Beach in 267; were in use, as were many locally built lever frames

based on various British designs.

,echanical Interloc(ing

etector

A etectoris a very basic mechanical interlocking device that ensures that a signal can be pulled

off for a route only after the points have been set correctly for it. It also ensures that the tongue

rails for the points are positioned correctly *i.e., not warped to one side or another, for instance

because of being damaged in trail@throughs. The detector consists of a a set of signal slides that

operate perpendicular to the a blade connected to the points which determine the route. The blade

connected to the points has a number of notches, matching the number of signals. ach signal

slide has &ust one notch. The notch on the signal slide fits into the notch of the point blade only

when the points are correctly set for the route of the corresponding signal. #hen the signal slide

is positioned in this way, it frees the signal to be pulled off. Then when the signal is pulled off, it

moves the signal slide such that the points cannot be changed because the notch of the point

blade fouls the signal slide.

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&anuall) operate" interloc7in%

This is a form of mechanical interlocking as well, but relies on the signalman to move about

from one set of points and signals to another carrying with him the keys used to operate them. At

small stations and on less busy branch lines various forms of manually operated mechanical

interlocking are still widespread.

Fig -.: ,anually Operated Interloc(ing System

At points controlling catch sidings in hilly areas, often the interlocking is manual where the

driver has to use a key provided by the stationmaster or signalman of the last station before the

siding @@ the key is inserted into the interlock bo$ which notifies the signal cabin and the points

are then set for the main line and the signal is pulled off, giving the train authority to proceed.

*This system is common in many hilly areas, although busier lines with catch sidings are being

provided withautomatically operating delayed signalswhere the points are controlled by a timer

and are set to the main line only after the train has halted for the prescribed period of time.

3.3 PI and RRI

Panel Interloc7in%*'I is the system used in most medium@si"ed stations on I%. In this, the

points and signals are worked by individual switches that control them.

Route Rela) Interloc7in%*%%I is the system used in large and busy stations that have tohandle high volumes of train movements. In this, an entire route through the station can be

selected and all the associated points and signals along the route can be set at once by a switch

for receiving, holding, blocking, or dispatching trains.

Interlockings effected purely electrically *sometimes referred to as Eall@electricE consist of

comple$ circuitry made up of relaysin an arrangement of relay logicthat ascertain the state or

position of each signal appliance. As appliances are operated, their change of position opens

some circuits that lock out other appliances that would conflict with the new position. Similarly,

other circuits are closed when the appliances they control become safe to operate. ?uipment

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used for railroad signalling tends to be e$pensive because of its speciali"ed nature and fail@

safedesign.

Interlockings operated solely by electrical circuitry may be operated locally or remotely with the

large mechanical levers of previous systems being replaced by buttons, switches or toggles on a

panel or video interface. Such an interlocking may also be designed to operate without a human

operator. These arrangements are termed automatic interlockings, and the approach of a train sets

its own route automatically, provided no conflicting movements are in progress.

%egardless of whether the mechanisms are controlled manually or by electronic circuits, and

whether they are operated mechanically or electrically, all interlocking schemes usually enforce

several or all of the following rules:

o signal can be pulled off unless corresponding points are set correctly.

acing points are locked to the corresponding route when a signal is pulled off.

Signals for conflicting movements cannot be pulled off simultaneously.

'oints for conflicting routes cannot be set simultaneously.

Trailing points are locked to the rear when a signal is pulled off.

/istants, warners, repeaters, etc. cannot be pulled off unless the corresponding stopsignals are pulled off.

ate stop signals cannot be pulled off unless level@crossing gates are blocked to road

traffic.

%%I and 'I e?uipment is from Siemens and British manufacturers. In recent years interlocking

accomplished by modern integrated electronic circuitry instead of electromechanical relay

systems has come into use@ Solid State Interlocking *QSSI. SSI is in place at 29 stations

inIndia.SSI e?uipment is manufactured by %/S3. 128 stations have %%I installations, and 26=8have 'anel Interlocking. 19= stations now have %%I installations and the number of stations with

'anel Interlocking has risen to 1,914.

3.3 EI

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In the more advanced electrical or electronic interlocking schemes, the points and signals are

worked from one integrated mechanism in a signal cabin which features a display of the entire

track layout with indications of sections that are occupied, free, set for reception or dispatch, etc.

The interlocking is accomplished not by mechanical devices but by electrical circuitry @@ relays

and switches in older electrical or electropneumatic systems, and computeri"ed circuits in the

newer electronic systems.

$lectrical Interloc(ing

lectrical e?uipment of some kinds may be used even in the mechanical interlocking systems

described above *e.g., electrical relays that operate slotting. owever, the basic operation there

remains mechanical in nature. In electrical interlocking, the fundamental mechanisms use

electric control e$tensively. lectrical interlocking often goes hand in hand with power signaling,

although there are or were installations with electrical interlocking provided for semaphore

signals.

Rela)s

%elays of various sorts are used to turn on or turn off circuits that control signals, points, slots,

level crossing gates, etc. Trac7 rela)sare used for track circuits. Si%nal rela)scontrol signals.

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Fig -- : Indoor %elay %oom

Trac7 Circuits

Track circuits are electrical circuits that are formed including the running rails. They are set up in

such a way that when a train is on the tracks that are part of the track circuit, the circuit is altered

in some way *usually, by current that normally flows in the track circuit being shunted through

the conductive body of the train, thereby activating a detector which may then be used, e.g., to

set signals at danger for the section.

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Fig -/: &rac( "ircuit

Track circuits help with interlocked operation as they allow signals to be pulled off only if the

section of track they control is safely clear of any vehicles. They also remove the human element

of needing to scrutini"e the track for the presence of trains that may be out of view of the

signalling staff or cabinmen. Track@circuiting is mandatory in sections where visibility is a

problem, shunting operations are routinely carried out on the block section outside station limits

on the main running line, or if special situations e$ist, e.g., if the advanced starter is more than

one full train@length ahead of the most advanced trailing points of the station.

A/le Counters

A$le counters are devices that can count the number of a$les of vehicles passing by them on thetrack. A$le counters are installed at either end of the section of track of interestP when the

number of a$les counted at entrance to the section is the same as the number of a$les counted

e$iting the section, it means the train has passed through the section intact. A$le counters are

used in some cases where track circuits are hard or impossible to operate *e.g., where metal

sleepers are provided, making track circuit operation impossible without re@installing the track,

or where conditions are such that there is too much electrical noise and conductivity problems

that make track circuits unworkable.

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+. Centrali?e" Tra,,ic Control

!entrali"ed traffic control *!T! is a form ofrailway signallingthat consolidates train routing

decisions that were previously carried out by local signal operators or the train crews themselves.

The system consists of a centrali"ed train dispatcherFs office that control. The system consists of

a centrali"ed railroad interlocking and traffic flows in portions of the rail system designated as

!T! territory. 3ne hallmark of !T! is a control panel with a graphical depiction of the railroad.3n this panel the dispatcher can keep track of trainsF locations across the territory that the

dispatcher controls. 0arger railroads may have multiple dispatcherFs offices and even multiple

dispatchers for each operating division. These offices are usually located near the

busiestyardsorstations, and their operational ?ualities can be compared toair traffic towers.

)ey to the concept of !T! is the notion of Traffic !ontrol as it applies to railroads. Trains

moving in opposite directions on the same track cannot pass each other without special

infrastructure such as sidingsandswitchesthat allow one of the trains to move out of the way.

Initially the only two ways for trains to arrange such interactions was to somehow arrange it in

advance or provide a communications link between the authority for train movements *thedispatcher and the trains themselves. These two mechanisms for control would be formali"ed by

railroad companies in a set of procedures calledTrain order operation, which was later partly

automated through use of Automatic Block Signals*ABS. Signals in !T! territory are one of

two types: an absolute signal, which is directly controlled by the train dispatcher and helps

design the limits of a control point, or an intermediate signal, which is automatically controlled

by the conditions of the track in that signalFs block and by the condition of the following signal.

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Train dispatchers cannot directly control intermediate signals and so are almost always e$cluded

from the dispatcherFs control display e$cept as an inert reference.

Summar

%ailways transport is an important and ine$pensive mode for travel in India.

In order to meet Indian %ailways demands for e$treme reliability, many developments in the

area of signal and telecommunication has been done in order to provide the most technically@effective solution.

-odern signalling systems using solid state interlocking au$iliary warning systems for

enhancing and ensuring safety, heavier rails, concrete sleepers, elastic fastenings, long spanbridges in pre@stressed concrete, improvements in overhead electric traction, use of information

technology in all area of railway working etc. are the other areas where Indian railways are

utilising modern technology to meet the combined needs of traffic and safety. Still, there is a

great scope ahead for further improvements in the arena for efficient communications in therailways on which engineers are pondering over for a better future in the Indian %ailways.

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training report on telecommunication and signal-indian railways

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